Study of late season drought stress and planting date on some agronomic traits of advanced winter canola genotypes

Introduction Selection of crops that are adapted to the climate of each region, the selection of suitable and resistant to environmental stresses, and the use of high-yielding farming practices play an important role in increasing the efficiency of rare source of irrigation water. The aim of this study was to evaluate the reaction of rapeseed genotypes to end-stage drought stress in delayed planting conditions. Material and Methods This study was performed to evaluation of late season drought stress on agronomic traits of autumn canola genotypes in two temperature planting dates. Experimental design was done as split plot in RCBD design with 3 replications at two years in Karaj province, Iran. In this experiment, the planting date included timely (7th October) and late planting date (27th October) and irrigation including common irrigation and interruption from slique stage in main plots and five canola genotypes consisted of L1030, L1204, L1110, L1114 and one commercial (Okapi) cultivar. Analyses were performed by using the SAS software version 9 By doing bartlett test and after defining it insignificantly (Except 2 case), combined analysis of variance was done and In order to compare the means, Duncan's multiple range test was used at the 5% level. Studied traits included plant height, branch number, slique number, slique length, seed number/slique, 1000seed weight, biological yield, seed yield, harvest index, oil content and oil yield. Results and discussion Results showed that in both planting dates, interruption of irrigation led to the reduction of yield. All genotypes had higher grain yield with 7th October planting date than late planting date and the effect of interaction between planting date and genotype on all traits except harvest index was significant. The highest mean of traits was obtained on the fifth of October and the genotype L1204. The highest mean grain yield (5118 kg ha-1) was attributed to L1204 genotype in the planting date of October 7 and the lowest mean (2297 kg ha-1) was allocated to L1114 genotype on planting date of 27th October. Highest grain yield were obtained by L1204 at normal irrigation (4733 kg ha-1) and interruption of irrigation (3400 kg ha-1). The highest grain yield in delayed planting condition and stop irrigation after silique stage (2460 kg ha-1) was observed in L1204 genotype. Also, according to results, it was founded that all treatments had significant effects on oil content and the highest oil percentage (44%) was obtained by L1204 genotype. Interaction effect of evaluated genotypes with planting date showed that all genotypes had higher mean at 7th October planting date, and the highest mean oil percentage (44.18%) was observed by L1204 genotypes at 7th October planting date and The lowest mean (41. 39%) was allocated to the Okapi genotype at the late planting condition. The highest mean at 27th October planting date (41.83%) was belonged to L1204 genotype. Conclusion Application of drought stress and late planting date led to reduction of yield in all genotypes but these reductions were less by L1204 genotype in compared to other genotypes.