Goyal, VinodPaidi Raja Sekhar2024-02-172024-02-172023-10https://krishikosh.egranth.ac.in/handle/1/5810206893Indian mustard, also known as Brassica juncea, is a significant oilseed crop that is planted widely in Europe, Africa, North America and Asia. The present investigation was conducted to evaluate the impact of terminal heat stress on morpho-physiological responses and to find a correlation between physiological, yield and yield attributes in 102 Indian mustard genotypes. The crop was sown in the Field Crop Research Area of Oilseeds section, Department of Genetics and Plant Breeding, Chaudhary Charan Singh Haryana Agricultural University, Hisar on 15th October (timely sown) and 16th November (late sown), 2022 with standard package and practice. Observations were recorded at flowering and grain filling stages for phenological, physiological (includes leaf gas exchange traits, NBI, CHI, NDVI, CT and CTD) and biochemical parameters and yield and yield attributes in both timely and late sown conditions. Results revealed that terminal heat stress has a significantly negative impact on photosynthetic rate, NBI, CHI and yield with its attributes as well. Photosynthetic rate, stomatal conductance, NBI, CHI and NDVI show decreased values under terminal heat stress conditions. Yield parameters like primary branches, secondary branches, biological yield, seed yield, the number of siliquae on the main shoot, the number of seeds per siliquae, 1000 seed weight and oil content were reduced under terminal heat stress conditions. Anthocyanin content, flavonoid content and CT were found higher in late sown due to the presence of terminal heat stress conditions. A highly significant positive correlation between seed yield, physiological traits and yield attributes was observed viz., NBI, CHI, CTD and photosynthetic rate while canopy temperature, flavonoids and anthocyanin showed a negative correlation under both conditions. The mean square for blocks was significant for parameters like NBI, CHI, CT, CTD, photosynthetic rate and stomatal conductance under timely sown conditions whereas the mean square for treatments was found significant for NBI, CTD, photosynthetic rate and stomatal conductance under late sown condition. Terminal heat stress at flowering and post-flowering accelerates maturity by shorting the vegetative and reproductive stages, resulting in drastically lower CHI, CTD, photosynthetic rate and NBI and ultimately lowering the yield of the crop. RC-1312, 1205 and 1133 performed better under timely sown conditions while RC-1312, 1099 and 1045 performed better under late sown conditions in terms of NBI, CHI, photosynthetic rate and seed yield and yield attributes.EnglishThesis