Search

Yield improvement in wheat through grain number and grain weight has become increasingly difficult in many production environments. Can the non-grain yield parameters of yield like height, flowering and maturity be explored as an alternate for further yield enhancement? This study comprehends such possibilities by analysing performance of the released and pre-released varieties evaluated in ten diverse production environments of India during the period 2000-2021. Regression analysis has highlighted relevance of these three crop expressions in wheat yield and based upon their contribution, selection criteria has been suggested for different production environments of India. Magnitude of impact varied under each environment and their collective contribution was highest in a production environment where growth condition was most favourable for wheat growth i.e., north-western plains. Increase in height and maturity duration coupled with early heading was found useful in this region for both wheat category, i.e., timely-sown and late-sown. These three yield determinants were found highly effective in timely-sown of the adjoining north-eastern plains also but under late-sown condition, prolonged heading was the chief yield predictor. Height for timely-sown and maturity for late-sown condition was most crucial for central India. Delayed heading in timely-sown and late flowering with extra height in late-sown wheat had been tipped for yield improvement in peninsular India. Delayed maturity for timely-sown and height for late-sown wheat had been suggested for productivity enhancement in the northern hills. Besides grain yield, this selection strategy based upon height and crop phenology also enhanced grain weight in certain environments. At a time when selection for grain attributes is not providing further push in productivity enhancement; it would be worth trying to explore these non-grain field indicators as selection strategy for further advancement in productivity of bread wheat.

Drought stress is one of the major yield limiting factors in realising the full genetic potential of wheat. In the present study, backcross inbred line population derived from GW322*2/ HI1500 was characterized for different morpho-physiological traits and grain yield under rainfed and irrigated conditions. Principal component analysis revealed that first five components explained over 66.35 per cent of variation. Grain yield showed significant correlation with biomass and physiological traits viz., NDVI2, NDVI3, NDVI5, CT2, CT3 and CT4. The analysis of variance on grain yield data showed that mean squares of environments, genotypes and GEI were highly significant (p 0.01). To determine effects of GEI on grain yield, data were subjected to AMMI and GGE biplot analysis, which identified BILs G20, G2, G254, G214, G44 and G64 as the most stable and high yielding. Based on Smith selection index expected genetic gain for grain yield at 5% was 131.01gm/plot. Hence, selecting genotypes based on morpho-physiological traits will be rewarding under moisture depleting environment.

Fusarium head blight (FHB) is global concern as recent outbreaks reported in Canada, Europe, Asia, Australia and South America. The disease has emerged as one of the most important plant diseases worldwide in 21st century. One of the major threats posed by FHB fungus is the mycotoxin production which is harmful to human and animal health. Development of disease resistant cultivars is the only effective method for managing the disease. Control of these pathogen / Fusarium spp. is also challenging due to limited sources of known resistance. The famous Chinese wheat cultivar Sumai 3 and Frontana are the main sources of resistance to this disease. For genetic analysis and incorporation of FHB resistance into recently released high yielding wheat cultivars, HD 2967 and DPW 621-50, crosses were made with Sumai 3, Frontana and Aldan. The F2 plants from the crosses HD 2967/Frontana (140), HD 2967/Aldan (150), HD 2967/Sumai 3 (169) and DPW 621-50/Sumai 3 (182) were screened for resistance under controlled conditions. Disease score was recorded to identify resistant, moderately resistant and susceptible plants. The genetic ratios for resistance to FHB indicated a complex nature of resistance in all the three donors.

Stripe rust inflicted by the pathogen Puccinia striiformis Westend. f. sp. hordei Eriks can cause marked grain yield reduction and deterioration of the malting quality in barley. Two barley genotypes, DWRB137 (DWR28/DWRUB64) and DWRB143 (DWRB73/DWR83) were identified as resistant (R) for three stripe rust races viz., 57 (0S0), M (1S0) and Q (5S0) at seedling and adult plant stages. These genotypes were crossed with two stripe rust susceptible (S) barley cultivars, RD2035 and Lakhan to study mode of inheritance of stripe rust resistance. All the F1 plants showed resistance against stripe rust race, 57 (0S0) indicating that the resistance (R) is dominant. The F2 generations derived from the crosses namely, Lakhan/DWRB137, Lakhan/DWRB143, RD2035/DWRB137 and RD2035/DWRB143 were tested with inoculum of race, 57 (0S0) under artificially inoculated conditions. The observed frequency of segregants in each F2 generation fit well in a theoretical ratio of 3(R):1(S) (χ 2(T) less than 0.01) indicating that the resistance against the tested race is controlled by a single dominant gene in the genotypes, DWRB137 and DWRB143. To validate the F2 hypothesis, the F3 progenies were also tested under above described conditions and followed discrete segregation of 1 (R): 2 (Segregating): 1(S) ratio in all the four crosses. Test of allelism was also conducted to establish the identity of resistance gene(s) present in the resistant genotypes. The F2 population derived from DWRB137/DWRB143 (R × R) cross fit to 15(R):1(S) ratio showing that the two genotypes had different resistance genes.

Markers linked to QTLs are useful in practical plant breeding, only if they get validated in genotypes of independent populations and diverse genetic backgrounds. 41 SSR markers reported linked to QTLs for grain iron (Fe) and zinc (Zn) concentration in wheat were analysed. Only 16 of them showed polymorphism and the remaining 25 turned out to be monomorphic in 48 wheat genotypes used in the present study. Single marker analysis (SMA) for the 16 polymorphic markers was carried out to assess the linkage between marker and the trait, based on which two markers (Xbarc186 and Xbarc74) for grain Fe concentration and three markers (Xgwm3, Xwms149 and Xgwm538) for grain Zn concentration were validated in the present study. The phenotypic variations explained by Xbarc186, Xbarc74, Xgwm3, Xwms149 and Xgwm538 were 40.2% and 19.8%, 10.7%, 21.7%, and 39.6%, respectively. The validation of these SSRs may be useful in breeding wheat with high grain Fe and Zn concentration.

An experiment was conducted to study the performance of BC2F3 and BC1F4 lines derived in marker assisted backcross breeding (MABB) program for different morphological and physiological traits under late sown conditions. Two QTLs were introgresed into HD2733, one for days to anthesis and other for yield under stress conditions from an identified heat tolerant variety WH730 (donor). The lines were subjected to heat stress by sowing late in the season and the data was recorded on several characters at different phenological stages. A significant difference (P

Stomatal conductance (SC) was evaluated for thirty-six wheat (Triticum aestivum L.) genotypes sown during 201314 and 2014–15 under two dates of sowing. Steady state SC-1 leaf porometer was used to record SC on adaxial leaf surface at late boot (Z 49–50), early milk (Z 73) and late milk (Z 77) growth stages. In late sown conditions, the temperature was high (25.7 to 30.3°C) in boot stage itself and further increased during later stages (32 to 37.4°C). Under these conditions, the genotypes need to maintain an optimum range of stomatal conductance to maintain transpirational cooling without losing too much of water through transpiration. Heat susceptibility index ranged from 0.27 to 1.54 indicating levels of stress tolerance among the genotypes. Heat tolerant genotypes maintained relatively higher SC under heat stress over normal condition. Significant association between high SC with CT and grain yield was observed in all the three growth stages. The study was useful in detailed evaluation of SC and identification of genotypes with stable SC under heat stress. Genotypes KAUZ/AA//KAUZ, BERKUT and RAC 875, maintained high SC over the growth stages. Indian genotypes HD 2932, HD 2987, FLW-18, HW 2004 and RAJ 3765 were equally potential.

The present study was conducted to determine genotypic variations for normalized difference vegetation index (NDVI) at eight different growth stages and its relationship to yield in wheat under terminal heat stress. Thirty six wheat genotypes were evaluated under staggered sowing, timely sowing (15th November, normal), late sowing (15th December, heat stress) and very late sowing (6th January, heat stress) during 2012–13 and 2013–14. The NDVI was recorded at different growth stages viz., flag leaf, booting, heading, anthesis, milk dough, and maturity. The wheat genotypes differed significantly for NDVI at each stage and at each sowing condition. Rate of reduction in NDVI from heading to dough stage was low for genotypes namely, KAUZ/AA//KAUZ, SOKOLL, HW2004, HD2864, HD2967, FLW18, CHIRYA 7 and HD2932. Overall, under heat stress leaf senescence was 7 to 14 per cent faster than normal condition. Genotypes which maintained high NDVI were potential stress tolerant with higher stress tolerance index. Since data recording of NDVI is relatively easier than any other physiological traits, it could serve as indirect selection criteria to measure stress tolerance facilitating selection of the lines from large populations.

In the present study 24 modern cultivars of wheat were subjected to genetic and physiological characterisation in order to ascertain their use as parents in drought and heat tolerance breeding. The physiological traits, canopy temperature and chlorophyll content of flag leaves were found to be widely distributed. Population structure analysis grouped them into seven clusters with optimum k value=7. AMOVA and PCoA (Principal Coordinate Analysis) revealed higher level of polymorphism among the resistant and susceptible groups. The study revealed that the varieties used in breeding program are highly divergent pure breeding lines with unique pattern of alleles.

End-use quality in wheat is complex and is determined by several component quality traits. The traits having high heritability and significant positive correlation with the enduse quality can be utilized for indirect selection for genetic improvement of the end-use quality. Environment wise interrelationship among eight grain quality traits, four farinographic and eight starch pasting parameters along with bread loaf volume were studied in a set of 35 genotypes grown in 10 environments (five locations tested over two years). Genotypes exhibited a wide range of variation within and across environments for the expression of most of the quality traits analyzed for the study. Kernel hardness showed significant positive correlation with flour recovery and water absorption capacity. Grain protein percentage was found to be positively correlated with bread making quality across the environments except for the location where grain filling was affected by boron deficiency in the soil. Path analysis for loaf volume suggested that Grain protein percentage exhibited both direct and indirect effects on loaf volume. Gluten strength (measured as SDS-sedimentation volume) showed an indirect effect on loaf volume through grain protein percentage.

Thirty five genetically diverse bread wheat genotypes were evaluated for terminal heat tolerance in three environments by altering the sowing dates viz., non stress (E1), mild heat stress (E2) and high heat stress (E3) using physiological indices. Twelve genotypes showed the consistent performance under E1 and E3 environments. Genotypic performance varied substantially over the E1 and E3 environments. Genotypes namely, HD 2733, CL 3125, HD 2189, C 306, DBW 14, WR 544, PBW 373, HD 2932, Kundan, HD 2967, HD 2997 and L 512 showed least heat susceptibility index (HSI) for grain yield ranging from 0.1 to 0.5. These genotypes also showed least HSI for other associated characters viz., canopy temperature depression, membrane stability index, 1000 grain weight and biological yield and hence can be regarded as tolerant to terminal heat stress. Since the identified genotypes can cope up the effect of heat stress, they can be utilized for developing heat tolerant genotypes

An investigation was carried out to validate the already known molecular markers Xgwm533, Xcfa2019 & Xcfa2123, Sr24#12 & Sr24#50, Sr26#43 and BE518379, SCSS30.2 and Sr39-I & Sr39-II for stem rust resistance genes Sr2, Sr22, Sr24, Sr26, Sr31 and Sr39, respectively in wheat cultivars Kundan and UP 2338 carrying unknown stem rust resistance gene(s). The Sr2 and Sr22 gene specific SSR markers amplified the gene specific or expected allele in both Sr2 and Sr22 carrying and non-carrying cultivars. Sr24 associated STS markers (Sr24#12 & Sr24#50) amplified their respective expected fragments (500 bp and 200 bp) only in known Sr24 gene carrying cultivar, HD 2851. Two DNA markers (Sr26#43 & BE518379) known for Sr26 gene were screened. Marker, Sr26#43 amplified the specific fragment of 207 bp only in known source carrying Sr26 gene, while other marker, BE518379 functioned as null allele marker by not amplifying the critical band in Sr26 lines. SCAR marker, SCSS30.2 specific to Sr31 gene amplified the gene specific fragment in wheat cultivar UP 2338 confirming the presence of Sr31. Out of 14 entries tested for Sr39 gene including Kundan and UP 2338, the expected PCR product was not amplified in any of the entries indicating absence of Sr39 gene.