The priority of management factors for reducing the yield gap of summer maize in the north of Huang-Huai-Hai region,China

Understanding yield potential, yield gap and the priority of management factors for reducing the yield gap in current intensive maize production is essential for meeting future food demand with the limited resources. In this study, we conducted field experiments using different planting modes, which were basic productivity(CK), farmer practice(FP), high yield and high efficiency(HH), and super high yield(SH), to estimate the yield gap. Different factorial experiments(fertilizer, planting density, hybrids, and irrigation) were also conducted to evaluate the priority of individual management factors for reducing the yield gap between the different planting modes. We found significant differences between the maize yields of different planting modes. The treatments of CK, FP, HH, and SH achieved 54.26, 58.76, 65.77, and 71.99% of the yield potential, respectively. The yield gaps between three pairs: CK and FP, FP and HH, and HH and SH, were 0.76, 1.23 and 0.85 t ha~(–1), respectively. By further analyzing the priority of management factors for reducing the yield gap between FP and HH, as well as HH and SH, we found that the priorities of the management factors(contribution rates) were plant density(13.29%)fertilizer(11.95%)hybrids(8.19%)irrigation(4%) for FP to HH, and hybrids(8.94%)plant density(4.84%)fertilizer(1.91%) for HH to SH. Therefore, increasing the planting density of FP was the key factor for decreasing the yield gap between FP and HH, while choosing hybrids with density and lodging tolerance was the key factor for decreasing the yield gap between HH and SH.     

大型组合式机械通风玉米穗储粮仓的设计

本研究针对大农户玉米穗储藏的实际情况，研制了大型组合式机械通风玉米穗储粮仓，并对其进行了装粮试验。结果表明：该型储粮仓机械性能稳定，结构组装方便，降水、防霉、防鼠效果显著，可有效降低粮食产后损失，保证粮食品质。 [关键词] 粮仓|玉米穗|机械通风     

基于WOFOST模型的辽宁省春玉米干旱灾损风险评估

利用锦州农业气象试验站的作物生长发育和土壤实测数据对WOFOST模型水分胁迫模块进行了调参，适用性验证表明，WOFOST模型适用于辽宁省春玉米生长发育和产量的模拟，辽宁省春玉米受干旱的影响可以利用WOFOST模型较敏感地反映出来。利用调参后的WOFOST模型模拟了全生育期及出苗~拔节、拔节~抽雄、抽雄~乳熟和乳熟~成熟各阶段发生轻、中、重旱情景对辽宁省春玉米产量的影响，并根据模拟结果确定了不同干旱风险等级下辽宁省东、中、西部玉米生产的灾损范围。结果表明：不同生育期发生干旱对产量的影响不同，总体上，抽雄~乳熟期发生干旱的影响最大，其次是拔节~抽雄期，而出苗~拔节期和乳熟~成熟期发生干旱对产量的影响较小，全省春玉米在抽雄~乳熟期发生重旱的减产风险达30%~70%；在相同干旱水平下，不同区域受影响程度也不同，在全生育期及各生育阶段发生轻、中、重旱情景下，干旱导致的减产率总体上表现为由东部向西部地区逐渐加重的趋势，在全生育期重旱情景下，辽宁省东部的春玉米减产率为40%~75%，中部为60%~90%，西部达65%~95%。     

球孢白僵菌-玉米共生体对亚洲玉米螟取食行为的影响

为明确球孢白僵菌-玉米共生体对亚洲玉米螟幼虫取食行为及取食选择性的影响，本文通过室内控制试验，采用培养皿叶盘法，研究了共生体对亚洲玉米螟初孵幼虫和3龄幼虫的选择、非选择性取食的影响。结果表明，在48 h非选择性试验中，亚洲玉米螟初孵幼虫在球孢白僵菌-玉米共生体叶片组织（处理组）上的取食率显著低于未接种球孢白僵菌玉米叶片（对照组），第48 h时在共生体和对照玉米上的幼虫取食率分别为35.7%和62.5%，差异极显著；3龄幼虫在共生体茎秆组织上的取食率与对照组玉米差异不显著。在48 h选择性试验中，初孵幼虫在共生体玉米叶片组织上的取食率显著低于对照组，共生体玉米叶片组织上的幼虫取食率随时间的增加呈下降趋势，第48 h时在共生体和对照玉米上的幼虫取食率分别为6.3%和20.6%，差异极显著；3龄幼虫在共生体和对照组玉米茎秆组织上的幼虫取食率随时间的增加呈上升趋势，其中对照组幼虫取食率显著高于处理组，第48 h时在处理组和对照组玉米上的幼虫取食率分别为33.1%和45.6%，差异极显著。本研究初步表明，球孢白僵菌-玉米共生体对亚洲玉米螟幼虫的取食行为有显著的抑制和忌避作用。     

基于卷积神经网络的玉米病害识别方法研究

为解决传统的玉米病害识别方法中特征提取主观性强及误识率高的问题,提出利用卷积神经网络对玉米病害进行识别。以玉米病害图像和健康图像共5种类别的玉米图像为研究对象,并采用LeNet模型进行试验。首先,按照8∶2的比例为每种玉米病害图像选择训练集和测试集。然后,通过试验组合和对比分析的方法比较不同卷积神经网络结构设置对准确率的影响,选出最佳参数。另外,选用Adam算法代替SGD算法来优化模型,通过指数衰减法调整学习率,将L2正则项添加到交叉熵函数中,并选择Dropout策略和ReLU激励函数。最后,确定了一个10层CNN网络结构。试验结果显示,玉米花叶病、灰斑病、锈病、叶斑病和玉米健康识别率分别为95.83%、90.57%、100%、93.75%、100%,平均识别率达96%,平均计算时间为0.15 s。经试验结果比较,该模型识别效果明显高于传统方法,为玉米病害的防治提供技术支持。     

耐低温耐低氧萌发野败不育系赣野A的选育

赣野A是江西省农科院水稻研究所将东乡野生稻的耐冷性和耐低氧萌发能力导入抗稻瘟病保持系赣香B后再与赣香A测交和回交育成的野败型三系籼稻不育系。该不育系败育彻底,异交结实率高,配合力较强,具有较强的耐冷性和耐低氧萌发能力,在直播杂交稻育种中应用前景广阔。2019年通过了江西省品种审定。     

Maize harvest index and water use efficiency can be improved by inhibition of gibberellin biosynthesis

Possibilities to improve maize harvest index and nutrient utilization efficiency by application of plant growth regulators were investigated. In container experiments, the effects of different growth regulators on the development of the maize (Zea mays L.) cultivars Pioneer 3906 and Fabregas were tested. Paclobutrazol (PAC) and chlorocholine chloride (CCC), two inhibitors of gibberellin biosynthesis, as well as gibberellic acid (GA₃) were applied at growth stage V5. Three weeks after application of PAC, shoot growth of both maize cultivars was strongly affected with a significant decrease in plant height in the PAC treatment by 44% and 36% for Pioneer 3906 and Fabregas, respectively. The growth‐retarded plants had higher leaf areas and reduced transpiration rates. The higher shoot growth after GA₃ application was accompanied by a reduction in leaf area and an increase in transpiration rate during 1 week before anthesis. CCC treatment showed no significant effects on plant height, leaf area and transpiration rate. The PAC‐treated cultivar Pioneer 3906 produced several cobs per plant, which were mainly barren at maturity. However, PAC application to Fabregas resulted in just one cob per plant with good kernel development and a grain yield, which was not significantly reduced in comparison with the control. With this similar grain yield in combination with a straw yield decrease of 32%, the harvest index was significantly improved by 12%. In addition, with PAC‐treated Fabregas plants, a 19% increased water use efficiency of the grain (WUE_grain) during the critical period of kernel setting was achieved. In this maize cultivar, CCC application also improved harvest index by 5%, but no effect on WUE_grain occurred. GA₃ treatment decreased harvest index of both maize cultivars, and it either reduced WUE_grain (Pioneer 3906) or showed no effect (Fabregas). Utilization efficiencies of N, P and K were not increased with growth regulator application, even in the PAC‐treated Fabregas plants with a significantly improved allocation of assimilates to the grain, mirrored by the higher harvest index. The results indicate that fertilizer applications must be adjusted to the reduced demand of growth‐retarded plants, most likely leading to higher nutrient utilization efficiencies.     

厚皮甜瓜新品种红宝玉的选育

红宝玉是以10R15 为母本、10R8 为父本选育而成的中熟厚皮甜瓜一代杂种。植株长势稳健，抗病抗逆性强。全生育期95～110 d（天），果实发育期30～35 d（天）。果实短椭圆形，成熟后果面乳白色，单果质量约1.5 kg，果肉橘红色，肉厚3.5～4.0 cm，腔小不发酵，中心可溶性固形物含量17.5%，肉质紧脆，不脱蒂，耐贮耐运。平均每667 m²产量3 600 kg 左右。适宜在山东、河北、陕西、安徽等地春季保护地设施栽培。     

杂交稻低播量精量播种育秧及机插取秧特性

【目的】明确杂交稻70 g以下低播量精量穴播和条播对育秧效果及机插特性的影响,突破生产中杂交稻机插的技术瓶颈。【方法】以中浙优1号和甬优1540两个杂交稻品种为材料,利用机插标准9寸盘,设置机械穴播和条播两个精量播种方式,并以机械流水线撒播为对照,穴播规格为16(纵向)×34(横向)穴,条播为纵向16条,以穴播5粒、3粒及2粒的播种量进行播种试验。考查了低播量下不同播种方式对秧苗生长影响及配套取秧效果【结果】1)低播量下不同播种方式对秧苗成苗率的影响不大。2)降低播种量提高秧苗生长一致性,且穴播和条播秧苗生长一致性好于撒播。3)与撒播相比,精量穴播和条播能够在低播量下提高秧苗根系盘结力和成毯性,中浙优1号和甬优1540根系盘结力比撒播平均高75.4%和81.0%,播量每穴3粒时即能有效成毯,穴播和条播差异不大。4)精量穴播和条播能够显著降低低播量下机插漏秧率,中浙优1号和甬优1540机插漏秧率平均分别比撒播低76.3%和74.6%,穴播和条播下,两个品种每穴播量3粒的漏秧率均在1%以下,与撒播相比降幅在10个百分点以上。5)精量穴播和条播机插取秧苗数均匀度比撒播要好,两个品种预期取秧2~5苗(5粒)、1~3苗(3粒)和1~2苗(2粒)比例均达80%以上,中浙优1号和甬优1540机插苗数均匀度平均比撒播高121.2%和67.0%,其中,穴播机插取秧苗数均匀度及预期取秧苗数比例高于条播。【结论】精量穴播和条播可以解决目前杂交稻机插用种量大、漏秧率高和机插取秧苗数均匀度差的问题。     

麦/油-稻轮作下秸秆还田与氮肥管理对直播杂交稻氮素利用特征的影响

【目的】探明秸秆还田和氮肥管理对麦/油后直播杂交稻氮素积累、转运、氮肥利用效率及籽粒产量的影响。【方法】选用优质三系杂交稻宜香优2115,采用二因素裂区设计,麦、油茬田同步开展试验,处理完全一致。主区为麦/油秸秆全量翻埋还田(M₁)和秸秆不还田(对照,M₀),副区设4个氮肥管理,即不施氮对照(N₀)、m_基肥∶m_分蘖肥∶m_促花肥∶m_保花肥比例分别为1∶0∶0∶0(N₁)、3∶3∶2∶2(N₂)、2∶2∶3∶3(N₃),测定了直播杂交稻主要生育时期各器官的氮素积累量及籽粒产量。【结果】结果表明,两种轮作方式下,氮肥管理对直播杂交稻主要生育时期的氮素积累、齐穗后茎鞘、叶片的氮素转运及稻株氮素利用效率均存在显著或极显著的调控效应。秸秆还田显著提高麦/油茬杂交稻中后期的氮素积累量、茎鞘和叶片的氮素转运量以及氮肥利用效率,其中,氮肥农学利用率、氮肥偏生产力和氮肥表观利用率较秸秆不还田分别提高了34.96%/28.76%、2.52%/2.61%和31.91%/22.30%。同时,油菜秸秆还田下直播杂交稻各生育时期氮素积累和产量较麦秆还田表现更好,籽粒产量提高481 kg/hm²(5.22%)。M₁N₂处理、M₀N₃处理下,直播杂交稻各阶段的氮素积累速率明显加大,促进结实期茎鞘和叶片的氮素向穗部转运,成熟期稻株氮素积累量优势明显且有较高的氮素利用效率(麦/油茬稻氮肥农学利用率、偏生产力和表观利用率分别达17.87 kg∙kg^-1/17.85 kg∙kg^-1、67.27 kg∙kg^-1/71.28 kg∙kg^-1、74.93%/75.05%),最终实现高产。【结论】在麦/油-稻轮作下秸秆全量还田,配合N₂氮肥管理,可有效提高直播杂交稻氮素吸收、利用效率,增加籽粒产量,尤以油菜秸杆还田的效果更好。