Growth and Development of Logan (Dimocarpus longan Lour.) fruit cv Daw In Nakhon Si Thammarat Province

Abstract

Fruit growth and development of longan (Dimocarpus longan Lour. cv. Daw) were studied in the longan orchard at Thasala district, Nakhon Si Thammarat province area from August 2006 to March 2007. The objectives were to investigate fruit growth pattern and time of fruit maturity for harvesting in southern environmental conditions. Fruit growth of longan was found as simple sigmoid curve and was devided into four stages. The first period was from flower opening to 60 days after anthesis, fruit fresh and dry weights increased slowly as an development of rind and seed.  The second period from 75 to 120 days after anthesis, the fruit weights increased rapidly as an  development of all parts; rind aril and seed including a rise of total soluble solids (TSS).  The third period from 120 to 150 days after anthesis, the fruit weights increased slowly and reached the maximum on 150 day after anthesis. While TSS was the highest on 135 days after anthesis. The fourth period from 150 to 180 days after anthesis, the weights and TSS decreased gradually.  The maturity of fruit for harvesting began from 135 day after anthesis. At this stage the heat summation of longan fruit was 2,193 degree days, the fresh weight 9.79 grams with accounted for rind, aril and seed 19.82, 68.39 and 11.80% respectively, while the TSS was 21.79^๐Brix.