The effect of nitrogen and potassium fertilization on growth, yield and quality of starfruit (Averrhoa carambola L.)
1996
Izham Ahmad | Zabedah Mahmood
A field experiment was established at MARDI, Serdang, Selangor to determine the optimum supplies of nitrogen and potassium for the vegetative growth and early fruit production of starfruit (Averrhoa carambola L.) cultivar B10 trees. Data was collected for an experimental period of 4 years. A combination of low level of N and high level of K was beneficial for the early vegetative growth and fruit production. The optimum combinations of N and K2O for the first, second, third and fourth years of growth and fruit production were 0.2 kg N and 0.6 kg K2O, 0.3 kg N and 1.6 kg K2O, 0.6 kg N and 3.2 kg K2O, and 0.8 kg N and 4.8 kg K2O per tree per year respectively. Very high combinations of N and K were found to decrease rather than increase yield. Measurements of leaf water potential, photosynthesis rate and stomatal conductance suggested that these excessive fertilizer treatments exposed the plants to intermittent osmotic shocks.
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