Dalvi, D.G.Kardile, Prashant Bhausaheb2022-09-092022-09-092021-12-2122045https://krishikosh.egranth.ac.in/handle/1/5810187546The present investigation on “Assessment of wheat (Triticum aestivum L) genotypes for morpho-physiological & yield contributing traits as influenced by heat stress” was conducted under field condition using 20 genotypes of durum and bread wheat. The experiment was conducted for two years i.e., rabi 2019-20 and rabi 2020-21. Twenty genotypes viz., GW-493, HI-1625, DBW-235, AKAW-4924, PBW-770, MACS-6097, HD-3343, UAS-3002, PBW-822, DWAP-1715, RW-5, MP-1338, DBW-277, RWP-2018, GW-491, HI-1624, HD-2932, DBW-150, WH-730, RAJ-6765 were studied for high temperature tolerance. High temperature stress was induced by manipulation of the sowing dates i.e. normal sowing (control) (25th November, 2019, and 2020), late sowing (high temperature stress) (10th December, 2019 and 2020) and very late sowing (high temperature stress) (25th December, 2019 and 2020) Sowing dates were considered as main plot treatments and wheat genotypes as sub plot in split plot design with three replications. Timely sown wheat i.e. 25th November (3476.82 kg ha-1) gives higher yield than late sown 10th December (3227.24 kg ha-1) and very Late Sown 25th December (3182.24 kg ha-1) condition. The genotype PBW-770 recorded the significantly highest mean grain yield i.e., 4187 kg ha-1, 4068 kg ha-1 & 3926 kg ha-1 under normal, late and very late sown condition respectively. Among the 20 wheat genotypes, the genotype PBW-770 (4097 kg ha-1) followed by GW-493 (3782 kg ha-1), AKAW-4924 (3711 kg ha-1), and MACS-6097 (3566 kg ha-1) were recorded significantly higher grain yield. On the basis of heat susceptibility index and grain yield the genotypes viz., PBW-770, GW- 493, AKAW-4924 and MACS-6097 identified as highly thermo tolerant, are of immense commercial value as for breeding material. Genotype MP-1338 with low mean yield have good academic value in respect of physiological traits can be used for further exploitation in breeding programme. Check Genotypes RAJ-3765 & WH-730 both showed highly thermotolerant behavior with good grain yield, these genetic resources can be useful for improvement of thermo-tolerance in wheat crop. Wheat genotypes under field condition for high temperature stress induced by late sowing, genotypes viz., PBW-770, GW-493, AKAW-4924 and MACS-6097 identified as highly thermotolerant on the basis of their morpho-physiological & biochemical studies. These genotypes showed their higher efficiency to accumulate more dry matter, less reduction in plant height, maintenance of photosynthetically active apparatus, Higher leaf Nitrogen & chlorophyll content, higher chlorophyll stability index, Lower cell membrane thermostability index and higher relative water content. Genotypes PBW-770, GW-493, AKAW-4924 and MACS-6097 identified as suitable for both normal and late sown conditions in Marathwada region of Maharashtra. These genotypes can be used in future wheat improvement programme. These traits may be used in breeding programme for development of thermo tolerant genotypes for late condition under changing climatic scenario. Plant height decreased by 3.65% in late and 4.7% in very late sowing (high temperature stress) at maturity. Decrease in plant height may be due to inhibition cell elongation above 320C. Plant height decreased due to delayed sowing (high temperature stress) in wheat. In present investigation, high temperature stress induced by late and very late sowing caused 5.22% and 11.87% reduction in tillers per meter row length at 90 days. It was observed that total dry matter production plant-1 progressively increased from 45 DAS to 90 DAS and slightly reduced at harvest. Total dry matter production at 60, 90 and at harvest was found to be decreased by 2, 21.4 and 18.6% respectively under high temperature stress of 2.87 0C induced by late sowing compared to normal sowing may be due to decrease in height, leaves and stem dry matter and ear head (at 90 DAS and harvest) at respective days after sowing. Sowing date 10th and 25th December recorded 1.40% and 5.0% reduction in days to flag leaf emergence as compared to sowing date 25th November. It was revealed that genotypic variations were found for days to flag leaf emergence ranging from 29.46 to 39.98 days. Chlorophyll content index of flag leaves at 90 DAS indicated that high temperature stress induced by very late sowing (26.16) and (29.14) in late sown condition caused drastic reduction of CCI in comparison to normal sown condition (35.57) in wheat. The data pertaining to Chlorophyll stability index at 90 DAS indicated, that overall 0.84 % and 1.35 % reduction caused due to high temperature stress induced by late sowing (48.19%) and (47.94%) in very late as compared to normal sowing (48.60%). It was revealed that RWC was drastically reduced by 29.33 % under very late sown condition (37.08%) and late sown condition (37.90%) reduced by 27.76 % in comparison to normal sown condition (52.47%) in wheat. Relative water content ranged in between 36.86 to 47.20 %. In very late sown wheat crop significantly decreased nitrogen content by 6.81% relative to normal sowing (0.88%). The data pertaining to membrane stability index at 90 DAS indicated, that overall, 1% and 2% reduction caused due to high temperature stress induced by late sowing (65.26%) and (64.82) in very late as compared to normal sowing (66.10%). The 9.44% reduction in sugar content caused due to high temperature stress induced by very late sowing in wheat. carotenoid content was drastically decreased to the extent of 34.14% and 23.17% due to high temperature stress induced by very late sowing (0.54 mg g-1 fw) and late sowing condition (0.63 mg g-1 fw) relative to normal sowing (0.82 mg g-1 fw). Days to 100% heading occurred 8.98 and 5.34 days earlier due to vey late sowing by one month (58.29 days) and late sowing by 15 days (61.93 days) in comparison to normal sowing (67.27 days). 100% anthesis completed by 12.22 and 8.73 days earlier due to very late sowing (60.34 days) and late sowing (63.83 days) as compared to normal sowing (72.56 days) in wheat. Days to 100% anthesis were reduced by 16.84% and 12.03% due to high temperature stress induced by very late and late sowing. High temperature stress induced by late and very late sowing caused reduction by 6.22 days (5.84%) and 11.05 (10.38%) in days to maturity as compared to normal sowing. Mean values for grain growth duration were 37.30 days, 34.53 days and 31.82 days under normal, late and very late sown conditions, respectively. High temperature stress induced by late and very late sowing caused 7.69% and 14.69% decline in grain filling duration. High temperature stress induced by late and very late sowing caused 7.22% and 14.67% reduction in number of productive tillers m-2. length of spike decreased by 7.75% and 12.57% under late and very late sown condition and genotypic differences were also found may be due to occurrence of high temperature. Grain weight spike-1 (g) was found significantly maximum under normal sown condition (2.53 g) relative to late and very late sown condition (2.32 g) and (2.19) in wheat. The reduction in grain weight spike-1 to the extent of 8.30% and 13.43% was caused due to high temperature stress induced by late and very late sowing. The high temperature stress induced by late and very late sowing caused 6.92% and 12.93% reduction in 1000 grain weight. The 7.16% and 12.75% reduction in grain yield under late and very late sown condition caused due to high temperature stress of increased temperature occurred at post anthesis stage. . The 10.8% and 22.45% increase in biological yield under normal sowing as compare to late and very late sown condition might be due to longer growth duration of wheat plants under normal sowing provided a little opportunity to accumulate more biomass as compared to late sown plants. Overall, 7.16% and 8.45% reduction were caused in harvest index due to late and very late sowing. Late and very late sowing caused 6.5% and 13.47% reduction in photo thermal efficiency compared to normal sown crop. Significantly higher GDD from sowing to maturity were recorded in 25th November sowing (Normal sowing) i.e. 23630C days compared to10th December sowing (late sowing) i.e. 2250 0C days and 25th December sowing (very late sowing) i.e. 2145 0C days.EnglishThesis