Wheat improvement program, achievements, and wheat breeding strategies in northwestern Himalayas.
Satish C. Sharma, G.S. Sethi, K.S. Thakur, D.L. Sharma, Ashwani Kumar, Shyam Verma, and S.C. Negi.
Wheat is cultivated under diverse agroclimatic situations
(500 m to 2,200 m above sea level) in Himachal Pradesh during
the rabi season in the low to high hill regions and during summer
in the dry, temperate areas. Wheat occupies the largest area of
approximately 370,000 hectares, with a total grain production
of about 600,000 tons. However, the average productivity of wheat
in the state is low (16 q/ha) compared to the national average
productivity level (24 q/ha). This low productivity is attributable
mainly to rainfed cultivation in 83 % of the area; diverse agro-ecological
situations; a high incidence of diseases such as stripe and leaf
rusts, powdery mildew, loose smut, bunt (hill bunt in higher areas
and Karnal bunt in lower hills); 20 % acidic soils; and extremely
cold conditions in the higher hills. Area, production, productivity,
and the specific problems of wheat in different agroclimatic zones
of Himachal Pradesh are presented in Table 4.
Table 4. Area, production, productivity, and specific problems in wheat cultivation in the different
agroclimatic zones of the state of Himachal Pradesh.
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Area (ha) Production Productivity Specific
Zone, climate, and altitude (x 1,000) (x 1,000 t) (q/ha) problems*
______________________________________________________________________________________
I. Submontane, low-hill, 171.5 281.9 16.43 KB, SR, LR,LS, PM
subtropical, 500-650 m
II. Mid-hills, subhumid, 124.4 202.7 16.29 SR, LS, PM,HB
subtropical, 650-8,000 m
III. High hills, temperate, 77.7 100.3 12.90 SR, LS, HB
wet, 1,800-2,200 m
IV. High hills, temperate, 4.5 10.9 24.22 SR, LR, PM
dry, above 2,200 m
______________________________________________________________________________________
Himachal Pradesh 378.1 595.8 15.76
National average ó ó 24.00
______________________________________________________________________________________
*KB = Karnal bunt; SR = stripe rust; LR = leaf rust; LS = loose smut; PM = powdery mildew.
Insert Figure 1 here. Page 109.
National importance. The
hills constitute the focus of infection for stripe rust in the
Indo-Gangetic plains, the `wheat bowl' of the country.
Therefore, the development and cultivation of stripe rust-resistant
cultivars in the hills will protect the wheat crop from this destructive
disease not only in the hills, but also in the plains, by decreasing
the primary inoculum and thereby increasing and stabilizing wheat
production.
Multidisciplinary wheat research efforts were intensified,
The objectives, programs in operation, and achievements to-date
are listed below.
A total of 7,179 exotic wheat genetic stocks and
some land races were evaluated and utilized in wheat breeding
programs between 1985 and 1995. We develop high-yielding wheat
cultivars with multiple resistance to important diseases coupled
with drought tolerance, wide adaptability, and good grain quality.
These cultivars are suitable for the diverse agro-climatic and
production conditions of the state, through `spring x spring'
and `winter x spring' wheat hybridization. A shuttle
breeding program using alternate sites is in operation (through
regional research stations and their satellite stations in different
agroclimatic zones of the state) to develop new cultivars (Fig.
1, p. 109).
The breeding program utilizes two crop cycles per
year during the segregating generations. A summer cycle at Kukumseri
(elev. 2,300 m), a hot-spot of powdery mildew, stripe, and leaf
rust and a winter cycle at Bajaura (elev. 1,098 m), a hot-spot
of stripe rust; Dhaulakuan (elev. 456 m), a hot-spot of leaf rust;
and Palampur/Malan (elev. 1,300 m), a hot-spot of powdery mildew
and leaf rust.
Amount of breeding material (1989-95).
F1, 1200; F2, 1065; F3, 2,140; F4, 2,157; F5, 1,355; F6/F7, 2,012;
and F8, 511 bulks.
Multilocational testing.
The wheat lines developed are evaluated at Palampur, Bajaura,
and Dhaulakuan under rainfed conditions, and based on multilocation
testing, the top-yielding wheat strains with high degrees of resistance
to diseases are included in the Coordinated Trials under different
production conditions. In total, 132 wheat strains were developed/identified
and evaluated in the Coordinated Trials of the Northern Hill Zone
of India.
Alien introduction of desirable genes.
The introduciton of alien genetic material, particularly
for disease resistance, is from rye (S. cereale) into wheat
using a `triticale x wheat' hybridization program.
Achievements. `HPW
42' (Aradhana), a new wheat cultivar, was identified
by the All-India Wheat Workshop (1991) and was released by the
Central Seed Sub-Committee for cultivation in the high altitude
areas of Northern Hill Zone (Himachal Pradesh, J & K and UP
hills) under timely sown, rainfed conditions. The pedigree of
HPW 42 is `VEE `S'/4/PVN `S'/CBB//CNO
`S'/3/JAR/ORZ `S'. The probable gene postulation:
Yr9, Lr26 + Lr1, and Sr31. HPW 42
is a high-yielding, early-maturing wheat cultivar with a high
degree of resistance to stripe and leaf rusts, and flag smut and
with low infestation of the brown wheat mite. HPW 42 has a high
hectoliter weight and amber, hard, medium-bold, lustrous grains
with better chapati-making qualities. The cultivar gives an average
grain yield of 30 q/ha. HPW 42 also has been promising under late
sown, rainfed and irrigated conditions in the low and mid hills
of Himachal Pradesh, giving 32 % and 18 % increases in grain yield
over the cultivars Sonalika and HS 295, respectively.
The newly developed cultivar `HPW 89', pedigree `Intermedio Rodi/HD 2248', has the probable gene combination Yr3, Yr18, Lr23, and Lr34. HPW 89 is high yielding, with a high degree of resistance to stripe and leaf rusts and higher tolerance to Karnal bunt (5.71 %) as compared to the best check cultivar HS240 (11.5 %). This
cultivar is early flowering and has been found promising
under timely sown, rainfed and irrigated conditions of the low
and mid hills of Himachal Pradesh. In `on-farm' trials
in Himachal Pradesh, HPW 89 had a higher grain yield under rainfed
conditions (30.47 q/ha) than the check cultivar HS 240 (25.32
q/ha) (pooled over Zones 1 and 2).
Two cultivars `HPW 114' and `HPW
125' are being evaluated in the advance varietal trial
(AVT) under timely sown conditions, and HPW 119 is being evaluated
in the AVT early sown conditions in the Northern Hill Zone.
Wheat germplasm and promising cultivars are evaluated
for resistance to major diseases each year. The genetics of the
host-parasite interaction of wheat E. graminis tritici
(powdery mildew)-resistance gene postulation and physiological
specialization in loose smut of wheat, were explored.
Achievements. A number
of diverse wheat genotypes with multiple resistance were identified
and are being utilized in wheat breeding programs. Pathogenic
variation was studied in 250 single-colony conidial and ascospore
isolates of E. graminis tritici collected
from different agroclimatic areas. The reaction of the isolates
on powdery mildew resistance genes Pm1 to Pm8 and
gene combinations Pm2 + Pm4b, Pm2 + Pm6,
Pm4b + Pm8, and Pm(Md) revealed the presence
of a large number of pathotypes. Virulence was frequent on genes
Pm3a, Pm4b+ Pm8, and Pm(Md). The components
of slow mildewing resistance were worked out in some commercial
wheat cultivars of Himachal Paradesh. Using specific virulences
of E. graminis tritici gene Pm8, individually
or in combination with other genes, was postulated in Advance
Varietal Trial wheat entries.
We are evaluating the newly developed wheat cultivars
for different sowing dates under rainfed and irrigated conditions,
yield potential, and adaptability through various levels of nitrogen
under rainfed conditions, sensitivity to current herbicides, and
herbicidal control of weeds. We also are developing agrotechnology
for rainfed wheat cultivation in Himachal Pradesh and making front-line
demonstrations of new wheat cultivars and their production technology
at farmers' fields. These demonstrations showed a 25-50
% increase in grain yield over the local cultivars grown in farmers'
fields.
Thrust areas and futuristic programs in wheat breeding.
* Breeding improved bread wheats with higher levels
of drought tolerance and wider adaptability through exploitation
of landraces, agronomic bases, alien species, and `spring
x winter' hybridization programs.
* Studying the effects of vernalization, photoperiod,
and temperature on phenological development and responses of bread
wheats to different intensities of early seedling and postanthesis
drought stresses.
* Introgressing desirable rye traits (biotic and
abiotic stress, resistance, and physiological attributes) into
wheat through recombination breeding.
* Breeding for multiple resistance to important diseases
(yellow and leaf rust, powdery mildew, loose smut, and hill and
Karnal bunt).
* Breaking the present yield barriers through systematic
exploitation of variability and physiological traits.
* Feasibility of developingt hybrid wheat and exploiting
double haploid technology for decreasing the length of the breeding
cycle.
* Genetically upgrading the nutritional and chapati-making
quality of wheat cultivars.