Growth responses of potato (Solanum tuberosum) grown in a hot tropical lowland to applied paclobutrazol: 1. Shoot attributes, assimilate production and allocation

Abstract

The growth responses of potato (Solanum tuberosum) to leaf and soil applied paclobutrazol (PBZ) under the hot tropical climate of eastern Ethiopia was investigated in two field experiments. A month after planting, PBZ was applied as a foliar spray or soil drench at rates of 0, 2, 3, and 4 kg active ingredient (a.i.) PBZ/ha. A randomised complete block design with three replications was used. Regardless of the method of application, PBZ increased chlorophyll a and b content and net photosynthesis of the leaf tissue, but reduced shoot growth, plant height, stomatal conductance, and rates of transpiration compared with the control. PBZ significantly delayed the onset of leaf senescence and increased the partitioning of assimilates to the tubers while reducing assimilate supply to the leaves, stems, roots, and stolons. PBZ improved the productivity of potatoes grown in a hot tropical climate by reducing shoot growth, increasing leaf chlorophyll content, enhancing the rate of photosynthesis, improving water use, and modifying partitioning of dry matter to the tuber.