MARATHWADA AGRICULTURAL UNIVERSITY

Wheat and Maize Research Unit, Parbhani - 431 402, Maharashtra, India.

Dr. Ekbote Award to Dr. K.A. Nayeem.

Dr. K.A. Nayeem, Wheat Specialist since 1974 at MAU Parbhani, was awarded the Dr. Ekbote Award in November, 1996, in Pune. His significant contributions to agricultural botany including genetics, cytogenetics, and plant breeding include standardizing heat tolerance parameters and developing high-temperature tolerant wheat cultivars PBN 51, PBN 142, Ajantha, PBN 1625, and PBN 1607-2. The award, consisting of cash and a citation, was established at the Agarkar Research Institute (Maharashtra Association for Cultivation of Sciences). Dr. Ekbote developed the famous wheat varieties Hybrid 65 and Hybrid 11, which ushered in a similar kind of green revolution in India that Mexican varieties of wheat did in the early seventies. For this landmark achievement, the Jawaharlal Nehru University of Agriculture, Jabalpur, M.P., awarded a Doctorate (Honoris Causa) in 1973. Other cultivars of wheat developed by Dr. Ekbote include H-24, H-38, and H-23, which have proven to be favorites of the farming community for their rust-resistance quality.

Parbhani-51 -- a heat-tolerant wheat for the warmer regions of Maharashtra.

K.A. Nayeem.

Bread wheat is an important crop of India, accounting for nearly 90 % of the total wheat production. The Indo-Gangetic plains area is the bread bowl of India. The area under wheat cultivation was approximately 24 million hectares with a production estimated at 63-65 million tons during 1994-95 growing season. The productivity was 24 q/ha (Nagrajan, The Hindu Survey of Indian Agriculture, 1995). However, the productivity in Maharashtra is low (15.00 Qx/ha) because of several constraints. Apart from the input shortage, a short winter season and the prevalence of high temperature throughout the crop season restrict vegetative growth and put limits on productivity. Hence, breeding for heat-tolerant varieties is essential for breaking the yield barriers in the state. As a result of the research efforts at the Wheat Research Unit at Marathwada Agricultural University, a promising wheat designated Parbhani-51 (PBN-51), a heat-tolerant wheat, was recommended and notified for the warmer regions of the Maharashtra state during January, 1996.

The yield data for Parbhani-51 are presented in Tables 1 and 2. A stability analysis at three locations (under six sowing dates) over 3 years in the All India Wheat Coordinated data, indicated that PBN-51 is a stable variety and is suitable under favorable and unfavorable climatic conditions. Thus, Parbhani-51 has wide adaptability under high as well as low temperature conditions. Parbhani-51 exhibited 20.28 and 9.65 % increases in grain yields over the best checks, HD 2189 and MACs 2496, respectively.

Table 1. Stability analysis of wheats for three locations and 3 years (1990-93), including the All India Wheat Coordinated trials.

The cultivar is a selection from the heat-tolerant nursery raised every year at NBPGR, New Delhi and is derived from the cross `BUC "WP TypographicSymbols">S'/FLKS/VEE 'S'=. Parbhani-51 has dwarf plants and is characterized by profuse tillering, even under high temperatures. Leaves are nonwaxy and dark-green. Grains are amber in color and of medium size. PBN-51 flour is quite suitable for soft-textured chapaties with 14.6 % protein. Sedimentation value is 36 and gluten is 12 % (dry basis). The cultivars MACS 2496, HD 2189, and Sonolika possess 14.3, 15.3, and

14.8 % protein and 11.5. 12.8, and 14.6 gluten %, respectively. The chapati score of Parbhani-51 is 7.9, whereas MACS 2496 scored 6.4, HD 2189 scored 6.6, Sonolika scored 7.4, HD 2380 scored 7.4, and HD 2501 scored 6.4. Hence, this cultivar is superior for chapaties, with regard to texture, aroma, softness, and taste.

Table 2. Summary of farm trials 1992-93 (timely and late sown) average yield in Qx/ha.

The variety has exhibited moderate tolerance to wheat rust, with a ts (trace susceptible) (1.4) in 1990-91 and 10 MR and 1992-93 for black rust and 40 MS (19.4) and 30 MS (10.0) for leaf rusts. The variety has been categorized as heat tolerant on the basis of heat-injury percent (26.04 %). The cultivar has the Lr13 gene, which is widely effective at seedling and adult stages for leaf rust reaction.

In 1995-96, there were high temperatures during winter season, and the maximum temperature did not fall below 30 C, and the minimum temperature remained above 9 C. Humidity readings were 71 % during the morning and 30 % during the afternoon. A normal season generally should have maximum low temperatures of 25-30 C or lower and minimums from -9-5 C on any winter day. The performance of Parbhani-51 during an abnormal season of 1995-96 in three front-line demonstrations were HD-2189 (19.53 Qx/ha), HD-2501 (19.60 Qx/ha), HD-2496 (30.87 Qx/ha), and PBN-51 (38.08 Qx/ha). Because of a profuse tillering habit and tolerance to high temperatures, PBN-51 yielded 38 Qx/ha, whereas MACs 2496 yielded 30.87 Qx/ha.

The variety is recommended for normal and late-sown situations, in which it has yielded 3,700-3,900 kg under normal, and 3,200-3,600 kg, respectively. The variety matures in 120-125 days.

The genetics of nitrate reductase activity in wheat.

K.A. Nayeem and M.V. Veer.

Nitrate reductase is the most important and rate-limiting enzyme in nitrate assimilation in plants. The efficiency of inorganic nitrogen assimilation depends primarily on the activity of this enzyme. According to Shankar (1996), nutritional, environmental, and genetical factors favor high expression of this enzyme. A high level also is often correlated positively to growth and productivity (Shrivastava 1980). Thus, nitrate reductase is of pivotal significance in nitrogen nutrition-linked growth and productivity of plants. During the Rabi 1995-96 season, 45 F₁s and 10 parental lines in two different environments (normal and very late-sown conditions) were planted at Parbhani. Nitrate reductase activity (NRA, "WP MathA"F moles NO₂/g of fresh weight/hr) in leaves of wheat was estimated according to Klepper (1972).

Nitrate reductase activity at 60 days was found to be at its maximum in the parent Kalyansona (5.35) and lowest in PBN-51 (3.47). Among hybrids, the cross `PBN-51 x PBN 1607-2' had the maximum NRA of 6.19 "WP MathA"F moles/NO<sub>2</sub>/g at 60 days followed by `Sonolika x PBN 3235' at 6.07. The cross `HI 977 x PBN 3235' at 60 days was lower at 3.10. Of the 10 parents, PBN 1607-2 had the maximum rates of 4.13 and 3.57 at 90 and 120 days, respectively; whereas PBN-51 was the lowest NRA of 2.72 at 90 and 1.73 at 120 days. The cross `PBN-51 x PBN 1607-2' had the maximum NRA (5.01 and 3.51 at 90 and 120 days, respectively). The hybrid `Kalyansona x PBN 1607-2' had the lowest NRA, 2.51 and 1.62 at 90 and 120 days, respectively.

Table 3. An estimate of the genetic components of nitrate reductase activity in wheat.

The variance due to treatment was found to be significant for NRA at 60, 90, and 120 days (Table 3). Interestingly, NRA in parents and hybrids decreases from 60 days to 120 days. Estimates of the components of variation for NRA indicated that the H₁ and H₂ components were highly significant at 60, 90, and 120 days, but additive component D was not significant at all three stages. The average degree of dominance (H_l/D)^1/2 was more than unity for NRA at 60, 90, and 120 days and in the range of overdominance.

The magnitude of H₁ was larger than H₂, indicating unequal gene frequency and this also was confirmed by the ratio of H₂ to 4H₁, which ranged from 0.22 to 0.24. The proportion of dominant and recessive genes in the parent were more then unity with low h², suggesting that dominance genes played an important for control of NRA at 60, 90, and 120 days.

References.

Klepper V. 1972. Plant Physiol 48:580-590.

Shankar S. 1996. Everymans Sci 31:2:55-57.

Breeding rust resistant lines through recurrent irradiation of land race Sharbati.

K.A. Nayeem.

The landrace Sharbati, highly susceptible to black and brown rusts, was subjected to irradiation during Rabi 1990-91. In the subsequent M₄ generation, only one line of 40 KR was found slightly lower in plant height as compared to Original Sharbati. Pure seed of this irradiation-altered progeny was again irradiated during Rabi 1993-94. To our surprise, only one plant flowered in 34-38 days. This plant was selfed and simultaneously used as a pollen parent on the late variety Parbhani-51 (female parent).

Wide variability was noticed in subsequent generations. Ten lines exhibited R-type field reactions at Mahableshwar during 1994-95 (Table 4). These lines were sent for race analysis to the Wheat Rust Research Station at Mahableshwar (Table 5). Progenies derived from the selfed, recurrent-irradiated plant produced three lines PBN 426, 488, and 489, which were resistant to all pathotypes of black stem rust, and line PBN 489 exhibited resistant to all races of brown rust. The original number of PBN 489 is PBN 3965, which is a semidwarf, profuse-tillering, nonlodging wheat. The race analysis of PBN 3965 was confirmed at the Shimla, Flowerdale rust laboratory during 1995-96.

Variability for subunits of glutenins in induced lines of Sharbati and Parbhani-51 wheats.

S.N. Devkule and K.A. Nayeem.

Several mutants with wide variability were isolated from the Sharbati landrace, which was subjected to recurrent irradiation. Similarly, some early and dwarf lines were isolated in Parbhani-51 after a single irradiation. Some of the derivative lines (eight) from Sharbati and four lines from Parbhani-51 were studied for the variability of HMW-glutenin subunits through SDS-PAGE at BARC, Mumbai.

Table 4. Seedling reaction of some Indian wheat varieties to individual race of black stem rust during 1994-95.

Table 5. Seedling reaction of some Indian wheat varieties to leaf rust.

The electrophorogram of the controls Sharbati and Parbhani-51 and their mutants are in Fig. l. Lanes 4 (PBN 3909) and 8 (3958) have one extra band. The mutants PBN 3904, 3907, and 3909, although possessing similar banding patterns, have position changes, whereas the lines PBN 3955, 395,7 and 3959 resemble the parent Sharbati. The extra bands in PBN 3909 and 3958 may be due to significant disturbance at the molecular level or to additions. Therefore, recurrent irradiation produces not only more mutations, but has a higher ratio of mutations with altered DNA sequences. Although time consuming (6-7 years), the method is cheaper, easier, and comparatively more promising for obtaining new, improved alleles controlling biochemical characteristics in wheat, compared to tissue and cell culture methods.

The four induced lines of Parbhani-51 resemble the parental HMW-glutenin subunits, although morphologically they are different from the parents and among themselves.

Figure 1. Electrophoregram of the control and mutant wheat varieties Sharbati (lanes 1 to 9) and Parbhani-51 (lanes 10 to 14).

Gene action of harvest index, heat tolerance, and quality characters in wheat.

K.A. Nayeem and D.P. Deshpande.

Gene action for grain yield, chlorophyll content, harvest index, and heat injury were studied in a 6-generation model on P₁, P₂, F₁, F₂, BC₁, and BC₂, consisting of three heat-tolerant and three heat-susceptible wheat genotypes (Nayeem and Mahajan 1991) (Table 6). The grain weight per plant was an epistatic interaction, `dominance x dominance' gene action, suggesting a trigenic or higher-order interaction or linked blocks. There was a predominance of additive-type gene action for chlorophyll-stability index. The highest additive-type gene action was noted for harvest index in only one cross `HD 2278 x CC 464', which involved both the susceptible parents. However, heat injury percent was predominantly an additive gene action, indicating homozygous genes that will be useful in isolating or screening desirable types in further generations. The studies suggest that breeding for heat tolerance by crossing one heat-tolerant and one heat-susceptible cultivar may give rise to desirable tolerant types at greater frequency.

Table 6. Estimates of genetic components for heat tolerance and quality characters in wheat.

References.

Nayeem KA and Mahojan AR. 1991. Indian J Genet. 51(3):363-369.

Genetic analysis of some quality and heat-tolerant traits in wheat through Wr Vr graphs.

D.P. Deshpande and K.A. Nayeem.

Studies were made on genetic components on the basis of the method and theory proposed by Jinks (1954). The following results were obtained in a six-generation biometrical model consisting of six parents with the help of Wr Vr graphs (Table 7).

Table 7. Characters, parental distribution of genes, iand nature of inheritance of a six generation biometircal model with six parents.

The above studies revealed overdominance for chlorophyll content. The variety NI 5439 has an equal proportion of dominant and recessive alleles, with a high general mean for chlorophyll content. Hence, the parent NI 5439 will be useful in breeding for high chlorophyll content. Partial dominance was observed for stomatal frequency and heat injury, indicating the presence of additive gene effects. Similar results were obtained from components of variation analysis. Hindi 62 has a dominant gene for stomatal frequency, and Ajantha has an equal proportion of dominant and recessive alleles. The studies suggested that the transfer of dominant genes from Ajantha and Hindi 62 into promising genotypes will produce heat-tolerant derivatives.

Reference.

Jinks JL. 1954. Genetics 39:767-88.

Insert Figures 2 and 3. Original only.

Performance of wheat cultivars in front-line demonstrations in the abnormal season, 1995-96.

K.A. Nayeem, S. Muzaffar, H.P. Bhadarge, and S.T. Shirale.

As compared to 1994-95, 5 C temperatures prevailed during 1995-96, particularly throughout the growing season (Fig 2, p. 135). The relative humidity also was lower, a difference of more than 10 % (Fig 3, p. 135). Cultivars included in a 'Front-Line Demonstration' on farmers' fields were MACs 2496, HD 2189, and PBN-51 under normal planting and HD 2501 and PBN 142 under late-sown conditions (Table 8). The yields of late-sown cultivars ranged from 19.00 to 19.62 Qx/ha. However, when timely sown, MACs 2496 yielded 30.87 Qx/ha and Parbhani-51 38.08 Qx/ha. Farmers preferred Parbhani-51, because of profuse tillering, nonshattering, and better chapati qualities.

The data indicate that in mild winters, Parbhani-51 yields 18.93 % more grain over the best check MACs 2496. Farmers' rallies demonstrating new cultivars were organized at Parbhani, Soyegaon, Urmi, and KVK Jalna.

Table 8. Yield (Qx/ha) of cultivars in six front-line demonstrations (Marathwada), 1995-96.

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