Genetic control of vegetative growth index in oats (Avena spp.)

Vegetative growth index of cereals is defined as the mean quantity of vegetative tissue produced per unit land area per day. Thus, increasing vegetative growth index is a route by which biomass yield can be increased. The proportion of biomass that is translocated to grain is defined as harvest index. In midwestern USA, where harvest index of oats is optimum at ca. 45% and growth duration is restricted to 100-110 days by high temperature, diseases, and drought, breeding for higher vegetative growth index has been proposed as a way to increase grain yield potential for new cultivars.Twelve matings involving Avena sterilis-derived lines and A. sativa cultivars were used to study vegetative growth index. F2-derived lines from these matings were evalutated for vegetative growth index in microplots in field experiments in three environments with four replicates per environment. Vegetative growth index was found to be a quantitatively inherited trait. Heritability values for this trait averaged 54% when the unit of measurement was a microplot. Additive genetic control for vegetative growth index was indicated in seven matings, but in the remaining five, nonadditive gene action was involved in the inheritance patterns. High vegetative growth index segregates were produced more frequently from matings among unrelated parents than from matings of related ones.