Effects of supplemental fertigation levels on the growth and nutrient composition of pot-grown persimmon (Diospyros kaki) trees with a high crop load
Supplemental nitrogen (N) and potassium (K) fertilization is of critical importance for maintaining tree vigor and producing high-quality fruits in persimmon (Diospyros kaki), especially under high fruit-load conditions. This study was conducted to determine the effects of four different fertigation levels on pot-grown trees with two different leaf:fruit (L:F) ratios. On July 1, the L:F ratios of 3-year-old 'Fuyu' persimmon trees were adjusted to 20 and 10 through fruit thinning. From early July to early September, the trees in each pot were fertigated with a solution containing no (0 N and 0 K), low (10 N and 7.5 K), medium (20 N and 15 K), or high (30 N and 22.5 K) levels of supplemental N and K. The trees with an L:F ratio of 10 had higher yields but smaller fruits with lower soluble solids than fruits from trees with an L:F ratio of 20. Increasing the fertigation level did not significantly affect fruit size in trees with an L:F ratio of 10, but fruits had lower skin color values and soluble solids. A low L:F ratio led to lower amounts of soluble sugars in dormant shoots, which was true even under higher fertigation levels. N concentrations in the shoots of the low L:F trees were significantly greater under higher levels of fertigation. However, increasing the fertigation level resulted in severe cold injury to dormant shoots in trees with both L:F ratios, although it also increased the number of flower buds produced the following year. It was concluded that an excessive supply of supplemental N and K to trees with a high crop load should be avoided because of the unfavorable results.
Choi, S.T., Kim, S.C., Ahn, G.H., Park, D.S., Kim, E.G. and Kim, E.S. (2018). Effects of supplemental fertigation levels on the growth and nutrient composition of pot-grown persimmon (Diospyros kaki) trees with a high crop load. Acta Hortic. 1195, 111-118
cold injury, leaf-to-fruit ratio, nitrogen, potassium, storage reserves