Thesis Abstract of AGS Students

Rasee Rodpradub (1997)

The first year mango trees grown in rainfed upland always died at the high rate. The study was then carried out to evaluate the effect of water application, N-fertilizer and age of grafted material on survival and growth of the first year mango trees as well as to assess economic aspects of the management practices. A field experiment was conducted on-farm at the Chom Tong Land Reform Area, King-Amphur Doi Lor, Chiang Mai Province during August 1994 to December 1995. The experiment consisted of three factors, arranged in a split-split-plot design with two watering intervals (i.e. 2 liters/tree/4weeks and 2 liters/tree/2 weeks) as the main plot, two rates of N-fertilizer application (i.e. 0 and 75 gN/tree) as the subplot and three ages of mango grafted seedlings cultivar ‘Chok-A-Nan’ (i.e. 2 months, 1 and 2 years) as the sub-subplot.

The result showed that 60 % of mango trees survived under field experiment. Water application and N-fertilizer treatments did not show significant difference in survival rate and growth. In contrast, the use of 2-month and 1-year-old grafted seedlings exhibited higher survival rate than 2-year-old grafted seedlings. Similar result was found for accumulative stem diameter and plant height growth rate. Root depth, measured 15 months after planting, showed high variation, ranging from 64-124 cm. The character was positively correlated with survival rate. Accumulative stem diameter and plant height growth rate also highly correlated with survival rate. Leaf total nitrogen analyzed 3 months after planting was found to be 1.8 %, and it decreased to 1.4 % after the August shoot flush, 13 months after planting. Chlorophyll content in mature leaves as well as the changes of leaf water potential were similar for all treatments.

The proper management practice for reducing the mortality loss included the use of 2-month-old grafted seedlings, no N application and watering at least 2 liters/tree/4 weeks. Such practice had an added cost of 64.3 baht/surviving tree.

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