Late sowing stress tolerance indices for seed yield and contributing traits in rapeseed (Brassica napus L.) genotypes

Abstract

To assess effects of sowing dates on pod number and seed yield in rapeseed (Brassica napus L.), 10 spring rapeseed
genotypes were evaluated in form of randomize complete block design with four replications in normal and late sown
conditions. Significant differences of genotypes were determined for number of pods in normal and late sown (PN and PS,
respectively) and seed yield in normal and late sowing dates (YN and YS, respectively) and their stress tolerance indices
except stress tolerance index and stress susceptibility index of seed yield (Y(STI) and Y(SSI), respectively). Two stress
indices including Y(STI) and Y(SSI) could not separate the genotypes, and all of the genotypes were classified under the
same statistical group but Y(TOL) separated the genotypes in different statistical groups. The genotypes including
Safi7, Safi31 and S841 with low mean value of Y(TOL) were less affected by stress condition under late sown. High mean
value of PN and PS were exhibited for Zabol0 but high mean value of YN (3300 kg ha-1) and YS (1947 kg ha-1) were detected
in Zafar and Zabol0, respectively. The higher value of P(MP), P(GMP) and P(STI) indicate more stress tolerance for pod
number, were shown in Zafar, Zabol0 and Zabol15. Due to high mean value estimate of P(TOL) for Safi47 and Safi31 and
Zabol15, these genotypes were more affected under late sown conditions.