Efficacy of calcium chloride and arginine foliar spray in alleviating terminal heat stress in late-sown wheat ( Triticum aestivum L.)

Terminal heat stress leads to sizeable yield loss in late-sown wheat in tropical environments. Several synthetic compounds are known to counteract plant stress emanating from abiotic factors. A field experiment was conducted in Sabour (eastern India) during 2013–2016 to investigate the field efficacy of two synthetic compounds, calcium chloride (CaCl 2 ) and arginine, for improving grain yield of two contrasting wheat cultivars (DBW 14 and K 307) facing terminal heat stress. For this, foliar spray of 18.0 mM CaCl 2 at booting (CC B ) or anthesis (CC A ), 9.0 mM CaCl 2 at both booting and anthesis (CC B+A ), 2.5 mM arginine at booting (ARG B ) or anthesis (ARG A ) and 1.25 mM arginine at both booting and anthesis (ARG B+A ) treatments along with no-spray and water-spray treatments were evaluated in late-sown wheat. The highest grain yield was recorded in treatment CC B+A , followed by CC A and ARG B+A . However, the effect of these compounds was marginal on grain yield when applied only at the booting stage. Grains/ear and thousand-grain weight were found to be the critical determinants for yield in late-sown wheat. During the anthesis to grain filling period, flag-leaf chlorophyll degradation and increase in relative permeability in no-spray treatment were 34–36% and 29–52%, respectively, but these values were reduced considerably in CC B+A treatment followed CC A . Thus, foliar spray of 9.0 mM CaCl 2 both at booting and anthesis stages may be recommended for alleviating the negative impacts of terminal heat stress in late-sown wheat and improving its productivity (>13%).