Head Rice Yield of Crops Harvested by Combine and Hand at Different Ripening Times in Cambodia

Abstract

SUMMARYExperiments were conducted across 2 years to determine the effect of harvesting methods – combine harvester and hand harvesting – and harvest time during ripening on milling quality of long grain rice grown in the rainfed lowland ecosystem in Cambodia. Head rice yield (HRY) was highest when rice was harvested 25 days after flowering and decreased with delay in harvesting at 35 and 45 days after flowering. This was accompanied by a general decline in grain moisture content at harvest, although it was still high at 24–25% at 35 days after flowering. The decline in HRY was associated with increases in fissured grain percentage observed immediately after harvest. Hand harvesting produced 2–6% higher HRY than combine harvesting. Fissured grain in hand harvested crops was lower in year 1, but was similar to combine harvested crops in year 2. Both hand and combine harvested crops were sun-dried but rough rice harvested by combine was dried on plastic sheet and this may have contributed to reduction in HRY. Maximum HRY percentage was only about 44% and the factors contributing to this low HRY were discussed. Harvesting time and methods had no significant effect on grain yield, but the field grain loss during the harvesting operation was 2–5% higher in combine than hand harvesting.

Effects of introduction of combine harvester and flatbed dryer on milling quality of three glutinous rice varieties in Lao PDR

“…Although HRY was significantly higher in combine harvested crops in WS and in hand-harvested crop in DS, the difference was rather small in both seasons. Bunna et al (2018) found slightly higher HRY in handharvested crops than in combine harvested crops in WS in Cambodia. Combine harvesting results in similar grain yield with only slightly higher grain loss in the field than hand harvesting, but when grain loss during threshing is added, the total grain loss is similar between the two harvesting methods (Bunna et al, 2018).…”

“…Bunna et al (2018) found slightly higher HRY in handharvested crops than in combine harvested crops in WS in Cambodia. Combine harvesting results in similar grain yield with only slightly higher grain loss in the field than hand harvesting, but when grain loss during threshing is added, the total grain loss is similar between the two harvesting methods (Bunna et al, 2018). Farmer's net return is greater with combine than with hand harvesting as long as the combine contractor fees are less than 20% of the total rice harvested (Xangsayasane et al, 2019).…”

“…The combine harvester has higher speed to harvest grain resulting in more damage grains and slightly lower HRY (Andrews, Siebenmorgen, Vories, Loewer, & Mauromoustakos, 1993). Bunna et al (2018) also found slightly higher HRY in hand-harvested crops than in combine harvested crops in WS in Cambodia. However, their work was conducted on non-glutinous rice, and also their sun drying conditions were different for combine and hand-harvested crops.…”

“…The rice quality is mainly determined by physical and chemical indices including amylose content (Juliano, 1985). Milling quality particularly head rice yield (HRY) has become important with the increased commercialization and marketing of rice in Lao PDR and neighbouring countries such as Thailand, Vietnam and Cambodia while it was not a major concern to rice farmers in subsistence agriculture (Bunna et al, 2018). Milling quality of rice grown during the DS is particularly difficult to maintain as the crop is harvested in late April or early May and often encounters early rain and proper drying is required (Juliano & Duff, 1991).…”

“…Combine harvesting service is spreading in Central Laos as it provides higher CONTACT Darunee Jothityangkoon darcho@kku.ac.th return to farmers compared to traditional hand harvesting (Xangsayasane et al, 2019). Combine grain loss in the field is comparable to hand-harvested crops when grain loss during threshing is added to that harvested by hand (Xangsayasane et al, 2019;Bunna et al, 2018). The combine harvester has higher speed to harvest grain resulting in more damage grains and slightly lower HRY (Andrews, Siebenmorgen, Vories, Loewer, & Mauromoustakos, 1993).…”