No abstract

No abstract

Aims: To find the relationship between the non-destructive and destructive methods for the evaluation of photosynthetic pigments under field condition concerning heat stress conditions. Study Design:  The crop was sown in factorial randomized block design in three replication. Place and Duration of Study: The experiment was conducted during the (2016-2018) rabi crop season for two years. The crop was sown under timely and late sown condition in the research farm of Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana Methodology: In the present investigation forty-nine advanced breeding lines of Indian mustard were sown under two planting conditions. The data recorded for photosynthetic pigments by calorimetric method by non-destructive methods at three crop stages i.e vegetative, flowering and siliquing.  The relationship between these parameters was carried out by correlation and regression analysis. Results: Regression analysis indicated a non-linear relationship at vegetative stage under both sowing conditions, but at flowering stage, slope of the relationship increased with increasing SPAD and a linear relationship was observed (R2= 0.0362) as compared to vegetative stage. A significant and strong correlation was observed between total chlorophyll (siliquing stage) and SPAD value (flowering stage) in timely sown crop. Positive correlation existed between SPAD value and total chlorophyll at flowering stage and carotenoid content at siliquing stage. Conclusion: The variation in the SPAD value and chlorophyll value is strongly related with the species, distribution of chlorophyll in leaf and hence chloroplast also. The lower value of regression coefficient and insignificant values of correlation might due to non-destructive SPAD values under field condition and sampling for calorimetric estimations.

Elevated temperature is one of the major production constraints of Indian mustard. The present study was aimed to estimate variations in phenology, yield attributes and seed yield under elevated temperature (ET) in temperature gradient tunnels (TGT) and open field for heat tolerance. Fourteen genotypes consisting of introgression lines and the mustard varieties were sown in TGT and open field for two consecutive winter seasons (2017-2019).The phenophases were shortened due to elevated temperature in TGT as compared to control except physiological maturity which was trailed by 17-18 days during both the years. Temperature affect was most severe on siliqua formation and seed filling. Among growth parameters only length of main shoot suffered reduction whereas yield contributing parameters like siliqua on main shoot, siliquae plant-1, seeds siliqua-1 and 1000 seed weight along with biomass, seed yield and  harvest index suffered significant decline in TGT. Average temperature had positive correlation with all phenological parameters except flowering completion, growth parameters except number of primary and secondary branches while yield attributes only with 1000 seed weight, biomass and seed yield under TGT. Interestingly, number of primary branches had significant negative correlation with average temperature under both control (r=-0.59*) and TGT (-0.61*). Phenological traits had strong relationship with seed yield under TGT. However, seed yield had strong relationship with growth parameters, yield attributes under control except for number of primary branches. Biomass had strong relationship with seed yield under both TGT (R2= 0.51) and control (R2= 0.43). Two years testing revealed introgression lines (JA24 and JA53) and varieties (JD6 and Giriraj) tolerant to heat stress.