Late-sown stress afflict post-anthesis dry matter and nutrient partitioning and their remobilization in aestivum wheat genotypes

Timely sowing of wheat (Triticum aestivum L.) is a crucial agronomic measure to realize its genetic yield potential, particularly under ever-changing climatic conditions. The present study appraised the genotypic variations of wheat genotypes for dry matter and nutrients' accumulation, partitioning, remobilization and stress indices under timely and late sown conditions of irrigated semi-arid ecology. Five potential wheat genotypes viz. HD-2967, HD-3086, HD-3249, DBW-187 and HD-3226 were evaluated under field conditions, however, the studies for root-system traits were made in PVC tubes. Timely sown wheat had grain yield advantage of 18%, and genotypes DBW-187 (5.77 t ha-1) and HD-2967 (4.78 t ha-1) produced the highest grain yield under the timely and late sown conditions respectively. The days (d) to anthesis and grain filling period under the late sown was hastened by 5.2 d, and shortened by 7.4 d. Timely sowing enhanced the post-anthesis dry matter accumulation and remobilization to the tune of 18.8% and 23% respectively. Nitrogen, phosphorus and potassium accumulated post-anthesis and their remobilization under the timely sown was significantly greater than the late sown, while the contribution of remobilization to grain content was higher under the late sown except for the nitrogen. The canopy temperature was cooler by 2 degrees C under the timely sown, while the canopy temperature depression was greater by 0.8-1.04(degrees)C, at anthesis and dough stages of the crop. The leaf chlorophyll content (SPAD meter value) at anthesis and dough stages improved by 10% and 7.6% due to timely sowing. The genotypes HD-2967 and HD-3249 had relatively greater geometric mean productivity and stress tolerance index coupled with a comparatively higher yield stability index. Further, the root-system traits, that is, total root length (TRL), root biomass and root length density (RLD) were significantly superior both at 50 DAS (days after sowing) and at anthesis under the timely sown compared to the late sown. This study clearly outlined that timely sowing of wheat resulted in higher post-anthesis dry matter accumulation, nutrient acquisition and remobilization along with improved root-system traits and grain yield. Screening of the genotypes, based on stress indices would result in a better understanding of the genotypic performance and improve the genetic yield potential under varying environmental conditions.