(Salient Achievements during the past 10 years)
- Wheat varieties developed for different cultivation conditions:
As per the station’smandate, major thrust has been on the improvement of productivity of durum and bread wheats in central India through development of high yielding, heat tolerant, water-use efficient, rust resistant varieties with desired quality traits. Seven wheat varieties including four of bread wheat and three of durum wheat were released during the period 2005-2013. While bread wheat varieties HI 1500 (Amrita) and HI 1531 (Harshita) were released for rainfed / restricted irrigation conditions, HI 1544 (Purna) was released for irrigated, timely sown conditions of Central Zone, and HI 1563 (Pusa Prachi) for irrigated, late sown conditions of North Eastern Plains Zone. Durum wheat variety HI 8627 (Malav Kirti) was released for rainfed / restricted irrigation conditions of Central Zone, and HI 8663 (Poshan) for irrigated timely sown conditions of Peninsular Zone. Recently, durum wheat variety HI 8713 (Pusa Mangal) was released for irrigated timely sown conditions of Central Zone.
- Protocols developed for evaluation of rust resistance in durum and bread wheats:
Appropriate stem and leaf rust pathotypes for evaluating resistance in durum and bread wheats and suitable host genotypes for their rapid multiplication were identified, which can help in developing varieties of the two wheat species with stable and longer lasting resistance to stem and leaf rusts (Ref:Mishra AN et al., 2009. Indian Phytopathology 62:461-468).
- Diverse sources of rust resistance identified in durum and bread wheats:
A number of diverse sources of resistance to stem and leaf rusts have been identified in both durum and bread wheats, based on multi-pathotype tests and genetic studies. Detailed information is given in the following paragraphs:
- Diversity for resistance to stem and leaf rusts in Indian wheat germplasm:
On the basis of seedling responses to 24 pathotypes of stem rust and 40 of leaf rust, at least 18 diverse groups among 71 field resistant durum genotypes, and 17 among 67 field resistant bread wheat lines could be delineated for resistance to stem rust; while at least nine diverse groups among 50 field resistant durum stocks, and 12 among 45 field resistant bread wheat accessions could be identified for leaf rust resistance (Ref: Mishra AN et al., 2011. Indian J Plant Genet Resources 24:283-291).
- Genetic diversity for leaf rust resistance in bread wheat:
Four diverse dominant genes for leaf rust resistance were identified among five bread wheat genotypes viz., HP 1761, HS 365, HUW 468, PBW 498 and VL 832. While the gene in HP 1761 appears to be Lr9, based on parentage and infection type, identity of the other resistance genes is not known. However, these genes appear to be either novel or at least different from the ones common in Indian wheat germplasm (Ref: Mishra AN et al., 2010. Indian Phytopathology 63:406-410).
- Promising source of adult-plant resistance (APR) to leaf rust in bread wheat:
A partially dominant gene for APR to leaf rust in `CPAN 1842’ was found to be different from any of these documented APR-Lr genes viz., Lr12, Lr13, Lr22a, Lr22b, Lr34, Lr35, Lr37, Lr46, Lr48 and Lr49, based on allelic tests.
- Diverse genes for stem rust resistance in durum wheat:
Three diverse genes for seedling resistance to stem rust pathotype 117-6, the one most virulent on durum wheats, were identified among four durum wheat genotypes- AKDW 3347, B 662, GW 1139, and P 6046. (Ref: Mishra AN, et al., 2005. Indian Phytopathology 58:335-338)
- Diverse genes for leaf rust resistance identified in durum wheat:
Seven diverse leaf rust resistance genes, different from Lr23 which is the most commonly postulated one among Indian durum wheat genotypes, were identified among five durum wheat genotypes- AKDW 4339, B 276, CPAN 6118, Guji ‘S’, and VD 2001-14.
- Diverse sources of resistance to stem and leaf rusts in durum wheat:
Diverse genes for resisytance to stem and leaf rusts were identified among five durum wheat genotypes viz., B 662, ED 2398-A, HG 110, IWP 5019, and Line 1172.
- 110 field resistant durum wheat genotypes could be classified in to 22 and 15 diverse groups for resistance to leaf rust and stem rust, respectively, based on their seedling responses to 13 durum-specific pathotypes including eight of leaf rust and five of stem rust.
- Diversity for resistance to stem and leaf rusts in Indian wheat germplasm:
- Phenotypic markers for the rust resistance genes Sr2 and Lr34 validated:
Pseudo- black chaff (`pbc’) and leaf tip necrosis (`ltn’) are being used as phenotypic markers for the widely effective rust resistance genes Sr2 and Lr34, respectively. However, genetic studies ruled out the presence of Sr2 in bread wheat variety Lok 1 despite its `pbc’ phenotype (Ref: Mishra AN et al., 2005. Plant Breeding 124:520-522 ), and of Lr34 in the variety `C 306’ showing `ltn’ (Ref: Mishra AN et al., 2005. Plant Breeding 124:517-519). Similarly, postulation of Lr34 based on `ltn’ in eight other wheat varieties- HI 1077, K 9107, Kalyan Sona, NI 5439, PBW 175, PBW 373, UP 2338, and WH 147 could not be genetically validated.
- Genetic basis of seedling resistance to leaf rust in `Thatcher’ elucidated:
`Thatcher’ is documented to carry the gene Lr22b for adult-plant resistance to leaf rust. Seedling resistance to leaf rust in `Thatcher’ is rare and its genetic basis was not known. Genetic analysis showed that an incompletely dominant gene conditioned seedling resistance in `Thatcher’ to the pathotypes 0R8, 0R8-1, and 0R9. Test of allelism revealed that this gene (temporarily designated LrKr1) was derived from `Kanred’, one of the parents of `Thatcher’. An additional gene (temporarily designated LrMq1) derived from `Marquis’, another parent of `Thatcher’, was effective against pathotype 0R9 alone. These two genes as well as a second gene in `Kanred’ (temporarily designated LrKr2) which was effective against all the three pathotypes, but has not been inherited by `Thatcher’, seem to be novel, undocumented leaf rust resistance genes. (Ref: Mishra AN, et al., 2005. Plant Breeding 124:514-516).
- High b-carotene “dual purpose quality” durum wheat lines developed:
A number of durum wheat lines such as HI 8638, ID 32, ID 319, V 21-12, V 21-13, V 21-16, C 44-3, C 44-29 and C 44-32 have been developed with high b-carotene (precursor of vitamin-A) content ranging from 6 to 9 ppm. These combine high protein and high sedimentation value with “dual purpose quality” suitable for chapati making as well as for pasta preparations. It was found that there was no loss of b-carotene during chapati preparation (Ref: Sai Prasad SV et al., 2005. Indian J Agric Sci 75:165-166).
- Morpho-physiological traits for heat and drought tolerance in wheat:
Biomass, harvest index, stay green nature of flag leaf, canopy temperature depression, root density and root length were useful in identifying heat and drought tolerant wheat genotypes.
- Irrigation scheduling under limited water availability:
Under limited water availability, shifting the customary CRI (crown root initiation crop stage reached 20-25 days after sowing) irrigation to somewhere between 30-45 days after sowing, depending upon the prevailing weather conditions and soil type, improved water use efficiency, resulting in 30-35 q /ha wheat grain yield.
- Alternative tillage options for wheat cultivation in wheat-soybean cropping system under early sown conditions in vertisols of central India:
The `minimum’ tillage (cultivating the field only once with cultivator after soybean harvest) showed non-significant differences for grain and biomass yield, compared to `conventional’ tillage (cultivating twice – with cultivator and then with rotavator) and fetched higher net returns over `conventional’ and `zero’ (no cultivation after soybean harvest) tillage, while benefit:cost (B:C) ratio was at par with `zero’ tillage. Thus, minimum or zero tillage can be adopted to reduce the cultivation cost and facilitate timely seeding of wheat thereby helping in the optimum utilization of available irrigation water.
- Breeder seed of recently released IARI-wheat varieties produced to create diversity in wheat cultivation:
Despite having only six hectares of farm land, the station produced in participatory mode a total of more than 17,000 quintals of breeder seed of recently released IARI wheat varieties during the last ten crop seasons. This led to easy availability of quality seed of improved rust resistant varieties of both durum and bread wheats creating diversity in wheat cultivation, minimizing the chances of recurrence of any rust epidemics.
- Integrated nutrient management in wheat-soybean cropping system:
Half of the recommended fertilizer dose supplemented with 2.5 tons poultry manure/ha gave higher grain yield, net return and return per rupee invested, compared to recommended fertilizer dose. In soybean-wheat cropping system, application of balanced nutrients to wheat crop alone, ensured good harvest of both the crops, without applying any additional fertilizers to soybean crop, and thus reduced the cost of cultivation.
- Application of Zinc and Boron for increasing wheat productivity:
Application of Zinc and Boron significantly increased the wheat grain yields at the levels of 10.0 kg/ha (46.2 q/ha) and 2.0 kg/ha (45.6 q/ha), respectively, over lower levels (44.7 and 44.2 q/ha), and control (41.2 and 42.3 q/ha). Hence, it can be recommended that the wheat crop may be fertilized with Zinc @ 10.0 kg/ha and Boron @ 2.0 kg/ha as soil application at the time of sowing for increasing wheat productivity in central India.
- Yield penalty under extra-early sowing of wheat in central India
Most of the irrigation sources in central India dry out by December-January, and hence, farmers tend to sow wheat extra-early during October first week for the maximum utilization of available irrigation water. However, under these conditions, the reproductive phase is induced early due to prevailing warm temperatures during October-November leading to grain yield reduction. Hence, a study was conducted to assess the extent of yield penalty under extra-early sowing of wheat. Ten wheat varieties including three durums viz., HI 8663, HI 8713 and HI 8627, and seven bread wheats viz., HI 1531, HD 2987, GW 366, MP 3288, Lok 1, GW 273 and HI 1544 were evaluated under extra early-sown (Date of sowing: 5th October) and timely sown (5th November) conditions during rabi 2012-13. In addition to come-up irrigation (given immediately after dry-sowing to facilitate germination), five and three irrigations were provided to extra-early and timely sown plots, respectively. Last irrigation was given on January 10 to simulate the duration of availability of irrigation water in the region. Average grain yield of timely sown plots was 46.9 q/ha, compared to 36.2 q/ha of the extra-early sown ones. Thus, the extra-early sowing of wheat resulted in yield penalty to the tune of 22.8% despite receiving two additional irrigations, compared to the timely-sowing. Yield reduction was considerably higher in varieties recommended for timely sowing (November sowing), compared to varieties recommended for early sowing (October 15-30). Hence, extra-early sowing of wheat in central India just for the sake of utilization of available irrigation water, particularly of the varieties recommended for November sowing, should be avoided.