昆虫的气味受体（Odorant receprot，OR）是它们探测和识别与其生存密切相关的外部化学线索的关键。昆虫识别配体的特异性受体与一个广泛存在的气味受体共受体（Odorant receptor coreceptor，Orco）构成了异聚体复合体。本研究运用CRISPR/Cas9基因敲除技术对我国重大入侵害虫草地贪夜蛾的Orco基因进行了敲除，并揭示了该基因在气味受体调控的嗅觉行为中的重要作用。触角电位结果表明，Orco基因敲除之后，雌雄成虫对8种测试的植物挥发物和两种性信息素的电生理反应均丧失。然而，Orco基因对雌雄成虫交配行为的影响却存在明显的差异：雄虫Orco突变体的交配行为完全被干扰而雌虫Orco突变体的交配行为却不受影响。产卵实验结果表明，Orco突变体雌虫的产卵量比野生型雌虫的产卵量减少了24.1%。总之，这些结果表明了Orco是一个干扰草地贪夜蛾正常行为的优良靶标，并为害虫的防治提供了一种可行的方法。

陆地棉是世界上最重要的纤维作物。株高作为植物株型的重要组成部分，影响着作物的种植模式、产量和经济系数。前期研究中，我们分离并鉴定了一个棉花HD-ZIP基因（GhHB12），该基因调控棉花的非生物和生物胁迫应答反应和生长发育过程。在本研究中，我们证明GhHB12基因受生长素诱导表达，过表达GhHB12基因能激活HY5、ATH1和HAT4基因的表达，抑制生长素的时空分布、极性运输和信号传导，并改变细胞壁扩张相关基因的表达，最终抑制棉花株高。这些结果表明，GhHB12可以通过影响生长素的信号传导和细胞壁的扩展来调节棉花株高。

芒果在低温贮藏下常发生冷害(CI)。因此，迫切需要采用先进技术来解决芒果低温胁迫的伤害，提升产品的价值。本文研究了0.1 (MT1)和0.2 mmol L^-1 (MT2)褪黑素溶液浸泡30分钟处理对‘凯特’芒果在低温藏期间CI、脯氨酸代谢和相关基因表达的影响。结果表明：与对照相比，MT1浓度褪黑素处理显著降低了芒果果实冷藏期间的CI发展，增加了脯氨酸含量；这些变化伴随着脯氨酸生物合成关键酶活性及其编码基因表达的增加，包括吡啶-5-羧酸合成酶(P5CS)、吡啶-5-羧酸还原酶(P5CR)、鸟氨酸D -氨基转移酶(OAT)、P5CS2、P5CR2和OAT3。同时，经MT1处理芒果的脯氨酸脱氢酶(PDH)活性和PDH3表达量低于对照。因此，褪黑素处理通过调控脯氨酸代谢导致脯氨酸的累积，进而有助于增强‘凯特’芒果果实的抗冷性。

在获得高产的同时改善土壤质量是农业生产的主要挑战。小麦（Triticum aestivum L.）–玉米（Zea mays L.）轮作（W–M）是黄淮海平原的主要种植模式，对保障中国粮食安全具有重要意义。然而，由于长期、集中、连续栽培，W–M轮作系统土壤质量正在退化。我们推测在W–M轮作系统中引入豆科作物可能是改善土壤质量的有效途径，本研究旨在验证这一假设，并探索小麦–花生（Arachis hypogaea L.）轮作（W–P）和小麦轮作玉米/花生间作（W–M/P）的高效种植系统，以实现黄淮海平原农业的高效生产。研究以传统的W–M轮作为对照，基于3年定位试验，系统研究了作物产量、净收益、土壤微生物和土壤碳库特征。结果表明：与W–M相比，W–P和W–M/P处理显著提高了小麦产量（分别提升382.5–579.0和179.8–513.1 kg ha^–1）和净收益（分别提高58.2和70.4%）；在0 ~20 cm土层，W–M/P和W–M土壤有机碳储量比W–P分别增加了25.46–31.03%和14.47–27.64%；W–M/P改善了土壤活性碳组分，其中，20–40 cm土层的潜在可矿化碳、10–40 cm土层的微生物量碳和10–20 cm土层的可溶性有机碳的敏感指数分别达31.5%、96.5–157.2%和17.8%；细菌群落组成和功能随土壤深度和种植系统的不同而变化，W–M/P和W–M在0–20和20–40 cm土层分别具有相似的细菌群落组成和功能；与W–P相比，W–M的10–20 cm土层和W–M/P的0–20 cm土层具有较高的移动元件（contains mobile elements）和耐胁迫（stress tolerant）功能基因丰度、较低的潜在致病（potentially pathogenic）基因丰度；土壤有机碳和微生物量碳是影响土壤细菌群落的主要因素，其含量与Sphingomonadales和Gemmatimonadales正相关、与Blastocatellales负相关；作物有机物料输入是影响土壤有机碳和微生物群落变化的主要因素，并反馈作用于作物产量。综上，与传统的W–M系统相比，W–M/P系统可提高作物产量、净收益，改善土壤有机碳库，在设计高产种植系统时应考虑植物-土壤-微生物的相互作用。

本研究以华北玉麦轮作农田石灰性土壤为研究对象，针对玉米和小麦季的两次施肥事件，采用¹⁵N气体通量法（¹⁵NGF）对田间原位土壤N₂通量进行为期一周的观测。施用肥料为¹⁵N标记尿素（丰度为99 atom％），施用量为130（玉米季）和150（小麦季）kg N ha^–1；并于施肥后的第一、三和五天（缩写DAF 1、DAF 3和DAF 5）进行模拟灌水，控制灌水后土壤湿度达~60% WFPS。结果显示：当罩箱时间为2、4和6 h时，土壤N₂通量的检测限分别为163–1565、81–485和54–281 μg N m^–2 h^–1。土壤N₂通量为159–2943（平均：811）μg N m^–2 h^–1，98.3%的通量数据高于其检测限（即120个观测数据中仅2个达不到通量检测限）。灌溉时间显著影响玉米季观测期内的土壤N₂平均通量，DAF 3处理较DAF 1和DAF 5处理高约80%（p<0.01）；而在小麦季，不同灌溉时间的N₂通量无差异。而且，玉米季观测期内的N₂通量和氧化亚氮（N₂O）与N₂产物比（N₂O/(N₂O+N₂)）均较小麦季高约65%和11倍（p<0.01）。该差异主要归因于玉米季观测期内更高的土壤湿度、温度和氮底物的有效性，利用反硝化贡献N2排放和N₂O/（N₂O+N2）比值。该研究表明¹⁵NGF方法可应用于原位定量集约化石灰性农田土壤的N₂通量。

为明确不同生育时期受灾对棉花恢复生长及产量的影响，本研究于2018-2019年，以鲁棉研24号为供试材料，采用自制工具拍打法从棉花五叶期至吐絮期每隔约15天（同一地块只进行一次损害处理）进行4种程度（0%、30%、60%和90%），共计六次（Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ）的雹灾模拟试验，获取受灾后植株叶面积指数、光合势、干物质积累与分配、产量及吐絮铃空间分布图。研究结果表明，棉花籽棉产量随受灾程度的增加而下降，降幅随受灾时期的推迟而增大，其中在花后（第Ⅳ、Ⅴ、Ⅵ时期），30%、60%和90%受灾程度的产量比0%受灾程度分别减少9%-17%、22%-37%和48%-71%。这是由于棉花受雹灾损害后植株叶面积指数和光合势下降，导致干物质积累量减少，但由于棉花的无限生长习性，花前（第Ⅰ、Ⅱ、Ⅲ时期）受灾后营养器官产生较强的补偿能力进而促使蕾铃发育，仅植株中上部及外围果节的吐絮铃受到影响，造成较少的产量损失；花后受灾后营养器官补偿能力下降、恢复时间短，不足以促进新生铃发育、成熟，导致有效果枝数及各果节吐絮铃数下降，造成较大的产量损失。因此，花前受灾后补救措施应以促蕾铃发育为主，促叶片发育为辅；花后受灾后补救应以保铃、促叶片发育为主。本文从灾后植株叶面积指数、光合势、地上生物量积累与分配等方面研究棉花受雹灾损害后的恢复生长及其对最终产量的影响，该研究结果可为减灾、制定灾后管理方案及产量预测提供理论依据。

小麦抗旱相关基因TaPYL4的功能分析及标记开发

本研究通过抗原性分析发现，2020年至2021年在野鸟或家禽中分离的一些H5N6、H5N8和H5N1病毒与我国大规模应用的H5疫苗种毒株(H5-Re11株和H5-Re12株)的抗原性存在较大差异，部分2021年分离的H7N9病毒也与我国使用的H7-Re3株疫苗毒株存在抗原性差异。为保持疫苗株与监测毒株之间良好的抗原匹配性，本研究利用反向遗传学操作技术，构建出针对抗原变异毒株的3株重组疫苗种毒（H5-Re13、H5-Re14和H7-Re4），用于疫苗的更新。其中，H5-Re13疫苗株的HA和NA基因来自于2.3.4.4h分支的H5N6病毒（DK/FJ/S1424/20），H5-Re14疫苗株的HA和NA基因来自于2.3.4.4b分支的H5N8病毒（WS/SX/4-1/20），H7-Re4疫苗株的HA和NA基因来自于2021年分离的H7N9病毒（CK/YN/SD024/21）。进一步使用上述3株重组病毒制备新型H5+H7三价灭活疫苗，进行鸡、鸭和鹅的免疫效力研究。结果显示，H5+H7三价灭活疫苗接种鸡、鸭和鹅后均可诱导出良好的HI抗体反应；SPF鸡接种疫苗后3周时，用2020年和2021年分离到的5株不同H5和H7病毒攻击，包括3株2.3.4.4b分支病毒（H5N1、H5N6和H5N8病毒各1株）、1株2.3.4.4h分支的H5N6病毒和1株H7N9病毒，攻毒后所有对照组鸡均出现高滴度的排毒，并在攻毒后4天内全部死亡，而疫苗接种组鸡则完全抵御病毒的感染；接种疫苗的鸭和鹅在攻击2.3.4.4h或2.3.4.4b分支H5病毒后也获得完全免疫保护。本研究结果表明，新型H5+H7三价疫苗具有良好的免疫原性,对于近期监测到的H5N1、H5N6、H5N8和H7N9病毒的攻击可提供完全的免疫保护作用。鉴于不同H5病毒和H7N9病毒对家禽的威胁，本研究建议我国广泛使用该H5+H7三价灭活疫苗，并推荐该疫苗在其他受到H5和H7病毒威胁的国家应用。

深播是包括玉米在内的作物躲避干旱的一种重要策略，候选基因的克隆是进行玉米耐深播分子机理研究的基础工作。本研究中，我们利用包含386份玉米自交系的关联分析群体对10厘米和20厘米播种深度条件下的四个性状进行鉴定。利用50万SNP标记进行关联分析发现了273个耐深播性状显著关联的SNP。对两组不同的处理进行RNA测序分析分别发现1944和2098个差异基因，其中包含281个共同的差异基因。通过比较273个SNP和281个差异基因的位置发现了7个可能与耐深播相关的候选基因，其中GRMZM2G119769编码一个SNF1激酶互作的蛋白。由于GRMZM2G119769在其他植物中的同源基因跟器官伸长、生长素和光响应有关。同时，候选基因关联分析表明GRMZM2G119769基因的自然变异与玉米的中胚轴长度有关。另外，基因表达分析表明GRMZM2G119769在耐深播材料中表达量高。这些研究结果都支持GRMZM2G119769是玉米耐深播性状的候选基因。本研究不但评价了玉米资源的耐深播特性，还鉴定出一些可能对未来玉米耐深播研究有参考价值的候选基因。

二花脸猪、梅山猪和米猪是我国太湖流域优良的地方猪品种，为商品猪的遗传改良做出了巨大贡献。分析这3个猪种的遗传结构和近交水平，对地方猪遗传多样性的保护以及商品猪的持续改良具有重要意义。长纯合片段（Runs of homozygosity，ROH）的长度、数量以及在基因组中的分布模式可以作为评价群体近交水平和物种起源的指标。本研究利用SLAF-seq数据对4个不同品种（二花脸猪、梅山猪、米猪和长白猪）的猪群体进行全基因组ROH 检测，并根据ROH信息计算了各个猪群体的近交系数（F_ROH）。此外，研究还在高频ROH区域筛选与母猪繁殖性状相关的候选基因。在4个猪种的116个个体中共检测到10,568个ROH。PCA分析表明，太湖流域3个猪种的遗传结构与长白猪存在显著差异，而二花脸猪和米猪的遗传结构较为相似。在4个猪群体中，长白猪短ROH（<5 Mb）的频率最高，而梅山猪长ROH（>5 Mb）的频率最高，明显高于二花脸猪和米猪。梅山猪个体ROH覆盖总基因组的长度和ROH总数接近于长白猪，也明显高于二花脸猪和米猪。同时，梅山猪的平均F_ROH最高与长白猪相近，二花脸猪的平均F_ROH最低与米猪相近。以上结果表明梅山猪和长白猪一样表现出较高的近交水平，梅山猪较高的近交水平主要来源于近代的近亲繁殖，而二花脸猪和米猪的近交水平相对较低。此外，大量与母猪繁殖性状相关的候选基因在高频ROH区被鉴定到，这些基因有望作为标记辅助选择(MAS)育种的候选基因。本研究的结果为太湖流域3个猪种的遗传多样性保护、防止近交衰退和遗传改良提供了理论依据。

绒毛膜形成期是昆虫卵子发生的最后阶段，在这一阶段，滤泡细胞通过合成分泌绒毛膜蛋白，转移至发育的卵母细胞表面沉积形成卵壳，为胚胎发育提供保护屏障。目前对绒毛膜基因家族的研究大多集中在模式昆虫，如家蚕和果蝇，在世界性害虫小菜蛾中仍缺少对绒毛膜基因家族的系统鉴定以及其功能分析。因此明确绒毛膜基因家族在小菜蛾基因组上的分布情况及其转录特征，解析绒毛膜基因在小菜蛾卵子发生过程，以及胚胎发育过程中的重要作用，可为小菜蛾的遗传调控提供潜在分子靶标。本研究分析鉴定了小菜蛾绒毛膜基因的数量及染色体定位、分子特征、进化关系及其启动子区的序列特性，基于转录组数据以及qPCR实验，分析了绒毛膜基因在不同龄期和不同组织的表达模式，并基于RNAi揭示了PxCho-1的生殖功能。在小菜蛾中一共鉴定得到15个绒毛膜基因，分为A、B两大类。不同类型绒毛膜基因以成对的方式分布在染色体上。部分绒毛膜基因对，共享一个双向启动子调控区。系统发育分析表明，A、B两类绒毛膜基因具有高度的保守性，并且在对应类别中，小菜蛾绒毛膜基因均具有物种特异性。不同龄期与组织的表达谱与qPCR分析均显示，绒毛膜基因主要在小菜蛾雌成虫中显著高表达，并且在卵黄完全沉积的卵巢内显著高表达，说明绒毛膜基因在小菜蛾雌成虫的生殖发育中具有重要作用，且主要作用于卵子发生后期。抑制PxCho-1基因转录虽然对卵黄沉积没有影响，但会导致卵子变小，孵化率急剧下降，同时导致卵子内卵壳柱状层的排列松弛，以及外卵壳绒毛变短。本研究为探索小菜蛾雌性生殖调控机制奠定了理论基础，有利于筛选潜在的小菜蛾遗传防控分子靶标。

温度和水分是影响水稻产量和品质形成的重要因子，灌浆结实期适度的干旱能够有效的缓解高温胁迫对水稻造成的伤害，但有关其淀粉合成的调控机理尚不清楚。为探明灌浆结实期高温与干旱对水稻淀粉合成的影响及其生理机制，本试验研究了4个不同处理下（对照（CK）、高温（HT）、适度干旱（WS）、高温干旱（HT+WS））常规粳稻淀粉相关酶活性及其基因的表达水平。结果表明高温和干旱对籽粒灌浆的影响主要发生在弱势粒中，并通过调节参与淀粉合成相关酶活性及其主效基因的表达水平，进而影响稻米淀粉的合成。高温和干旱有拮抗作用，适度干旱能够改善高温对稻米品质的影响。

昆虫鱼尼丁受体（RyRs）是邻甲酰氨基苯甲酰胺类和邻苯二甲酰胺类等二酰胺类杀虫剂的靶标。目前，已经有几种二酰胺类杀虫剂在我国果园害虫防治中应用。为了加强二酰胺类杀虫剂作用机制的了解，本文克隆了危害仁果和核果类较为严重的害虫苹小卷叶蛾的RyR（AoRyR）基因cDNA全长。此外，还研究了二酰胺杀虫剂对AoRyR mRNA表达调控的影响。通过本研究获得AoRyR mRNA的开放阅读框(ORF)为15402 bp，可编码5113个氨基酸。氨基酸序列比对结果显示，AoRyR与其他昆虫和哺乳动物RyRs分别具有77-92%和45-47%的一致性。在AoRyR中发现了一个可变剪接位点为互斥外显子(a/b)，其在卵和幼虫中的使用频率高于蛹和成虫。实时荧光定量qPCR显示，AoRyR mRNA在各发育阶段均有表达，特别是在卵、蛹和雄成虫中高表达。3龄幼虫经LC₁₀、LC₂₀和LC₅₀剂量氯虫苯甲酰胺处理后，AoRyR mRNA表达水平明显上调。研究结果为进一步研究苹小卷叶蛾鱼尼丁受体的功能和开发具有抗虫选择性活性的新化合物提供了依据。

试验采用温室水培的方式，以豫麦49（高铵迟钝型）和鲁麦15（高铵敏感型）为材料，设置了5.0 mM NH₄⁺-N（EAC）和NO₃^--N（CON）两个处理，研究了小麦幼苗根系氧化代谢对高铵胁迫的响应机制。结果表明，高铵胁迫下，两个小麦品种根系生长显著降低，其中鲁麦15降低程度高于豫麦49。高铵胁迫增加了两个小麦品种根系单脱氢抗坏血酸还原酶活性和脱氢抗坏血酸还原酶活性，但降低了处理12天后的根系抗坏血酸（ASA）含量和GDP-甘露糖焦磷酸酶（GMPase）活性，其中鲁麦15根系ASA含量和GMPase活性分别降低了62.0和71.4%，豫麦49根系ASA含量和GMPase活性分别降低了38.8和62.2%，说明高铵胁迫提高了ASA再生，但减少了ASA合成。此外，EAC增加了两个小麦品种根系DHA/ASA，活性氧（ROS）含量，丙二醛含量和抗氧化物酶活性。与豫麦49相比，鲁麦15根系中ROS含量和可溶性糖含量相对增加较多，而抗氧化物酶活性增加较少，说明鲁麦15根系氧化代谢紊乱更严重。结果表明，高铵胁迫下，GMPase活性降低导致ASA生物合成的减少可能是ROS过量积累和氧化还原失衡的原因之一，进而抑制小麦幼苗根系生长。与高铵敏感型品种鲁麦15相比，豫麦49具有较强的氧化胁迫保护能力，维持较低水平DHA/ASA，进而保持较好的氧化还原平衡状态，因此更耐高铵。

Available irrigation resources are becoming increasingly scarce in the North China Plain (NCP), and nitrogen-use efficiency of crop production is also relatively low. Thus, it is imperative to improve the water-use efficiency (WUE) and nitrogen fertilizer productivity on the NCP. Here, we conducted a two-year field experiment to explore the effects of different irrigation amounts (S60, 60 mm; S90, 90 mm; S120, 120 mm; S150, 150 mm) and nitrogen application rates (150, 195 and 240 kg ha^–1; denoted as N1, N2 and N3, respectively) under micro-sprinkling with water and nitrogen combined on the grain yield (GY), yield components, leaf area index (LAI), flag leaf chlorophyll content, dry matter accumulation (DM), WUE, and nitrogen partial factor productivity (NPFP). The results indicated that the GY and NPFP increased significantly with increasing irrigation amount, but there was no significant difference between S120 and S150; WUE significantly increased first but then decreased with increasing irrigation and S120 achieved the highest WUE. The increase in nitrogen was beneficial to improving the GY and WUE in S60 and S90, while the excessive nitrogen application (N3) significantly reduced the GY and WUE in S120 and S150 compared with those in the N2 treatment. The NPFP significantly decreased with increasing nitrogen rate under the same irrigation treatments. The synchronous increase in spike number (SN) and 1 000-grain weight (TWG) was the main reason for the large increase in GY by micro-sprinkling with increasing irrigation, and the differences in SN and TGW between S120 and S150 were small. Under S60 and S90, the TGW increased with increasing nitrogen application, which enhanced the GY, while N2 achieved the highest TWG in S120 and S150. At the filling stage, the LAI increased with increasing irrigation, and greater amounts of irrigation significantly increased the chlorophyll content in the flag leaf, which was instrumental in increasing DM after anthesis and increasing the TGW. Micro-sprinkling with increased amounts of irrigation or excessive nitrogen application decreased the WUE mainly due to the increase in total water consumption (ET) and the small increase or decrease in GY. Moreover, the increase in irrigation increased the total nitrogen accumulation or contents (TNC) of plants at maturity and reduced the residual nitrate-nitrogen in the soil (SNC), which was conducive to the increase in NPFP, but there was no significant difference in TNC between S120 and S150. Under the same irrigation treatments, an increase in nitrogen application significantly increased the residual SNC and decreased the NPFP. Overall, micro-sprinkling with 120 mm of irrigation and a total nitrogen application of 195 kg ha–1 can lead to increases in GY, WUE and NPFP on the NCP.

Improving both grain yield and resource use efficiencies simultaneously is a major challenge in rice production. However, few studies have focused on integrating dense planting with delayed and reduced nitrogen application to enhance grain yield, nitrogen use efficiency (NUE) and radiation use efficiency (RUE) in rice (Oryza sativa L.) in the double rice cropping system in South China. A high-yielding indica hybrid rice cultivar (Yliangyou 143) was grown in field experiments in Guangxi, South China, with three cultivation managements: farmers’ practice (FP), dense planting with equal N input and delayed N application (DPEN) and dense planting with reduced N input and delayed N application (DPRN). The grain yields of DPRN reached 10.6 and 9.78 t ha^–1 in the early and late cropping seasons, respectively, which were significantly higher than the corresponding yields of FP by 23.9–29.9%. The grain yields in DPEN and DPRN were comparable. NUE in DPRN reached 65.2–72.9 kg kg^–1, which was 61.2–74.1% higher than that in FP and 24.6–30.2% higher than that in DPEN. RUE in DPRN achieved 1.60–1.80 g MJ^–1, which was 28.6–37.9% higher than that in FP. The productive tiller percentage in DPRN was 7.9–36.2% higher than that in DPEN. Increases in crop growth rate, leaf area duration, N uptake from panicle initiation to heading and enhancement of the apparent transformation ratio of dry weight from stems and leaf sheaths to panicles all contributed to higher grain yield and higher resource use efficiencies in DPRN. Correlation analysis revealed that the agronomic and physiological traits mentioned above were significantly and positively correlated with grain yield. Comparison trials carried out in Guangdong in 2018 and 2019 also showed that DPRN performed better than DPEN. We conclude that DPRN is a feasible approach for simultaneously increasing grain yield, NUE and RUE in the double rice cropping system in South China.

In past 30 years, the wheat yield per unit area of China has increased by 79%. The super-high-yield (SH) cultivation played an important role in improving the wheat photosynthesis and yield. In order to find the ecophysiological mechanism underneath the high photosynthesis of SH cultivation, in situ diurnal changes in the photosynthetic gas exchange and chlorophyll (Chl) a fluorescence of field-grown wheat plants during the grain-filling stage and environmental factors were investigated. During the late grain-filling stage at 24 days after anthesis (DAA), the diurnal changes in net CO₂ assimilation rate were higher under SH treatment than under high-yield (H) treatment. From 8 to 24 DAA, the actual quantum yield of photosystem II (PSII) electron transport in the light-adapted state (ΦPSII) in the flag leaves at noon under SH treatment were significantly higher than those under H treatment. The leaf temperature, soil temperature and soil moisture were better suited for higher rates of leaf photosynthesis under SH treatment than those under H treatment at noon. Such diurnal changes in environmental factors in wheat fields could be one of the mechanisms for the higher biomass and yield under SH cultivation than those under H cultivation. ΦPSII and CO₂ exchange rate in wheat flag leaves under SH and H treatments had a linear correlation which could provide new insight to evaluate the wheat photosynthesis performance under different conditions.

Understanding the characteristics of rice productivity is of great importance for achieving high yield formation.  However, such traits have not yet been studied for different ages of hydroponically grown long-mat rice seedlings (HLMS), which constitutes a new method of seedling cultivation.  Field experiments were conducted to evaluate the effects of seedling age on the growth stage, photosynthesis characteristics, dry matter production, and yield of HLMS.  A conventional japonica rice cultivar (Wuyunjing 24) and an indica hybrid rice cultivar (6 Liangyou 9368) were used as test materials.  The results showed that the whole phase was shortened by 13–15 days for young seedlings (13-day-old) compared with old seedlings (27-day-old), which occurred because the growth process accelerated with the transplantation of young seedlings.  As seedling age increased, the dry matter weight of stems of individual plants and of the population increased at the transplanting stage but decreased at the maturity stage (MS).  Compared with that of 27-day-old seedlings, the average ratio of panicle weight to total plant dry weight of 13-day-old seedlings during a 2-year period increased by 3.71% for Wuyunjing 24 and by 3.78% for 6 Liangyou 9368 at the MS.  Moreover, as seedling age increased, the leaf area index and photosynthetic potential decreased for both cultivars, and the photosynthetic rate markedly decreased at the heading stage (HS).  With the exception of that of Wuyunjing 24 from the jointing stage to the HS in 2014, the crop growth rate was higher for young seedlings than for old seedlings.  Grain yield significantly decreased with seedling age, but no significant difference was detected between the 13- and 20-day-old seedlings for either cultivar.  Therefore, equilibrious and high biological yield formation, vigorous growth in the late stages, and high photosynthetic production capacity are important characteristics and causes of the efficient and sustainable output of photosynthetic systems and for achieving high yield formation in young transplanted seedlings (13–20-day-old).

To optimize the spatial distribution of cotton bolls and to increase the yield, the relationship between yield components and boll spatial distribution was investigated among different Bt (Bacillus thuringensis) cotton varieties.  A five-year field experiment was conducted to reveal the reasons for the differences in lint yield and fiber quality across three Bt cotton varieties with different yield formations from 2013 to 2017.  The lint yield of Jiman 169 (the average yield from 2013–2017 was 42.2 g/plant) was the highest, i.e., 16.3 and 36.9% higher than Lumianyan 21 (L21) and Daizimian 99B (99B), respectively.  And the differences in boll weight among the three cultivars were similar to the lint yield, while the others yield components were not.  So the increase in lint yield was mainly attributed to the enlargement in boll weight.  However, the change in fiber quality was inconsistent with the lint yield, and the quality of L21 was significantly better than that of Jimian 169 (J169) and 99B, which was caused by the diversity of boll spatial distribution.  Compared with 99B, the loose-type J169 had the highest number of large bolls in inner positions; the tight-type L21 had a few large bolls and the highest number of lower and middle bolls.  And approximately 80.72% of the lint yield was concentrated on the inner nodes in Jiman 169, compared with 77.44% of L21 and 66.73% of 99B during the five-year experiment.  Although lint yield was significantly affected by the interannual changes, the lint yield of J169 was the highest and the most stable, as well as its yield components.  These observations demonstrated the increase in lint yield was due to the increase in boll weight, and the large bolls and high fiber quality were attributed to the optimal distribution of bolls within the canopies.

Drip-irrigation is increasingly applied in maize (Zea mays L.) production in sub-humid region.  It is critical to quantify irrigation requirements during different growth stages under diverse climatic conditions.  In this study, the Hybrid-Maize model was calibrated and applied in a sub-humid Heilongjiang Province in Northeast China to estimate irrigation requirements for drip-irrigated maize during different crop physiological development stages and under diverse agro-climatic conditions.  Using dimensionless scales, the whole growing season of maize was divided into diverse development stages from planting to maturity.  Drip-irrigation dates and irrigation amounts in each irrigation event were simulated and summarized in 30-year simulation from 1981 to 2010.  The maize harvest area of Heilongjiang Province was divided into 10 agro-climatic zones  based on growing degree days, arid index, and temperature seasonality.  The simulated results indicated that seasonal irrigation requirements and water stress during different growth stages were highly related to initial soil water content and distribution of seasonal precipitation.  In the experimental site, the average irrigation amounts and times ranged from 48 to 150 mm with initial soil water content decreasing from 100 to 20% of the maximum soil available water.  Additionally, the earliest drip-irrigation event might occur during 3- to 8-leaf stage.  The water stress could occur at any growth stages of maize, even in wet years with abundant total seasonal rainfall but poor distribution.  And over 50% of grain yield loss could be caused by extended water stress during the kernel setting window and grain filling period.  It is estimated that more than 94% of the maize harvested area in Heilongjiang Province needs to be irrigated although the yield increase varied (0 to 109%) in diverse agro-climatic zones.  Consequently, at least 14% of more maize production could be achieved through drip-irrigation systems in Heilongjiang Province compared to rainfed conditions.

Rice planting patterns have changed dramatically over the past several decades in northeast China (NEC) due to the combined influence of global change and agricultural policy.  Except for its great implications for environmental protection and climate change adaption, the spatio-temporal changes of rice cultivation in NEC are not clear.  In this study, we conducted spatio-temporal analyses of NEC’s major rice production region, Heilongjiang Province, by using satellite-derived rice cultivation maps.  We found that the total cultivated area of rice in Heilongjiang Province increased largely from 1993 to 2011 and it expanded spatially to the northern and eastern part of the Sanjiang Plain.  The results also showed that rice cultivation areas experienced a larger increase in the region managed by the Reclamation Management Bureau (RMB) than that managed by the local provincial government.  Rice cultivation changes were closely related with those geographic factors over the investigated periods, represented by the geomorphic (slope), climatic (accumulated temperature), and hydrological (watershed) variables.  These findings provide clear evidence that crop cultivation in NEC has been modified to better cope with the global change.

    Homeobox 1 in Malus×domestica (MdHB-1) is a transcription factor that belongs to homeodomain-leucine zipper I (HD-Zip I) protein subfamily. According to previous reports, MdHB-1 could regulate ethylene synthesis by binding with the MdACO1 promoter, but other functions of MdHB-1 are still unknown. To reveal more clues concerning the characters of the MdHB-1 gene promoter and the functions of MdHB-1, the promoter region of MdHB-1 was cloned from the Royal Gala apple genome and recombined with the β-glucuronidase (GUS) gene in this study. This research was conducted in Nicotiana tabacum and supported by Agrobacterium-mediated transient transformation and bioinformatics analysis. Deletion analysis of the MdHB-1 promoter showed that the GUS gene could be activated by serially deleted promoters, and the activity promoted by 680 nucleotides (nt) was the lowest. The region, which is 266 nt upstream of the initiation code (ATG), was effective for GUS expression. Meanwhile, the activity of the MdHB-1 promoter (-1 057 nt), which was stronger than MdHB-1 promoter (-1 057 to -266 nt) and lack the 5´-untranslated region (5´-UTR), showed that 5´-UTR may have a positive effect on gene transcription. After the sequence analysis, the cis-acting elements that respond to hormones and environmental stresses were identified in the promoter region. The MdHB-1 promoter (1 057 nt) activity in Nicotiana tabacum was positively induced by ethrel and darkness, and it was suppressed by gibberellic acid (GA), whereas abscisic acid (ABA), salicylic acid (SA), wounding, and Pseudomonas syringae pv. tomato (DC3000) treatments revealed a slight auxo-action. These results reveal that the MdHB-1 promoter receive internal or external signals, and MdHB-1 may refer to many biological activities in apple, such as its stress response, development, and ripening.

    This study aimed to provide a theoretical basis for adopting suitable cultivation measures to tackle calcium (Ca) deficiency in citrus leaves. The Newhall navel orange (Citrus sinensis Osbeck) canopy was sprayed with 20.0 mmol L^–1 of Ca(NO₃)₂ during physiological fruit drop period, fruit expanding period, and fruit maturing period on 30, 90, and 210 days after full bloom (DAFB), respectively, and its effects on leaf gas exchange parameters and leaf mineral nutrition and fruit quality were analyzed. The results showed that: (1) The photosynthetic rate (ACO₂) at 9:00 a.m. and 16:00 p.m. of fruit expanding period with 30 and 90 DAFB Ca(NO₃)₂ treatments slightly or significantly improved mainly by decreasing stomatal limitation and nonstomatal limitation, respectively. (2) Compared with control (CK), the Ca concentration in leaves with 30, 90, and 240 DAFB Ca(NO₃)₂ treatments increased by 127.16, 97.53, and 33.33%, respectively, and the leaf magnesium concentration also increased by more than 32.26%. However, Ca(NO₃)₂ canopy spraying on 30 DAFB significantly reduced the leaf potassium concentration, by 22.14% compared with CK. (3) Ca(NO₃)₂ canopy spraying on 30 DAFB decreased the second fruit drop rate by 30.55% and increased the weight per fruit by 25.04%, thus resulting in a significant increase in citrus yield. (4) Spraying Ca(NO₃) on 30 DAFB mainly affected the metabolism of titratable acid (TA) to improve the maturity of citrus fruits. Whilst it improved the external quality and the coloring of citrus fruit significantly. Therefore, Ca(NO₃)₂canopy spraying during physiological fruit drop period has a better influence on the tree character and fruit quality of Newhall navel orange (Citrus sinensis Osbeck).