ITEMS FROM RUSSIA

AGRICULTURAL RESEARCH INSTITUTE FOR SOUTH-EAST REGIONS - ARISER

410020 Toulaykov str., 7, Saratov, Russia.

New durum wheat cultivar Valentina.

Nikolai S. Vassiltchouk.

Valentina (D-2034), derived from the cross 'Saratovskaya 59 / Leucurum 1897 // Leucurum 1973 / Saratovskaya zolotistaya' is an early (41 days from emergence to heading), mid-high cultivar with good yield and grain quality. The kernel weight and kernel size are significantly higher than those of all check cultivars. The average 1,000-kernel weight is 45.5 g, compared to 39.7 g for Krasnokoutka 6 and 40.8 g for Ludmila. Valentina provides a high and good quality semolina yield.

The gluten strength of Valentina is higher than that of Krasnokoutka 6 and Saratovskaya zolotistaya and equal to that of Ludmila. The SDS-sedimentation test averages 54 ml. The yellow-pigment content is higher than that of Saratovskaya 59 and Ludmila, but less than that of Saratovskaya zolotistaya. Protein content nearly equal to that for all of the mentioned checks. Falling number is 421 sec, higher on average than those of all check cultivars. The high grain quality of Valentina gives pasta products good cooking quality.

Valentina has improved resistance to local population of loose smut, and it is rather tolerant to BYDV. This new cultivar is highly adapted to severe dry conditions that are quite typical for the south-east regions of Russia. Valentina was released in 1998.

The influence of combined stresses on morphogenesis of wheat tissue culture in vitro.

A.Yu. Kozlova, S.V. Tuchin, and V.V. Kireeva.

The combined stresses of high temperature and desiccation on morphogenesis in wheat callus cultures and the expression of heat resistance in wheat somaclones were studied. Somaclones of the spring bread wheat cultivar Prokhorovka were developed. The callus cultures were initiated from immature embryos using Linsmaer and Skoog`s (LS) medium. After 30 days, embryogenic calli were transferred to fresh LS medium. Desiccation of the callus cultures was induced by a low water chemical potential (WCP) in the medium. Three WCP-depression levels (- 9 J/mol, - 18 J/mol, and - 36 J/mol) and three temperature levels (25, 30, and 35 C) were used (see Table 1). After 50 days, all variants of calli were put on fresh LS medium for plantlet regeneration.

An increase of selective pressure was found to induce an increase in callus necrosis and rhizogenesis and to decrease plant regeneration. Nonlethal inhibition of plant regeneration was experienced when wheat calli were incubated on media with different levels of WCP at 25 C. Raising the cultivation temperature to 35 C led to a higher sensitivity in plant regeneration to WCP depression. The combined stress did not influence rhizogenesis of wheat callus cultures at 25 and 30 C. The regenerants from heat-resistant calli (adapted calli) developed, and their sexual progenies were obtained. The somaclones (R3-R4) were screened for their reaction to heat stress by heating seeds at 54 C for 30 min. The original cultivar Prokhorovka was susceptible to heat stress, and the somaclones differed in their heat stress reactions. Low reaction and susceptible types occurred. The frequency of resistant types was about 37 % among unadapted somaclones and about 60 % among those adapted to a - 18 J/mol WCP depression level.

The molecular characteristics of adaptivity of wheat callus cultures.

Yu.V. Italianskaya and S.V. Tuchin.

Previous investigations revealed specific changes in the stress proteins (heat shock proteins, hsps; and the peroxidase and esterase isozymes) of bread wheat somaclones resistant to low and high temperatures and osmotic stress as compared to their parental forms. In the present study, the protein systems in the callus cultures of two bread wheat hybrids N 2 and N 11, selected from local cultivar crosses were analyzed. N 2 is a drought-resistant form, and N 11 was created for growing under intensive agriculturel conditions and is not resistant to drought. Callus cultures were initiated from immature embryos on Linsmaer and Skoog medium. Embryogenic calli were transferred to fresh medium with selective osmotic agent (polyethylenglycol (PEG) 6000). Thirty days later, the PAGE patterns of esterases and hsps were analyzed after heat stress (42 C, 90 min). The protein profiles of the N 2 calli differed from those of N 11, even in medium without PEG agent. N 2 was remarkable for increased activity of the Est-1 isozyme, and for large numbers of LMW-hsps. Calli subculture in a medium with PEG revealed that N 2 adapts to osmotic stress. This adaptation was manifested most under heat stress conditions, which led to a considerable increase in the synthesis of LMW-hsps, and new Est-1 and Est-3 isozymes. However, selected calli of N 11 were found to have markedly decreased esterase activity and sharply supressed synthesis of HMW-hsps. The adaptivity of N 2 to osmotic and heat stresses in callus culture indicates that genetic material was transferred from the drought-resistant parent into the hybrids.

Somaclones of wheat with tolerance to Helminthosporium sativum.

N.V. Anikeeva and M.L. Vedeneeva.

Helminthosporium sativum is one of major pathogens of wheat in southeast Russia. Liquid cultures of this fungus contain toxic substances that inhibit the growth of wheat roots and calli and can be used for selection of resistant somaclones. The toxin concentration in filtered liquid medium is correlated with inhibition of the elongation of wheat roots. We used culture filtrate toxins (CTF) for selecting wheat somaclones with resistance to races of H. sativum spread in southeast Russia. The somaclones were developed from the spring bread wheat cultivar Saratovskaya 58 (S 58). Callus cultures were initiated from immature embryos on Murashige-Skoog (MS) medium. Embryogenic calli were transferred to fresh MS medium containing various CTF concentrations. Then, we used some direct and step selection techniques. Plantlets were regenerated from all variants after 30 days.

Nonlethal inhibition of plant regeneration was obtained after 1 month of incubation of wheat calli in a medium containing up to 50 % CTF (unadapted calli). Growth of wheat calli and regeneration of plants were inhibited when the cultures were sprayed twice with undiluted CTF. Plants were regenerated from toxin-resistant calli (adapted calli), and their sexual progenies were obtained. The original cultivar S 58 is susceptible to H. sativum in field experiments, and somaclones derived from toxin-adapted calli have tolerance to the fungus. The somaclones had higher yields in comparision to S 58 in test plots. Morphologically, the tolerant somaclones were higher tillering, and their height and number spikes/head compared with those of S 58. Thus, the somaclones developed from toxin -adapted calli are more tolerant to H. sativum and may serve as a source of resistance to this pathogen for wheat breeding programs.

Tissue culture methods for wheat breeding programs in ARISER.

T.I. Djatchouk, S.V. Stoljarova, N.N. Nosova, O.N. Nosova, and N.F. Safronova.

For breeding bread wheat resistant to biotic and abiotic stresses, different in vitro methods for improving grain yield and grain quality are used at the ARISER. Different interspecific and intergeneric crosses were developed using embryo culture and microclonal propagation. The genetic material of tetraploid species T. durum, T. dicoccon, T. persicum, and T. timopheevi was transferred to bread wheat. Transfer of genetic material from T. monococcum to bread wheat is known to be difficult because of problems in crossing these species. We used four different approaches to incorporate genes for leaf rust, stem rust, and powdery mildew to bread wheat: a) doubling of chromosomes T. monococcum and producing autopolyploids (AAAA); b) using bridging crosses with tetraploid durum wheat; c) doubling the chromosome number of 'T. durum / T. monococcum' hybrids creating AAAABB amphiploids; and d) directly crossing T. aestivum and T. monococcum.

To date, we have created hybrids between T. durum and T. monococcum and hybrids between three species 'T. durum/T. monococcum//T. aestivum'. A hexaploid triticale from the local winter durum wheat Jantar Povolzhja and local varieties of rye was developed.

The nutrional and breeding requirements for southeast Russia now are being investigated. The response of interspecific hybrids of bread wheat with different tetraploids in anther culture was studied. Among the tetraploid species studied, T. persicum (accession VIR 13385) was the most responsive one. The androgenesis parameters (number of embryoids per 100 anthers and green plant regeneration) were the same or higher when compared not only to tetraploid species, but to hexaploid wheat. Interspecific hybrids of bread wheat with this species also had a high value for these parameters. In backcross derivatives, the androgenesis was nearly that of the reccurent parent. Over 300 DH lines from the interspecific hybridization of bread wheat with tetraploid species were developed. Most of these are hybrids of T. aestivum and T. persicum. Only some lines from crosses of the bread wheat with T. durum, T. dicoccon, and T. timopheevii were created using anther culture.


The influence of Rht genes on wheat anther culture.

O.V. Tkachenko, T.I. Djatchouk, and Yu.V. Lobachev.

In different reports on wheat anther culture, androgenesis parameters were shown to depend on both genetic and environmental factors and also 'genotype x environment' interactions. Little information is available about the androgenesis genes themselves and their relationships with other genetical systems. We studied the androgenesis potential in wheat anther culture using the Rht genetic system. In the first experiment, we used crosses betwen Rht1, Rht2, and Rht3 in the Saratovskaja 29 and Novosibirskaja 67 bread wheat backgrounds. In the second experiment, Rht1, Rht3, and Rht14 were used in a Saratovskaja 29 background, and Rht1 and Rht14 in the background of durum wheat Charkovskaja 46. The data show the relationships between androgenetic responsiveness of the bread wheat and Rht genes. The dominant gene Rht3 increased all androgenetic parameters in both backgrounds, but statistically confirmed results were obtained only in the background of Novosibirskaja 67. The same tendency was observed in the Saratovskaja 29 background, but was not confirmed statistically. The Rht1 gene decreases the main androgenetic parameters in both backgrounds studied. Further experiments are necessary to prove the relationships of Rht genes with bread and durum wheat potentials for androgenesis.

Winter wheat breeding on adaptation in ARISER

A.I. Pryanishnikov, E.N. Maslovskaya, L.N. Romanova, and T.W. Kulagina.

The middle and lower Povolghia of Russia are regions unfavorable for winter wheat production. Hard winter frosts and hard summer droughts are the main environmental factors that influence winter wheat yield. Therefore, the breeding of production cultivars is possible only on the basis of high adaptivity to these stresses.

In the first stages of the winter wheat breeding program at ARISER, this problem was solved by using individual selection from land race populations. The standard, highly adaptable cultivars Lytescens 329 and Lytescenc 1060/10 were created in this way (work by Dr. G.K. Meister G.K.).

During the second period of breeding, hybridization followed by selection from wheat­rye hybrids created cultivars with a high level of winter hardiness and drought resistance. These cultivars include Lytescens 230 and Lytescens 434/154 (work by Dr. N.G. Meister).

The production of new, highly adapted cultivars then was based on intravariental hybridization. A local cultivar often is used as one parent of the cross. Saratovskaya 8 and Saratovskaya 90 (work by Dr. W.P. Laskin) have been most successful in this work at ARISER.

Selection of the parental forms for crosses then was based on the differences in the adaptive properties of cultivars. The study of these differences is based on the quantitative value of winter wheat response in actual external conditions.

We have bred cultivars that differ in their level of adaptive properties, such as winter hardiness. The type of adaptation is due to differences in cultivar reaction to the main vectors of external influence (dose, duration, and periodicity).

Nine types of winter wheat adaptation were found in Saratov winter conditions. The most common types were revealed. The main cultivars Saratovskaya 90, Saratovskaya 8, and Mironovskaya 808 accounted for more than 80 % of these types among all cultivars studied. We now cross cultivars with contrasting types of adaptations, in order to create transgressive forms for winter hardiness.

Laboratory of Genetics and Cytology ­ ARISER, 7 Tulaikov st., Saratov, 410020, Russia.

A study of races and the pathotype composition of local wheat leaf rust.

V.B. Lebedev, Yu.E. Sibikeeva, D.A. Yusupov, and L.M. Kudimova.

During the last few years, local leaf rust populations have changed significantly. This fact explained by frequent epidemics of leaf rust during the period of 1990­98, and the spread of new cultivars with monogenic resistance (for example L503 and L505 with Lr19).

During 1993­96, leaf rust pathotypes carrying between 9 and 30 genes of virulence were identified in the Saratov district with differing frequency. The virulence genes p2b, p2c, p3, p14a, p14b, p17, and p18 were observed during all years. Virulence genes p1, p2a, and 011 were ovserved at high frequency (61­68 %) in the local populations. Virulence genes p10, p15, and p20 were detected with a frequency between 50­57 %; and genes p3a, p3ka, p16, p21, p22a, p22b, p23, p32, p34 + T3, and p10 + 23 between 26­47 %. A much lower frequency (11 %) was observed for genes p28, p26, p25, p27 + 31, p24, and pTt. The virulence genes p9 and pTr were not found in the local leaf rust populations.

Leaf rust populations detected resistant bread wheat lines with the genes Lr9, Lr24, Lr34 + Lr13, M5, and M6.

The local leaf rust population between 1993 and 1996 consisted of the following races: 15, 21, 25, 57, 77, 122, and 143. Race 77 was the dominant population, and race 15 discovered for the first time. In 1997, race 77 again was the dominant race; but 1, 103, 57, 167, 121, 122, 129, and 140 also were detected.

An additional set of bread wheat cultivars in addition to the traditional set were used for detection of leaf rust races. This additional set included Prohorovka (Lr23 and Lr3), L 503 (Lr19), and Kavkaz (Lr3 and Lr26). Virulent pathotypes to the Lr23/Lr3 combination were observed with frequencies of 47.1 %, 56.9 % to Lr19, and to the Lr3/Lr26 combination 27.5 %. Pathotypes virulent on both Lr19 and the Lr3/Lr26 combination were found in 17.6 % of the cases.

The pathogenicity of the leaf rust population on bread wheat in 1997.

S.N. Sibikeev and S.A. Voronina.

The growing season for bread wheat in 1997 was warm and wet. Leaf rust populations developed to moderately epidemic rates in these conditions. Infection types were noted on cultivars and lines of bread wheat with different Lr genes and combinations of genes. Of lines with Lr19, LrAgi1, LrAgi2, and LrAgi3 (Sibikeev et al. 1996), 23 had ITs = 3. A mixed IT ranging from 0;1­3 was observed for lines with Lr25 and Lr26. In the field, gene combinations Lr19 + Lr6, Lr19 + Lr25, Lr19 + Lr16, Lr19 + Lr23, Lr25 + Lr23, Lr27 + Lr32, and Lr16 + Lr3 were highly resistant with an IT = 0.

Leaf rust inoculum was collected in the middle of August and reinoculated in the greenhouse on NILs of Thatcher with different Lr genes, KS86WGRC02 (Lr39), KS89WGRC07 (Lr40), KS90WGRC10 (Lr41), KS91WGRC11 (Lr42), KS92WGRC16 (Lr43), and TA5543 (Lr45) for determining the pathogenicity of the population. The following avirulence/virulence formula was obtained: 9, 16, 21, 23, 24, 25, 26, 27, 28, 39, 40, 41, 42, 44, 45 / 1, 2a, 2b, 2c, 3a, 3ka, 3, 10, 11, 13, 14a, 14b, 17, 18, 19, 20, 22a, 30, 32, 33, 34, Agi1, Agi2, Agi3.

Variation was observed for the following effective Lr genes: IT = 0;1 (Lr9, Lr23, Lr41, and Lr42), IT= 1­2 (Lr25 and Lr26), IT = 2­2+ (Lr21, Lr27, and Lr44), and IT = 2+­3­ (Lr16, Lr28, Lr39, and Lr40). Some discrepancies occurred in the data for Lr23. The Thatcher NIL with Lr23 showed an IT of 0;1, but the cultivar Erschovskaya 32 with Lr23 had an IT of 3. However, the cause of the variation has been the combination of Lr22b and Lr23 in the Thatcher NIL.

The use of T. durum and T. dicoccon genomes to improve the bread-making quality of bread wheats.

S.N. Sibikeev, S.A. Voronina, and V.A. Krupnov.

The wide hybridization program in the Laboratory of Genetics and Cytology at ARISER is introgressing genes for resistance to leaf rust, powdery mildew, loose smut, and some virus diseases from T. dicoccum and species of Agropyron and Aegilops. The wheat­alien lines combine resistance to disease, drought, and heat resistance and will help increase the crop potential of bread wheat. These lines also provide high protein content and glutenin quality. For example, cultivars L 503 and L 504 have leaf rust-resistance genes from Ag. elongatum. Agropyron elongatum also has been used successfully for improving bread-making quality.

A set of F12 backcross lines from L 503 and L 504 were hybridized with the durum wheat cultivars M 69, M 26, S 57, and K 10 and hexaploid plants were produced. These lines are promising wheats with excellent bread making quality. In the drought conditions of 1995­96, the yield of this group was equal to that of L 503 and significantly higher than those of cultivars S 29 and S 58. These lines had high glutenin content and alveograph dough strengths between 354­428. The dough strength of L 503 in these conditions was 217. Similar postitive effects for grain yield and bread-making quality also were obtained from hybrids with T. dicoccum and also for A. elongatum and A. intermedium with wheat.

Production of wheat­rye translocation lines.

S.N. Sibikeev, Yu.E. Sibikeeva, and A.I. Pryanishnikov.

A set of spring wheat-rye introgression lines was produced while attempting to transfer genes from rye into wheat. The pedigree of these lines is 'L 503 / S 5 // L503 F12'. L 503 is a spring bread wheat, and S 5 is a rye cultivar. Two lines, N 2057 and N 2837, were produced from this material. N 2057 has high leaf rust resistance from rye. F1 crosses made, and meiotic analyses are shown in Table 1.

The data for the Lr gene that is present in the translocation lines are different than data for Lr26 and Lr25. Segregation data from the F2 of the above crosses showed that the leaf rust resistance is monogenic and different from Lr25, but identical to Lr26. This conclusion was confirmed by scoring the Sec1 gliadin locus in L 2075. The Sec1 locus is linked tightly to Lr26. However, the possibility still exists that the Lr gene in L 2075 may not be on chromosome 1B.

Line 2837 has a T5RL·5AL translocation chromosome. The cultivar L 503 is awnless, but L2837 is bearded. Heading data indicate that 5RL substitutes for 5AL with the B1 inhibitor, but not Vrn1. The Hp gene was used as a marker for the 5RL arm. The presence of the translocation enabled this line to overwinter during 1996-97. The average cellular concentration of the sap of this line is higher than that of the winter wheat Donskaya besostaya but lower than that of Mironovskaya 808.

Agronomic traits of durum wheat cultivars and lines in the epidemic leaf rust and powdery mildew conditions of 1997.

V.A. Elesin.

High precipitation during June, 1997, induced epidemics of leaf rust and powdery mildew in field yield trials. The agronomic traits of durum wheat cultivars and lines differing for ear and leaf color were evaluated. The number of spikes/m2 were similar for the cultivars Saratovskaya zolotistaya, Ludmila, Melanopus 69, Bezenchukskaya 139, and the lines differing for ear and leaf color. Low levels of rust infection (4­13 %) were observed on most of these lines, except Saratovskaya zolotistaya and Ludmila, which had 40 and 57 % infections, respectively. The severities of powdery mildew were 8.7 % on Bezenchukskaya 182 and 12.5 % for Melanopus 69. The other cultivars and lines had between 30 and 40 % infection. Higher yields were obtained for Bezenchukskaya 182 (3.1 T/ha) and lines with light-green, waxy leaves (3.0 T/ha).

The study of cultivars and lines resistant to loose smut of bread wheat.

A.E. Druzhin, V.A. Krupnov, and S.A. Voronina.

Eleven cultivars and lines of spring bread wheat were studied for resistance to loose smut under field conditions in the 4-year period from 1994-97. The wheats were ranked into three groups according to the severity of loose smut infection. The first group included those cultivars and lines with 0-0.4 % infection. The lines L 2040, L 503, L 505, L 1089, L 164, and L 400 and the cultivars Saratovskaya 29, 55, and 58 belong to this first group. Lutescens 62, with 0.5 % infection belonged to the second group, and the third group included L 528 with greater than 0.5 % infection.

These cultivars and lines also were grouped according to heading date. The first group was early flowering and included Lutescens 62 and L 164 and L 2040. The second group flowered 3­4 days later and included S 55, S 58, L503, and L505. The last group, which flowered 4­5 days later than the early-flowering lines, included the lines L 528, L 1089, and L 400.

The line L 2040 (pedigree: L 503 / S 57 // L 503) continues to be more resistant to leaf rust than L 164 (pedigree: L 504 / S 57 // L 504; disease severity 0.06 %) after 4 years of testing. The lines differ from each other only with respect to the NIL used in the cross.

Reaction of cultivars and lines of spring bread wheat to the Saratov population of P. recondita f. sp. tritici in 1997.

O.V. Zubkova and V.A. Krupnov.

An epidemic of leaf rust on spring bread wheat began during heading but did not damage grain yield. The severities of leaf rust on wheat cultivars and lines are given in Table 2. The most resistant line in 1996­97 was L 400, with Lr23 plus an unknown gene. Althought the lines and cultivars with Lr19 were susceptible to leaf rust, the severity of the disease was significantly less than on cultivars without resistance genes. Line L 62, which does not have a specific Lr gene, was slow rusting during the epidemic. The NIL L 400S was more resistant than L 359; however, we have no indication which Lr gene is responsible for the increased resistance.

Laboratory of Plant Physiology ­ ARISER, 7 Tulaikov st., Saratov, 410020, Russia.

Phenotypical variability in mesophyll structure of the wheat flag leaf.

Luda O. Mozayskaya.

Effects of different temperature and water conditions on the structure of flag leaf mesophyll cells of several cultivars of T. aestivum were studied for 3 years. The variance in the number of chloroplasts in the mesophyll cells was insignifiant (see Table 1). The most variable characteristic is the number of mesophyll cells in the flag leaf area. The years 1987 and 1988 were droughty. However, in 1988, although all wheat cultivars contained a high number of mesophyll cells per leaf area, the cells were small. Different conditions during flag leaf development in this year probably caused this difference. In a drought year, the chlorophyll content of the leaf area usually is the same as in a rainy year but may be higher, possibly because of a high nitrogen content in flag leaves. Thus, the flag leaf in drought conditions develops photosynthetic apparatus with xeromorphic characteristics with a large number of chloroplasts per leaf area. The volume of the mesophyll cells and the mean temperature of the air during the period of flag leaf development are highly correlated.

The role and degree of apical dominance in different wheat species.

Olga A. Yevdokimova.

To estimate apical dominance, we removed the main shoot of wheat plants during booting (after growth of the leaf blade of the fifth metamer). The production of tillers after main shoot removal was noted.

After removal of the main shoot, any increase in the number of productive tillers on one plant was observed compared to the control. The number of productive tillers increased by 2.5 in common wheat and 3 in durum wheat. In emmer wheat, characterized by high tillering in the control, tiller number increased a little more than 10 %. The reduction in the number of productive tillers of the total plant was insignificant in all three wheat species (Table 2).

Changes in the plant productivity after removal of the main shoot are given in Table 3. The general yield of tillers of common wheat was 185 % that of the control, and grain yield was 200 %. In durum wheat, the general yield increased 300 and the grain yield 500 %. However, increasing the tiller yield did not compansate for loss of yield from the removal of the main shoot. Generally, grain yield on the whole plant was reduced between 35-55 % (Table 3).

The different wheat species responded differently to removal of the main shoot. Plants of common and durum wheat increased productive tillering and their morphology was unchanged compared to the control. In addition, yield components of the tillers increased greatly, indicating a high level of apical dominance of common and durum wheat. Plants of emmer wheat increased productive tillering only in 1.1 %, and the plant structure was changed in comparison to the other species where tiller growth was doubled. Removal of the main shoot in emmer wheat does not depress tiller growth.

The influence of fertilizers and irrigation on nitrogen concentration in plants.

K.N. Sher and V.A. Kumakov.

A direct association between doses of nitrogen fertilizer and a plant's nitrogen concentration (NC) is a well-known fact. However, when there are high humidity differences, the correlation is less clear. Thus, to predict the correct effective fertilizer application, it is necessary to account for differences in these complex factors. In our laboratory, two different fertilizer applications, N60 P60 K40 and N120 P120 K80, with and without irrigation, were studied in the droughty conditions of the Volga Region during a 2-year period. Changes in biomass and NC were evaluated in relative values. The study was made on two spring bread wheat cultivars, Saratovskaya 29 and Opal, which differ from each other in their drought tolerance. Comparisons for each year indicate a slightly positive influence of irrigation on NC. Under the highest application of nitrogen fertilizer, a relative increase of NC in irrigated compared to nonirrigated conditions was observed in both years. The plant NC remained unchanged in nonirrigated trials during both years. Compared to the unirrigated trial, however, NC even decreased after the application of fertilizers in irrigated trials. This fact indicates that nitrogen under these conditions may be a regulated trait of the plant. The nitrogen fertilizer together with irrigation stimulates growth and creates the best microclimate at planting and, consequently contributes more toward growth of the nonnitrogen-containing part of biomass. Thus, the influence of fertilizers on NC in plants is uncertain, and depending on available moisture capacity, a plant's NC can increase, decrease, or remain constant. However, the influence of irrigation on NC is always possitive.

The structural organization of the leaf photosynthetic apparatus of T. aestivum cultivars is linked with drought resistance.

Alexander I. Pozdeev.

Drought resistance in plants is determined by several internal factors. The ability to form an optimum photosynthetic apparatus structure changes in different conditions.

In drought conditions, wheat develops a leaf apparatus with xeromorphic characters, reduced leaf blade area, and decreased volume of mesophyll cells and size of air pore, but increased numbers per unit of leaf area. The effect is condensed vascular elements. The structural organization of such leaves permits a significant increase in transpiration per unit of leaf area to rescue the plants from burnout. The water expenditure of these plants is not increased by the reduction of leaf area. These adaptations contribute to the photosynthetic function of leaves under conditions of inadequate water and high temperature.

We studied the structure of the photosynthetic apparatus in leaves of different segments in order to determine the causes of productivity decrease under drought conditions. Drought resistant and susceptible cultivars of spring bread wheats similar in morphology and ontogeny were used.

During a drought year, each subsequent segments formed in a more xeromorphic character than the preceeding one. Therefore, the structural differences between the resistant and susceptible cultivars increased as the number of the segments increased (Table 4). Under droughty conditions, the variation between cultivars in the organization of the leaf photosynthetic apparatus showed that the volume of cells in the susceptible cultivars changed less than than the in resistant one, and the general number of mesophyll cells of the leaf blade was reduced. This trait of susceptible cultivars can be a cause for an increase in the diffusion of carbon dioxide into the mesophyll and have a negative effect on the photosynthetic activity of the leaves. In the drought-resistant cultivar, cell volume in drought conditions is the most important factor, but the general number of mesophyll cells remains the same. In calculating the unit of leaf blade area, the content of these cells essentially increases with a decrease in volume. Thus, drought-resistant cultivars are characterized by a higher xeromorphic structure of the leaf photosynthetic apparatus.

Secondary sources of nutrients for grain filling in spring bread wheat.

A.P. Igoshin.

In regions where weather conditions are inconsistant, photosynthesis and supply of plant mineral minerals (mainly nitrogen) from the soils between florescense and when the grain is waxy ripe do not always satisfy the requirements of growing and grain filling. The accumulation of nutrients in the vegetative organs is of great importance in these conditions.

A method to separate the dynamics of structural and storage matters in vegetative organs (first in the straw) was produced in our laboratory. This method accesses the accumulation of carbohydrate assimilates and their distribution in the internodes. The greatest quantity of storage carbohydrates accumulated in the middle (second internode from the top) part of stem and (under optimal conditions) in the lower part of stem where its quantity may reach 50 % of its structural mass.

Storage carbohydrates are present as fructans and mobile mono- and disaccharides. The role of mobile sugars in the general storage of carbohydrates ranges from 15-50 %. During the waxy-ripe flowering period, carbohydrate concentration is higher in the middle part of stem regardless of weather conditions. The high gradient of mobile-sugar concentration between the source and the growing grains and root system remains constant. After florescence, the concentration of mobile sugars in the middle part of stem and the average diurnal speed of growth (mg/d) of the grains have a highly possitive correlation, with the maximum approximately at the end of the linear growth of the grains.

The accumulation of stem carbohydrates is complete in grain filling under any weather conditions, except extremely optimal conditions. The structural carbohydrates depend on the conditions before and after florescence. In other words, worse conditions after florescense (drought, lodging, and damage by pathogens) compared to conditions during vegetative growth affect grain yield. This dependence is represented by the regression equation: y = - 14.4 + 19.3x, where x = the ratio of the biomass increment of the vegetative organs (leaves plus straw) of the main stem from shoot to florescence to waxy-ripe grains, and y = the contribution from the reutilization of structural matter in grain filling, %.

Under a special combination of conditions, the process of grain filling even includes cellulose (up to 10 % of the initial mass). The vegetative organs always use nitrogen in high levels (up to 60-80 %). The earliest and greatest nitrogen use during grain formation happens in years with optimal conditions until florescence and then deterioration of weather conditions. These conditions result in the reutilization of ash elements (up to 26-29 %).

The reutilization of structural matter from vegetative organs only partly compensates for the negative influence of unfavorable enviromental conditions on growth and grain filling. In these conditions, the destruction of some grains are destroyed.

Some aspects of growth in vegetative segments of the main shoot of spring wheat.

Nataly A. Zakcharchenko.

During 1993-95, field experiments were designed to study the effects of external factors on the morphogenesis of vegetative segments and their parts (leaf blade, sheath, and internode) of the main shoot of bread spring wheat plants. Thirty plants were dissected daily to determine the space-time relation between appearance and completion of growth of the next segment and its associated parts, and the growth of the next segment, which was still inside the sheath tube. These dissections determined the relationship between 'visible' (without dissection) and 'hidden' growth.

The division of segment growth into hidden and visible is conditional, because all of the growing wheat stem is in the tube formed by sheath, the total growth of the segments possibly can be considered hidden. In this case, hidden growth of a segment is that growth before its appearence from the sheath of the previous segment. Visible growth is logically determined as including growth from the moment of appearance of the top of a segment from the underlying segment. The growth of any part of the segment is the sum of the underlying parts in the previous segment. So growth is considerably more them the gain of the organ after its appearance from sheath tube. Thus, the true gain from the appearance from the tube to completion of leaf blade growth of the middle segments (IV-V) is 70 %, and leaves of layers VI-VIII is 23-48 %.

Reverse regularity is observed for sheath and internode. Another part of growth is the emergence of the blade from the underlying segment. For example, the length of a leaf from the moment of appearance is 58 mm, and the sheath is 8 mm. At the end of growth, the length of the leaf blade on an intact plant is 143 mm, where 85 mm is gain in the leaf blade from appearance to the end of growth, and 58 mm during emergence from underlying segments. At the end of growth, the sheath gain is 27 mm from regulation (106 mm), and 79 mm from the appearance at the top of the sheath of the tube to the end of growth of the sheath.

In drought conditions, hidden growth increases are most typical for the higher segments. During the drought of 1995, growth of the sheath and internode were almost absent, and the ears hardly pushed out from the sheath of last leaf. The control of growth of separate shoot segments and their parts (excluding high segments internode) in the field on intact plants is nearly impossible.

PRYMORSKEY UNIVERSITY OF AGRICULTURE
K. Marx str. 105A, kv. 167, 680009 Khabarovsk, Russia.

Ivan Shindin.

Publications.

Shindin I et al. 1977. Results of spring wheat samples study of the world wheat varieties collection of the Russian Research Institute of Plant Growing under the conditions of the Far East. In: Spring Wheat Selection. Kolos Pub House, Moscow. pp. 144-151.

Shindin I et al. 1977. Inheritance of quantity characters in shpring wheat F1 hybrid. Siberian Bull Agric Sci, Novosibirsk 3:22-28.

Shindin I et al. 1977. Results and prospects of spring wheat breeding in the Far East. In: Spring Wheat Selection. Kolos Pub House, Moscow. pp. 93-100.

Shindin I et al. 1977. Inheritance and interrelation of quantity characters in spring wheat hybrids. All-Union Cong Geneticists and Breeders, Lenningrad. Pp. 590-591 (abstract).

Shindin I et al. 1978. Correlation of quantity characters of spring wheat. Trans Far Eastern Res Inst, Khabarovsk. 26:34-45.

Shindin I et al. 1979. Inheritance of efficiency as well as components in spring wheat hybrids under the conditions of the Far East. Siberian Bull Agric Sci, Novosibirsk 3:28-34.

Shindin I et al. 1980. Inheritance of some characters in reciprocal spring barley hybrids under the conditions of the Far East. Vashnil Papers, Moscow. 4:7-10.

Shindin I et al. 1981. The best forms of barley and their use in selection. J Select Seedbreed 3:18-19.

Shindin I et al. 1983. Combination capacity of spring barley varieties under the conditions of the Far East. Siberian Bull Agric Sci, Novosibirsk 4:31-38.

Shindin I et al. 1985. Results and prospects of spring barley selection in the Far East. Trans 'Intensification of plant growing in the Far East' Novosibirsk 48:42-51.

Shindin I et al. 1987. Selection of agricultural plants in the Far East. In: Barley. Khabarovsk Pub House. Pp. 24-45.

Shindin I et al. 1987. Prediction of selective value of barley population on the basis of hybrids of previous generation. Trans 'Selection and agrotechnics of field crops in the Pryamurye'. Novosibirsk pp. 23-29.

Shindin I et al. 1987. Race composition and resistant gene efficiency to nigra loose smut of barley of local population. Trans 'Selection and agrotechnics of field crops in the Pryamurye'. Novosibirsk pp. 39-43.

Shindin I et al. 1989. 'Dalnevostochnaya 10' spring wheat. J Select Seedbreed 6:27.

Shindin I et al. 1989. Inheritance of resistant to nigra loose smut in spring barley hybrids of reciprocal crossing under the conditions of the Far East. Siberian Bull Agric Sci, Novosibirsk 2:23-28.

Shindin I et al. 1990. Particular features of spring barley hybrids analysis having bred by crossing of distichous and multicereal varieties. Siberian Bull Agric Sci, Novosibirsk 2:23-28.

Shindin I et al. 1990. Selection of spring wheat of intensive type in the Far East. Trans 'Selection and seedbreeding of field crops in the Far East'. Novosibirsk pp. 3-10.

Shindin I et al. 1990. Initial material of spring wheat and use in selection of spring wheat varieties of the intensive type. Siberian Bull Agric Sci, Novosibirsk 5:19-24.

Shindin I et al. 1990. Inheritance of some characters from F1 and F2 hybrids of spring and winter wheat. Inter 'Selection, seedbreeding and the technology of breeding agrocrops in the Prymorskey Territory'. Novosibirsk pp. 3 16.

Shindin I et al. 1992. Results of field crops breeding in the Far East. Inter 'Selection of sort agrotechnics of field crops in the Far East'. Novosibirsk pp. 3-10.

Shindin I et al. 1992. Evaluation of spring barley samples on resistance to germination of the kernel in an ear. Inter 'Selection of sort agrotechnics of field crops in the Far East'. Novosibirsk pp. 39-43.

Shindin I et al. 1993. Use of haploproduction technology and haplonds in spring barley breeding in the Pryamurye region. Sci Tech Bull, Novosibirsk. 1-2:3-11.

Shindin I et al. 1993. 'Erophey' spring barley. J Select Seedbreed 3:49-50.

Shindin I et al. 1994. 'Khabarovchanka' spring soft wheat. J Select Seedbreed 2:50-51.

Shindin I et al. 1995. Achievements and problems of cereal crops breeding in the Far East. Inter 'Selection and technology of agrocrops breeding in the Far East'. Khabarovsk pp. 24-30.

Shindin I et al. 1995. Germplasm of spring barley resistant to extreme ecological factors. Inter 'Selection and technology of agrocrops breeding in the Far East'. Khabarovsk pp. 31-39.

Shindin I et al. 1997. 'Rus' spring barley. J Select Seedbreed 1:39.

Shindin I et al. 1997. Achievements and problems of spring wheat selection in the Russian Far East. Ann Wheat Newslet 43:196-197.

Shindin I et al. 1998. Selection of spring wheat in the Far Eastern selective center. In: Selection and Seedbreeding, Kolos Publish House, Moscow. 1-2.

THE RUSSIAN PEOPLES FRIENDSHIP UNIVERSITY
Ul Efremova, I8, kv. 7, Moscow. 119048, Russia.

On light reaction (photoperiodism), wintering, and vernalization in wheat.

A. Fedorov.

Light reaction (photoperiodism) and wintering have long been considered to be two different phenomena determined by different causes. Photoperiodism generally implies the influence of diurnal variation in light and dark periods on the development of plants (Skripchinsky 1975). Wintering implies the capability of winter-type plants to delay the formation of organs or fruit (Vasiliev 1956). The basis of wintering is that plants need a prolonged exposure to low temperatures for vernalization, initiating the change from a vegetative to a generative phase (Lysenko 1952; Razumov 1961). The delay of development, or wintering, is adaptive and leads to the hardening of winter-type plants sown in the autumn.

A similar adaptive delay of development in alternate winter-type plants is related to their reaction to light (photoperiod). Alternate winter-type plants differ markedly in later tillering under short-day conditions (Fedorov 1973, 1983, 1989). Our recent data from studies of the developmental patterns of alternate wheats, perennial grasses, and hybrids from crosses between vernalized, alternate, and winter types have concluded that the photoperiodic responses in long-day unvernalized and winter-type cultivars are basically the same. The ability for wintering, like the photoperiodic response, is based on the reaction of plants to light as seedlings, and the differences between these are mainly quantitative (Fedorov 1983, 1989).

The winter wheats Mironovskaya 808 (most winter and frost hardy), and Besostaya I (lesser degree of winter and frost hardiness); the alternative wheats Czech (high response to photoperiod and medium winter hardiness) and Surkhak 5688 (from central Asia, with low photoperiodic responce and low frost tolerance; and the unvernalized cultivar Saratovskaya 29 (weakly photoperiodic and poor frost tolerance)were studied. The F1 plants from crosses between the different types (spring, winter, and alternative) are distinguished from each other and from the parents by their sensitivity to light during the seedling stage and the response to vernalization (Table 1).

The F1 of 'alternative / spring' and 'winter / spring' crosses develop significantly slower under short-day conditions than the spring-type parent Saratovskaya 29. The F1 hybrids from 'winter / alternative' crosses also lag in their development markedly compared to the hybid plants of the two combinations. Crosses between winter and alternative plants are delayed not only in short days but also in long (normal) summer days. The progeny of the cross 'winter / alternative' have a long tillering phase similar to that of winter wheat, but head at the end of summer.

The date of heading depends on both cultivars used in the cross. When Czech Alternative is crossed with different winter wheats, the duration of vegetative growth as expressed by photoperiodic response is greater as the winter habit of the hybrid became more pronounced. Particularly, the F1 of the cross 'Czech alternative / Lutescens 329 (winter type)' headed later and lagged behind a 'Czech alternative / Besostaya I' hybrid when grown under a short day regime. Thus, the degree of the photoperiodic response is determined by the winter paren. The F1 also lag in development under long-day conditions but not as much as winter cultivars, unlike the alternative cultivars.

These data suggest that plants of different developmental types are distinguished by their photoperiodic response. Delayed development under short days in alternative cultivars, and under both long and short days in winter cutlviars is basically the same process. Both the reaction of unvernalized alternative-type cultivars (lag in development under short days) to photoperiod and the wintering ability of winter wheats (lag in development during long and short days) are adaptive characteristics ensuring development of winter hardiness in the autumn before the cold period.

Similar to the cultivars, first generation hybrids react stronger to vernalization. During long days, the F1s of a vernalized and an alternative and a vernalized and a winter type do not show any difference in development and have no delay in development. 'Winter / alternative' hybrids have a considerably longer delay in development under long days and an accelerated development after vernalized seed were sown. All hybrid combinations respond to vernalization more effectively in short, than in long days, the rate of development under short days being longer. On the whole, reactions to light and vernalization are intermediate between those of the two parent cultivars, but closer to that cultivar with the less degree of winter hardiness.

The F2s of the crosses between cultivars of the different types differ markedly in their segregation (Fedorov 1989). No winter plants result in the F2 from 'spring / alternative' wheat crosses. In 'winter / spring' cross F2 populations, 5-10 % of the progeny are winter type. The greatest number of winter-type plants (up to 50 %) segregate in the F2 of 'winter / alternative' crosses. In the F2 from crosses of the same winter wheat with spring and alternative cultivars, the greater the number of winter-type plants is, the more pronounced the photoperiodic reaction. These results indicate that the winter hardiness of the winter-type cultivars and the photoperiodic reactions in unvernalized alternatives and spring wheats are basically the same; the differences are mainly quantitative.

The winter hardiness of winter cultivars is not based on the duration and conditions of vernalization as thought but on the photoperiod of the plants during the seedling stage. Winter and alternative culitvars differing in development type show amost no difference in duration and pattern of vernalization. Development and length of the vegetative period are determined by the reactions to light during tillering.

There are two photoperiodic reactions in plants: a strongly expressed reaction in unvernalized plants and a weakly expressed reaction in vernalized ones. The former determines the length of the vegetative period in spring sown plants and the type of development; the second determines the same for autumn-sown plants. Vernalization does not determine differences in the length of the vegetative period and development, but rather plant development is determined after vernalization.

References.

Fedorov AK. 1973. Some data on genetics of wheat ontogenesis. Proc 4th Inter Wheat Genet Symp, Columbia, MO.

Fedorov AK. 1988. Plants of alternative character. Alma Ata (In Russian).

Fedorov AK. 1989. Physiological-genetical basis for the type of plant development and length of the vegetation period in wheat. Cereal Res Comm 17:121-127.

Mathon CC and Stroun M. 1960. Lumiere et floraison In: Le Photoperiodisme. Paris, France.

Lysenko TD. 1952. Agrobiologia Selhozgiz (In Russian).

Rasumov VI. 1961. Environment and development of plant. Selhozgiz (In Russian).

Skripchinsky VV. 1975. Photoperiodism, its origin and evolution. Izd Naka (In Russian).

Vasiliev IM. 1956. Wintering of plants. Izd AN SSSR (In Russian).