中国玉米机械粒收质量主要指标分析

机械粒收是中国玉米生产技术的重大变革与发展方向,团队于2012—2019年在玉米主产区21个省(市区)布设了155个点次的粒收试验与示范,开展适宜机械粒收品种的筛选和粒收质量调查,共测试了865个玉米品种(组合),获取了2987组8961个机械粒收质量样本数据,分析表明,收获籽粒的平均含水率为25.91%,平均破碎率为7.96%,杂质率为1.18%,总损失率为3.54%,其中落穗损失占76.5%,是收获损失的主要部分。对比2012—2015年测试数据,近年我国玉米收获质量得到明显改善,其中,2015年以来收获期籽粒含水率平均每年下降0.78%、破碎率平均每年下降0.51%。与美国玉米收获质量相比,收获时籽粒含水率高9.5%,破碎率、杂质率也明显高于美国。收获质量指标间的相关分析表明,破碎率、杂质率均与籽粒含水率呈极显著正相关,籽粒含水率在19.06%时收获破碎率最低,收获期籽粒含水率高仍是籽粒破碎率高的主要原因。不同生态区间以黄淮海夏播玉米收获时籽粒含水率和破碎率最高、华北春玉米最低,西北和东北春玉米居中。进一步选育脱水快、收获时含水率低、后期站秆性能好的品种,推广品种脱水与区域气候配置技术,改进收获机械,并适期收获是降低破碎率、损失率的主要方向。

适宜机械粒收玉米品种的熟期评价指标

玉米收获期籽粒含水率偏高制约了机械粒收技术的应用,选育和筛选快速脱水的品种是解决这一问题的关键,然而我国尚缺乏评价籽粒脱水速率的指标。本研究于2014—2018年进行,在不同产区调查了先玉335和郑单958的生育和脱水进程,探讨玉米籽粒脱水速率的评价指标。结果表明,播种–生理成熟积温、播种–25%含水率积温和生理成熟–25%含水率积温在品种之间均差异显著。其中播种–生理成熟积温先玉335和郑单958平均为3039℃ d(2752~3249℃ d)和3090℃ d(2750~3546℃ d),差值51℃ d,变异系数为4%和6%。播种–25%含水率积温在这2个品种之间差异更大,先玉335和郑单958平均为3097℃ d(2920~3392℃ d)和3309℃ d(2980~3613℃ d),差值达212℃ d,变异系数为4%和5%。生理成熟–25%含水率积温先玉335和郑单958平均为66℃ d(0~287℃ d)和166℃ d(36~338℃ d),变异系数为131%和54%。播种–25%含水率积温更能体现品种之间籽粒脱水速率,可以作为现阶段机械粒收品种选育和筛选的熟期指标,但是该指标在区域、年份和播期之间有一定差异,在测量时建议统一田块和播种日期。本文提出用播种–25%含水率的积温作为评价籽粒脱水速率的熟期指标,用于当前品种选育和筛选,推动玉米机械粒收技术在国内的发展。

Study of corn kernel breakage susceptibility as a function of its moisture content by using a laboratory grinding method

The rate of corn kernel breakage in the grain combine harvesters is a crucial factor affecting the quality of the grain shelled in the field. The objective of the present study was to determine the susceptibility of corn kernels to breakage based on the kernel moisture content in order to determine the moisture content that corresponds to the lowest rate of breakage.In addition, we evaluated the resistance to breakage of various corn cultivars. A total of 17 different corn cultivars were planted at two different sowing dates at the Beibuchang Experiment Station, Beijing and the Xinxiang Experiment Station(Henan Province) of the Chinese Academy of Agricultural Sciences. The corn kernel moisture content was systematically monitored and recorded over time, and the breakage rate was measured by using the grinding method. The results for all grain samples from the two experimental stations revealed that the breakage rate y is quadratic in moisture content x,y=0.0796 x^(2)-3.3929 x+78.779;R^(2)0=0.2646, n=512. By fitting to the regression equation, a minimum corn kernel breakage rate of 42.62% was obtained, corresponding to a corn kernel moisture content of 21.31%. Furthermore, in the 90% confidence interval, the corn kernel moisture ranging from 19.7 to 22.3% led to the lowest kernel breakage rate, which was consistent with the corn kernel moisture content allowing the lowest breakage rate of corn kernels shelled in the field with combine grain harvesters. Using the lowest breakage rate as the critical point, the correlation between breakage rate and moisture content was significantly negative for low moisture content but positive for high moisture content. The slope and correlation coefficient of the linear regression equation indicated that high moisture content led to greater sensitivity and correlation between grain breakage and moisture content. At the Beibuchang Experiment Station, the corn cultivars resistant to breakage were Zhengdan 958(ZD958) and Fengken 139(FK139), and the corn cultivars non-resistant to breakage were Lianchuang 825(LC825), Jidan 66(JD66), Lidan 295(LD295), and Jingnongke 728(JNK728). At the Xinxiang Experiment Station, the corn cultivars resistant to breakage were HT1, ZD958 and FK139, and the corn cultivars non-resistant to breakage were ZY8911, DK653 and JNK728. Thus, the breakage classifications of the six corn cultivars were consistent between the two experimental stations. In conclusion, the results suggested that the high stability of the grinding method allowed it to be used to determine the corn kernel breakage rates of different corn cultivars as a function of moisture content, thus facilitating the breeding and screening of breakage-resistant corn.

Dynamics of maize grain drying in the high latitude region of Northeast China

A high grain moisture content at harvest has been an important problem in the high latitude region of Northeast China, and it is closely related to the genotypes of varieties, local meteorological factors and planting management. However, delayed harvest at a low temperature could not effectively reduce the grain moisture content. In this study, we continuously observed the grain drying during the late stage of different maturing types of maize varieties in Daqing, Heilongjiang Province, China in 2016 and 2017. A two-segment linear model was used to analyze the different stages of the drying processes: 1) Twosegment linear model fitting can divide the grain drying process of all varieties into two separate linear drying processes with different slopes. 2) During the rapid drying stage, the drying was faster at a higher temperature. The rate of slow drying was influenced by air vapor pressure. 3) The moisture content and meteorological factors when the drying rate turns from one stage into the other were not consistent between varieties and years. After entering the frost period, temperatures below 0℃ will significantly reduce the rate of grain drying. 4) Due to the short growth period of early-maturing varieties, the drying time was prolonged, and the grain moisture content was lower than that of the mid-late maturing varieties. Local meteorological conditions do not allow the drying of mid-late maturing varieties to achieve a lower moisture content. When the temperature falls below 0℃, the drying rate of grain decreases markedly. Therefore, one feasible way to solve the problem of high moisture content is to replace the early-maturing varieties and implement the corresponding cultivation techniques.

新疆生产建设兵团第四师71团玉米密植高产全程机械化生产技术模式发展调研

从种植品种、种植密度与种植方式、机械化作业和收储烘干等环节对新疆生产建设兵团第四师71团场玉米生产技术的发展进行调研。分析表明,71团场位于西北灌溉玉米区,通过规模化、标准化生产和统一作业管理,以密植增产为基础、子粒收获为核心、绿色防控与秸秆还田为保障构建的玉米密植高产全程机械化绿色生产技术,实现了高产和高效的协同提高与绿色可持续生产。经农业农村部专家指导组田间测产验收,2012年、2014年和2017年连续创造16701 kg/hm^2、18414 kg/hm^2和18447 kg/hm^2的全国玉米大面积(700 hm^2)高产纪录,净利润在15000元/hm^2以上,为现代玉米生产树立了成功的模式和样板。

辽北地区增密种植对玉米机械粒收质量的影响

2019年在辽宁省铁岭市铁岭县蔡牛镇和2019、2020年在昌图县老城镇开展大田试验,探索辽北地区增加种植密度对玉米机械粒收质量的影响。结果表明,供试品种种植密度由6.0万株/hm^(2)增加到7.5万和9.0万株/hm^(2),均表现出明显的增产趋势,其中最大增幅达15.11%。随着种植密度的增加,品种的生育期呈缩短、收获期子粒含水率呈下降趋势,其中子粒含水率下降幅度为0.1~2.6个百分点。增加种植密度对收获子粒的破碎率、杂质率和损失率没有显著影响。由此可见,在辽北地区增加玉米种植密度不仅增产,而且能够降低收获期子粒水分、有利于机械粒收。

河西内陆灌区粮饲通用玉米超高产栽培优化农艺措施研究

采用4因素5水平二次通用旋转组合设计,探索河西内陆灌区粮饲通用玉米超高产栽培优化农艺措施,研究密度(X1)及氮肥(X2)、磷肥(X3)、钾肥(X4)主要栽培因子对耐密抗倒玉米正德305产量的影响,建立产量与4个因素之间的回归数学模型。通过模型解析寻优表明,4个因素对玉米产量效应的主次为氮肥>密度>钾肥>磷肥,且密度和氮肥对产量的影响显著。本试验条件下,获得产量≥16000 kg/hm^(2)的最优农艺措施方案,密度10.1万~10.8万株/hm^(2),施N量264.3~289.95 kg/hm^(2),施P_(2)O_(5)量155.48~187.8 kg/hm^(2),施K_(2)O量152.6~166.5 kg/hm^(2)。高产创建示范田验证表明,构建的模型准确,可为玉米超高产栽培提供技术支撑。