Analysis of effects in wheat of high temperature on grain filling attributes estimated from mathematical models of grain filling

Abstract

SU MMARYCompared with growth at 20/15 xC (day/night), exposure of wheat (Triticum aestivum L.) plants to moderately high temperature (30/25 xC) significantly decreased grain weight through shortening the duration of grain filling, combined with small (or no) positive increases in the rate of grain filling. Several mathematical models of grain filling were assessed for their suitability as means of analysing these effects of temperature. The ordinary logistic model was found to be the most appropriate model and was used for the analysis of grain filling responses in four cultivars differing in their responses. Genotypic variation in response to temperature was observed for both rate and duration of grain filling, but the variation for the duration of grain filling among cultivars was small at the higher temperature. Significant correlation was found between single grain weight with the rate, but not with the duration, of grain filling at high temperature, which indicated an important role for synthetic processes involved in grain filling in the temperature sensitivity of wheat cultivars. As they are independent traits, both rate and duration are required selection criteria for the improvement of heat tolerance. Responses of one attribute estimated from the logistic model, the inflection point of the course of grain filling, may give insight into a temperature response that is distinguishable from that associated with the duration of grain filling. The inflection point appears to be worth including as a criterion in selecting for high temperature tolerance in wheat.

Truncation of grain filling in wheat (Triticum aestivum) triggered by brief heat stress during early grain filling: association with senescence responses and reductions in stem reserves

“…In other studies where (milder) heat treatments were applied throughout grain filling, the degree to which grain filling was accelerated by heat showed genetic variation that manifested in differential responses of final SGW (e.g. Sofield et al 1977;Wardlaw and Moncur 1995;Zahedi and Jenner 2003). In our study, there were a few cases where significant growth rate effects manifested after the heat treatment, namely decreases for MGR and SGR in Waagan, and increases for SGR in Millewa and Gladius (Fig.…”

“…MGR (mg day -1 ) and grain filling duration (GFD, in days) were obtained using the following equations, as described by Zahedi and Jenner (2003).…”

Early anthesis and delayed but fast leaf senescence contribute to individual grain dry matter and water accumulation in wheat

“…In fact, grain filling rate is more important than its duration for individual grain weight, and more responsive to the increased assimilate availability through stay-green. This responsiveness has also been seen under the stressed conditions such as heat, drought and elevated CO 2 that lead to faster but shorter grain filling (Li et al, 2001;Yang et al, 2004;Zahedi and Jenner, 2003 (Zhang et al, 2014).…”

“…Data of grain dry weight was then fitted over the accumulated thermal time after anthesis using the logistic growth curve (Wang et al, 2009;Zahedi and Jenner, 2003).…”

Cell membrane stability- an important criterion for selection of heat tolerant genotypes in wheat (Triticum aestivum L.)

“…In India, delay sowing shifts the grain filling during high temperature mean time which causes the shortening of grain filling period. Heat stress during the reproductive phase can cause pollen sterility, tissue dehydration and injuries of the photosynthetic apparatus diminish source activity and sink capacity, lower CO 2 assimilation and increased photorespiration (Harding et al, 1990, Wardlaw andMoncur, 1995;Zahedi and Jenner, 2003). Therefore, high temperatures spell during anthesis to grain filling and upto grain maturity than optimal temperature in delay planting, deteriorate the grain quality, reduces grain yield which may exceed to 40-50% (Joshi et al, 2007) because of the less time to utilize systematically natural resources.…”