Milling and Shedding Variability of Rice Plant at Harvest Season
Alireza Allameh *
Rice Research Institute of Iran (RRII), Agricultural Research, Education and Extension Organization (AREEO), Rasht, Iran.
Shabab Nemati Chali
Agricultural Engineering Research Institute (AERI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran.
*Author to whom correspondence should be addressed.
Abstract
The quality and yield of all cereal crops are the main objectives of farming operations. Different factors have been enumerated which have had significant effects on these properties. Among them, grain shattering is recounted as an impressive parameter that directly influences on quantity and quality of rice. To identify the variations of grain yield and its milling properties, a two-year study was conducted to assess the impact of grain shattering on them. Factorial experiment arranged by a completely randomized design with five repetitions. The independent variables assigned as rice cultivars at three levels (Hashemi, Gilaneh, and Anam), followed by harvest date at five levels (26, 28, 30, 32, and 34 days after 50% flowering), and grain place on the panicle at three levels (upper, middle, and basal). The dependent variables were chosen as the separating force of grain from its pedicel and milling properties. Data analysis demonstrated that the separating force differed significantly among rice cultivars. The maximum mean force (1.18 N) was obtained when Hashemi harvested at 26 DAF but the minimum force (0.11 N) was related to Anam harvested at 34 DAF. The effect of the year was significant (P = 0.01) owing to late planting in the first year. The separating force illustrated a reduction trend from the first to the last date of harvesting intervals for both study years. It was 9, 7, and 10 percent for Hashemi, Gilaneh, and Anam, respectively. Since an individual panicle does not ripen evenly, those grains of basal required more detaching force than the upper. An increase of 36, 57, and 51 percent were observed for Hashemi, Gilaneh, and Anam, respectively. Natural shattering went up about 0.049, 0.081, and 0.112 percent for Hashemi, Gilaneh, and Anam, respectively for trial intervals. Late planting in the first year impressed the head rice yield significantly so that cultivars experienced a rise of 6-10 percent in the second year. It is suggested that the optimum harvest date for rice cultivars would be 30 DAF overall.
Keywords: Rice, yield, quality, shedding, harvest season, head rice yield