The effect of potassium application on specific leaf area of East African highland bananas
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Bananas (Musa spp) is among the most important food crops in Uganda. Productivity is greatly limited by drought stress and potassium, which also mitigates drought stress in East African highland bananas. LINTUL-BANANA II to simulate water-limited growth and yield of banana. It can be extended to include potassium-limited growth and yield to illuminate pathways for developing cost effective management practices. It is not known if potassium nutrition affects the specific leaf area of East African highland banana plants, which in LINTUL-BANANA II is assumed to be constant at a given growth stage. This study was carried out at the National Agricultural Research Laboratories in an ongoing potassium response trial set in a completely randomized block design. Plants were selected from the treatments that received 0, 250 and 600 kg K ha-1 yr-1 . Destructive sampling was done to collect samples for determining leaf area and leaf dry matter at three growth stages. Data were analysed using ANOVA with plant growth stage as a covariate to adjust for size dependency. Total leaf Area per ranged from 0.2 to 10.4m2 from treatment with 0 kg k ha-1 yr-1 and the mean leaf area per plant per year was about 3M2 . The specific leaf area at individual plant level ranged from 62 cm2 g-1 for plants that received 600 kg ha-1 yr-1 to 192 cm2 g-1 for plants that received 0 kg ha-1 yr-1 . There was a noticeable reducing trend across the K application rates. However, application of K had no significant effect on specific leaf area of banana at plant level. At individual leaf level, application of K significantly reduced specific leaf area from 120 cm2 g to about 100 cm2 g. Leaf dry matter ranged from 17.4 to 1262 g plant-1 . At plant level, application of K had no effect on the lamina dry matter. Application of 600 kg K ha-1 yr -1 almost doubled the midrib dry matter compared to that for plants that received 0 and 250 kg K ha-1 yr-1 but this effect was not significant. Potassium had no significant effect on leaf area per plant. High K application increased both leaf lamina dry matter and midrib dry matter at individual leaf level but leaf midrib dry matter has 100% increment while leaf lamina dry matter increases by only 30%.There is no significant effect of K application on the specific leaf area per plant, however there is a significant effect of high K application on specific leaf area at leaf level. This study needs to be repeated on plants that were not drought stressed and sufficient sample size for robust conclusions on the set objectives. Key words: Leaf dry matter, leaf lamina, leaf mass ratio, midrib Musa acuminata, Uganda.