Document Type : Research Paper
Abstract
Multistage and semi-mechanized harvesting of rice in Khouzestan province, Iran, causes much loss. Depending on available facilities and conditions, either spike-tooth or rasp-bar cylinders are employed with either direct or indirect combine harvesting methods. The present research studied the effect of these different harvesting methods on the amount of losses in two rice varieties in 2001-2002 at Shavour Agricultural Research Station in Khouzestan province. The experiment was devised as a strip-plot with a randomized complete block design with two variables (harvesting method, variety) and three replications. The vertical axis variable harvesting methods were: indirect harvesting (manual) plus threshing by rasp-bar cylinder combine; indirect harvesting plus with threshing by spike-tooth cylinder combine; direct harvesting with threshing by rasp-bar cylinder combine, direct harvesting with threshing by spike-tooth cylinder combine. The horizontal axis variables were: high yield LD183 rice variety; qualitative local Red Anboury rice variety. Analysis of the losses for the two years showed a significant difference between years for harvesting methods and their interactions but no significant difference between varieties. A comparison of averages showed that losses for the first year were greater at 3.34% than for the second year at 2.08%. However, average losses for the Red Anboury variety were 2.71% and 2.74% for the LD183 variety. For both direct and indirect harvesting methods, average losses for harvesting by spike-tooth cylinder combine were 1.73%, which was less than the 3.68% for the rasp-bar cylinder combine. The spike-tooth cylinder combine produced the least amount of loss over the two varieties. Indirect harvesting of LD183 with threshing by rasp-bar cylinder combined in the first year produced the greatest average loss at 5.42%. Indirect harvesting of Red Anboury with threshing by spike-tooth cylinder combine in second year produced the lowest average loss at 1.48%. There was no significant difference between harvesting methods for quality of loss (broken rice rate) but there was a large significant difference by year with 45.6% for the second year and only 18.9% for the first year. This loss was also significant by variety with LD183 averaging 34.2% broken rice and Red Anboury averaging 27.6%. Over all harvesting methods, LD183 had greater broken rice rates.
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