Abstract
A high grain breakage rate is the main problem that occurs during mechanical maize harvest in China. The breakage sensitivity of different varieties was significantly different, and the breakage resistance is heritable. Therefore, breakage resistant variety screening can help improve the field production efficiency and provide references for breeding work. In this study, 42 varieties of maize were harvested with the same mechanical parameters and the same manipulator on a range of harvest dates at experimental stations in Xinxiang, Henan Province, in 2017 and Changji, Xinjiang Province, in 2018 to determine the sensitivity of grain moisture content on grain breakage rate during machine harvest for different varieties. The integral value of the grain breakage rate curve corresponding to the range of 15% to 30% grain moisture content was used as an index that expressed the sensitivity of maize grains to breakage depending on grain moisture content (BSW). Forty-two varieties were categorized as having weak, intermediate, or strong BSW. Among the same four varieties in the two stations, Lianchuang 825 and Lianchuang 808 were classified as sensitive and fragile varieties, Shandan 650 was classified as an intermediate variety, Zeyu 8911 was divided into weak sensitive and breakage-resistance varieties in Xinxiang and intermediate varieties in Changji. The BSW classification results at the two experimental sites were generally consistent, indicating that breakage sensitivity due to moisture content may be a relatively stable genetic characteristic. This study suggested that the integral method for determining BSW can be used to assess the resistance of different maize varieties to grain breakage during mechanical harvesting. The integral method was used to identify twelve breakage-resistant varieties in Xinxiang Station, and six breakage-resistant varieties in Changji Station. This study provides a method for screening maize varieties that are suited to mechanical grain harvesting and for studying the mechanisms of grain breakage resistance. Keywords: maize, mechanical grain harvest, breakage resistance, integral method, varieties classification DOI: 10.25165/j.ijabe.20201305.6037 Citation: Wang Y Z, Li L L, Gao S, Guo Y N, Zhang G Q, Ming B, et al. Evaluation of grain breakage sensitivity of maize varieties mechanically-harvested by combine harvester. Int J Agric & Biol Eng, 2020; 13(5): 8–16.
Highlights
Modern maize production in China is progressing toward complete mechanization, but mechanized harvesting, especially grain harvesting, currently presents a bottleneck in the production process[1,2,3,4]
In 2017, 28 maize hybrids were selected as experimental materials for Xinxiang Station (Table 1) from among hybrids that were already adapted to the location
In 2017, 28 maize varieties were harvested from the Xinxiang Station between October 6 and November 25
Summary
Modern maize production in China is progressing toward complete mechanization, but mechanized harvesting, especially grain harvesting, currently presents a bottleneck in the production process[1,2,3,4]. Even when the grain moisture content is the same, different maize varieties will experience different breakage rates[10,11,12,13,14,15,16,17]and breakage resistance is heritable[6,17,18,19]. Many indexes and methods have been developed for determining maize kernel susceptibility to breakage. Methods for determining BS can be classified into four categories based on the different external forces applied to grain and contact position. These include grain impacts against non-grain surfaces, grain-on-grain impacts, rubbing impacts, and centrifugal impacts[22,23]. The instruments used to determine BS are typically the Wisconsin breakage tester and the Stein breakage tester[24]
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