Changes of Mineral Nutrients in Leaf, Panicle and Fruit Cluster of “Daw” Longan from Early Anthesis to Fruit Maturation

Abstract

Analysing the 2^nd compound leaves of longan cultivar “Daw” behind the panicle-fruit cluster and the panicle-fruit cluster at one month interval from anthesis (March) to fruit maturation (August) found that, In the leaves; Nitrogen (N)was high (1.80%) at anthesis, decreased during fruit development and reached the lowest point (1.46%) at fruit maturation. In contrast Calcium (Ca) and Magnesium (Mg) increased as the time progress. Zinc (Zn) increased at the first stage of fruit set (April-May) and decreased at aril formation (June-August). Iron (Fe) increased during the month of May and June and again in August. Phosphorus (P), Potassium (K), Manganese (Mn) and Copper (Cu) remained steady thoughout the period of fruit development. In the flower panicle-fruit cluster; N and P had tendency of decreasing at fruit set (April) and attained the lowest value at fruit maturation (August). Ca was the lowest (0.78%) at anthesis, increased sharply to 1.34% at fruit set and remained at that level until fruit maturation. K decreased significantly during aril formation and stayed at that low level until maturation. Mg, Mn and Cu decreased and stayed unchanged after fruit set. Zn decreased during May-July but increased again at maturation. Fe was relatively unchanged (91-152 ppm.) during fruit development but increased drastically to 411 ppm at maturation.

In general, the amount of N, P and K in the panicle-fruit cluster were higher than those found in the leaves while the amount of Ca, Mg and Mn were higher in the leaves than in the panicle-fruit cluster.