Thesis Abstract of AGS Students

Factors influencing yield of upland rice grown under highland condition

Arkom Kanjanaprachote (1988)

The study on the factors influencing the upland rice yield was conducted at the Khun Pae Royal Project site, Chom Tong district, Chiang Mai, with the karen hilltribe. The initial study involved the agro-ecosystem analysis to identify the farm level constraints to high rice yields. The study indicated that the cultivation area was low in soil phosphorus (8.8 ppm). Farmers planted land races of upland rice and the average yield was 47 percent lower than the improved varieties. Farmers did not apply any chemical fertilizer. In addition the land use planning would promote reforestation and in consequence would reduce the cultivation area from 66 percent to 34 percent. This would decrease the total rice production. The problem to self-sufficiency in rice production was intensified as the population was increasing at the rate of 5 percent.

The study was then followed by on farm testing on proven upland rice technologies which included improved variety, fertilizer application and planting method. Each factor consisted of two levels: the improved and the farmer's technology. The factorial experiment with three sets of arrangement namely, complete, mini- and supplementary were conducted with 15 farmers in a ratio of 3:3:9 respectively. The results showed that the improved technology yielded 182 kg/rai more than the farmer's. The contribution of each factor to the significant yield difference due to variety, fertilizer was 114, and 83 kg/rai, respectively. The joint contribution of two factors such as variety x fertilizer and variety x planting method provided additional yields of 191 and 96 kg/rai, respectively, while the joint contribution of fertilizer x planting method was not significant. The cost and return analysis showed that the improved variety had the added profit of 343 Baht/rai, while the application of chemical fertilizer caused the loss of 64 Baht/rai. The added profits from the use of variety and chemical fertilizer, variety and planting method were 259 and 265 Baht/rai, while the use of chemical and planting method would have the deficit of 231 Baht/rai. The added profit of the new package technology was 225 Baht/rai. Therefore it was apparent that changing to a new rice variety would be better alternative to improve the yield of upland rice at the Khun Pae site.

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