Enzymatic activities, carbohydrate partition and growth in cotton progenies selected for high and low starch content in the roots

Abstract

Two selections for high and low starch content in the cotton (Gossypium hirsutum L.) roots and the original population were studied in a greenhouse experiment. In the high root starch population.amylolytic activities in the leaves were increased, and decreased in the low starch population facilitating the export of assimilates in the former and reducing it in the later. In the stem â-amylase increased in the low starch population, and in roots it was the invertase activity that iitcreased in the low starch population. These activities in stems and roots are linked with a decrease of starch content and represent the low availability of assimilates in the low starch selection.These genetic manipulations resulted in changes in the growth of both selected populations, being reduced in the high starch and increased in the low starch selections, whereas earliness of fruiting and reduction in the leaf area occurred in the high starch and the oposite result in the low starch population. The importance of these changes for drought resistance is discussed.