MORPHOLOGICAL CRITERIA OF MATURITY PHYSIOLOGY IN WHEAT

Abstract

A study was performed at Chapingo, México in order to identify morphological indexes of grain  physiological maturity in wheat (Triticum aestivum L.). Fifteen cultivars contrasting in plant height, earliness and in awn presence, were evaluated in two experiments. In the first one, under field conditions, 9 maturity criteria, based upon the loss of green color in spikelet and peduncle were compared, plus two checks: five and ten days after color loss in the spikelet. In the second one, carried out under laboratory conditions, seed germination and seedling vigour were evaluated and related to the criteria included in the first experiment. Results from the first experiment indicated that green color loss in the rachis was the best indicator of kernel physiological maturity (PM), assuming that PM is reached when grain accumulates its maximum dry weight; PM occurred 45 days after anthesis as an average of the 15 cultivars. In the second experiment, highest germination percentages (above 90%) were obtained from seeds harvested 25 days after anthesis; besides, the longest values of radicle, plumule and seedlings, were obtained from seeds harvested 36 days after anthesis. It is then suggested that the embryo physiological maturity occurs before the maximum kernel dry weight is obtained.