Patterns of grain filling of spring and winter hexaploid triticales

Abstract

Eight hexaploid triticale genotypes, five of spring and three of winter growth habit were used to study the genetic variability of grain filling characteristics and their relationship with grain yield. Four trials were carried out under rainfed and irrigated conditions in Northeast Spain. Grain dry weight data was fitted to a logistic curve. Genetic variability existed for the length of the period from sowing to anthesis, maximum grain filling rate and maximum grain weight. Most of this variation was associated to the growth-habit of the genotypes. Winter triticales required 11% more thermal-time from sowing to anthesis, and had a maximum grain weight, which was 25% lower than that of spring genotypes. The maximum grain filling rate was 40% higher in spring than in winter triticales. Grain filling duration was mainly controlled by environmental conditions, and was not correlated with grain yield. A negative phenotypic correlation was detected between grain filling duration and maximum grain filling rate ( r p=−0.41, P<0.05), and a positive correlation between maximum grain weight and maximum grain filling rate ( r p=0.77, P<0.001). Spring genotypes yielded around 21% more than winter types, probably because they escaped from terminal water stress. Grain yield was strongly correlated phenotypically and genetically to the maximum grain weight ( r p=0.87, r g=0.92, P<0.001) and maximum grain filling rate ( r p=0.78, P<0.001; r g=0.79, P<0.05). Short duration from sowing to anthesis, high grain filling rate and high maximum grain weight seem to be major traits to optimise triticale grain yield under Mediterranean conditions.