Exploring the impact of high density planting system and deficit irrigation in cotton(Gossypium hirsutum L.):a comprehensive review

Lessons learned from past experiences push for an alternate way of crop production.In India,adopting high density planting system(HDPS)to boost cotton yield is becoming a growing trend.HDPS has recently been considered a replacement for the current Indian production system.It is also suitable for mechanical harvesting,which reducing labour costs,increasing input use efficiency,timely harvesting timely,maintaining cotton quality,and offering the potential to increase productivity and profitability.This technology has become widespread in globally cotton growing regions.Water management is critical for the success of high density cotton planting.Due to the problem of freshwater availability,more crops should be produced per drop of water.In the high-density planting system,optimum water application is essential to control excessive vegetative growth and improve the translocation of photoassimilates to reproductive organs.Deficit irrigation is a tool to save water without compromising yield.At the same time,it consumes less water than the normal evapotranspiration of crops.This review comprehensively documents the importance of growing cotton under a high-density planting system with deficit irrigation.Based on the current research and combined with cotton production reality,this review discusses the application and future development of deficit irrigation,which may provide theoretical guidance for the sustainable advancement of cotton planting systems.

Effects of Planting Density on Yield and Mechanical Harvesting Loss Rate of Brassica napus L.

[Objective] This study aimed to explore agronomical measures to reduce the mechanical harvesting loss of rapeseed. [Method] Two rapeseed cultivars, Ningza 19 and Ningza 21, with certain pod-cracking resistance, were employed in field experiments. The two-factor split plot design and randomized complete block design were adopted. The rapeseed seeds were directly sowed with four different seeding rates （1.50, 2.25, 3.00 and 3.75 kg/hm2）. A total of four treatments were designed （112 500, 225 000, 337 500 and 450 000 plants/hm2）. After ripe, the rapeseed was harvested with harvester. Then the yield and harvesting loss rate were determined. [Result] When the planting density ranged from 112 500 to 450 000 plants/hm2, the mechanical harvesting loss rate was decreased with the increase of planting density （Ningza 19, 7.54%-4.01%; Ningza 21, 7.19%-3.81%）. The total loss rates were all below 5% for the high plant densities, 337 500 and 450 000 plants/hm2. High planting density had certain regulating effects on plant type of rapeseed, including reducing plant height, reducing biomass per plant, reducing branch pod numbers per plant, weakening crossing and tangling among stems and improving ripening uniformity of pods. All the changes above were all conducive to reducing mechanical harvesting loss. In addition, the test results showed after the pods grew to maturity, especially when pods were yellow and the moisture content in grains was reduced to 11%, the mechanical harvesting loss only accounted for about 1% of the total field loss. In addition, the shattering loss, caused by mild col- lision, represented more than 90%, and the cleaning loss, occurred during the threshing and cleaning process, represented 4%-8% of the total field loss. The un- harvesting loss accounted for approximately 1% of the total loss. The shattering loss is closely related to cultivar characteristics, planting density, production level and other agronomic factors. The cleaning loss is determined by properties of harvesting machines. The unharvesting loss depends on mechanical properties ad skills of workers or farmers who drive harvesting machines. [Conclusion] In order to reduce mechanical harvesting loss, the rapeseed production should be improved from the perspectives of agricultural machinery and agronomic measures.

Comparison of yield traits in rice among three mechanized planting methods in a rice-wheat rotation system

Understanding the differences in yield traits of rice among pothole seedling of mechanical transplanting （PSMT）, carpet seedling of mechanical transplanting （CSMT） and mechanical direct seeding （MDS） is of great importance not only for rice scientists but also for rice farmers to develop a high-yield production system under mechanical conditions in a rice-wheat rotation system. However, such traits are yet to be studied among rice varieties ofjaponica-indica hybrid rice （JIHR）,japonica conventional rice （JCR） and indica hybrid rice （IHR）. Field experiments were conducted in 2014 and 2015, where six cultivars of the three rice types JIHR, JCR and IHR were grown individually with PSMT, CSMT and MDS methods, under respective managements for each method to achieve the maximum attainable yield. Results showed that （i） the PSMT significantly increased grain yield of JIHR by 22.0 and 7.1%, of JCR by 15.6 and 3.7% and of I HR by 22.5 and 7.4%, compared to MDS and CSMT on average across the two years, respectively. The highest yield was produced by the combination of JIHR and PSMT; （ii） high yield under PSMT was mainly attributed to large sink capacity and high-efficient dry matter accumulation. With sufficient panicles per hectare, the increase of spikelet number per panicle, especially the increase in spikelet number of the secondary rachis-branches was determined to be the optimal approach for developing a large sink capacity for rice under PSMT. The optimal tillers development, large leaf area index at heading stage, and high leaf area duration, crop growth rate and net assimilation rate during grain-filling phase could be the cause of sufficient dry matter accumulation for rice under PSMT; （iii） moreover, the PSMT favored plant growth as well as enriched the stems plus sheaths during grain-filling phase, as compared with CSMT and MDS. These results suggest that PSMT may be an alternative approach to increasing grain yield in a rice-wheat rotation system in the lower reaches of the Yangtze River in China.

Reducing environmental risk of nitrogen by popularizing mechanically dense transplanting for rice production in China

The high nitrogen(N)application rates typically used in Chinese cropping systems have led to diminishing returns for yields and have also imposed substantial environmental costs.Here,we estimate that the annual N loss from rice production in China reached approximately 2.6×109 kg from 2011 to 2015,and we demonstrate that adoption of the mechanically dense transplanting technique by producers is an effective method to reduce N loss from rice cropping systems without suffering a yield penalty.

Temperature and solar radiation utilization of rice for yield formation with different mechanized planting methods in the lower reaches of the Yangtze River,China

Several studies have demonstrated the effect of planting methods on rice yield, but information on the climate resources is limited. This study aims to reveal the effects of planting methods on climate resources associated with rice yield in a rice-wheat rotation system in the lower reaches of the Yangtze River, China. Field experiments were conducted in 2014 and 2015 with two japonica, two indica hybrid, and two japonica-indica hybrid varieties grown under three mechanized planting methods： carpet seedling of mechanical transplanting（CT）, mechanical direct seeding（DS）, and pot-hole seedling of mechanical transplanting（PT）. The rice yield and total dry matter under PT were greater than those under CT and DS methods. Besides, the entire growth duration and daily production showed significant positive relations with rice yield. Compared with CT and DS, the effective accumulated temperature and cumulative solar radiation of rice under PT were higher in phenological phases. In addition, the dry matter/effective accumulated temperature and solar energy utilization of rice under CT and DS were higher during vegetative phase and lower during reproductive and grain filling phases in contrast to PT. The mean daily temperature and mean daily solar radiation in the entire growth duration showed significant positive correlation with rice yield, total dry matter, and harvest index. This study demonstrated that when the mean daily temperature is 〈25.1°C in vegetative phase and 〉20.1°C in grain filling phase, rice yield could be increased by selecting mechanized planting methods. Most varieties under PT method exhibited high yield and climate resources use efficiency compared with CT and DS. In conclusion, the PT method could be a better cultivation measure for high rice yield, accompanied with high temperature and solar radiation use efficiency in a rice-wheat rotation system in the lower reaches of the Yangtze River, China.

Large-ridge Mechanized Planting Technology of Potato in Hailar District of Hulunbeier City

The mechanized large-ridge production technology of potato was summarized,including preparation before sowing,deep tillage and land preparation,deep application of chemical fertilizer,sowing,intertillage,disease and pest control,harvesting and other related contents.The comparative experimental study of large ridge and small ridge modes focused on the effects of ridge spacing on soil bulk density,temperature,water retention,crop growth and yield.The technology has the advantages of time saving,labor saving,seed saving,and fertilizer saving.It can significantly improve production efficiency,and is a high-yield and high-efficiency planting mode that increases potato yield.This model can increase yield by 370 kg/hm 2 and improve income by 160 yuan/hm 2.The results of this study have greatly promoted the promotion and application of mechanized largo-ridge potato planting technology.

Study on a Bowl-based Mechanism for Transplanting Potted Strawberry Seedlings

To improve the efficiency of fetching and transplanting seedlings for the mechanization of strawberry planting,an integrated transplanting mechanism was designed with protruding,fetching and planting performance to achieve rapid fetching and pushing bowl movements.According to the working principle of the slewing mechanism,a kinematics model and the optimization goal were established,respectively.Based on visual auxiliary analysis software,optimal parameters were obtained.A three-dimensional model was established to obtain a simulation trajectory by means of a virtual simulation design analysis.Three-dimensional printing technology was used to manufacture the test prototype,and the actual working trajectories of the test prototype were extracted using high-speed photography technology,which verified the consistency of the actual trajectory with the theoretical and simulated trajectories.A prototype transplanting experiment was performed with the success rate of seedling extraction of 91.2%and excellent planting rate of 82.8%,which met the requirements for integrated strawberry harvesting,planting and transplanting.The experimental results verified the correctness and feasibility of the design of integrated transplanting mechanism.

草莓移栽机控制系统设计与试验

针对草莓高起垄定向移栽农艺要求,设计一种机械打穴、人工识别草莓苗弓背方向后定向穴栽的移栽机。基于可编程控制器(PLC)设计整机控制系统,包括移栽机定速行走控制系统、前轮转向控制系统、打穴控制系统等任务模块。整机采用直流无刷电机作为底盘的驱动元件,根据电机自带编码器的输出值进行行走速度、栽植株距和打穴频率的协调控制,采用步进电机作为打穴机构的驱动元件,由接近开关对打穴机构进行定位,通过二者配合完成打穴过程,在人机协同作业下,完成草莓苗移栽。试验结果表明:当单行移栽效率为15株/min,株距为150 mm、200 mm、250 mm时,株距合格率、孔深合格率、孔径合格率均在95%以上,其变异系数均小于5%,打穴成功率均大于95%,符合移栽机行业标准,打穴移栽效果满足农艺要求。

土壤微塑料影响植物生长的因素与机制研究进展

土壤中的微塑料可通过多种方式影响植物生长,并且其在植物体内积累会最终通过食物链进入人体,厘清微塑料对植物生长的影响及机制,有助于系统掌握其在土壤-植物体系中的环境行为。微塑料的赋存状态和理化特征均可影响其对植物的作用效果,本文从粒径、形状、浓度、种类、塑料添加剂和老化程度等方面,梳理了土壤微塑料影响植物生长的主要因素及作用机制,并对未来研究的重点内容提出展望,以期为进一步明晰微塑料对土壤生态系统的影响提供参考。

基于植物功能群的生态系统服务形成与维持机制研究

生态系统可以从“结构-功能-服务”3个层次来理解,其中服务是人类的主观感受或效用。维持高质量的生态系统服务还需从生态系统的自然属性入手。结构和功能是生态系统服务形成和维持的内在机制,而植物是生态系统结构和功能的核心驱动力。植物功能群具有特定功能的植物组合,其中优势植物功能群控制着生态系统的结构和功能。生态系统服务的概念、分类与植物功能群密切相关,植物功能群是生态系统与生态系统服务间更直接的桥梁。建立生态系统服务与植物功能群间的联系,使相关研究有更明确的指向,在深化理论研究的同时使研究成果更容易落地。生态系统服务的形成、维持机制与植物功能群的内在联系主要体现在4个主要方面:(1)植物功能群的内在适应性特征和外在效应是生态系统服务形成的基础;(2)植物功能群的多功能特性为生态系统服务协同提供了可能;(3)植物功能群间替代和互补效应可以提升生态系统服务质量和稳定性;(4)植物功能群能够提供基于自然的生态系统服务修复问题解决方案。

基于改进DeepLabv3+的光伏电站道路识别方法

针对移动清洁机器人在光伏电站作业时需要精确快速识别道路的问题,提出一种改进的DeepLabv3+目标识别模型对光伏电站道路进行识别.首先,将原DeepLabv3+模型的主干网络替换为优化的MobileNetv2网络以降低模型复杂度;其次,采用异感受野融合和空洞深度可分离卷积结合的策略改进空洞空间金字塔池化(ASPP)结构,提高ASPP的信息利用率和模型训练效率;最后,引入注意力机制,提升模型识别精度.结果表明,改进后模型的平均像素准确率为98.06%,平均交并比为95.92%,相比于DeepLabv3+基础模型分别提高了1.79个百分点、2.44个百分点,且高于SegNet、UNet模型.同时,改进后的模型参数量小,实时性好,能够更好地实现光伏电站移动清洁机器人的道路识别.

盐碱胁迫对植物的影响及抗性机制研究进展

盐碱胁迫是仅次于干旱胁迫抑制植物生长发育的主要非生物胁迫之一,不仅影响植物的生长发育,而且对农业生产和生态环境造成严重威胁。研究植物的耐盐碱机制,对耐盐碱作物选育及盐碱地的开发利用具有重要的现实意义。结合近年来国内外的相关研究总结性阐述了盐碱胁迫对植物代谢的伤害(包括离子伤害、膜系统伤害、诱导渗透伤害等)机制,并从膜系统保护以及诱导基因表达方面综述了植物对盐碱胁迫的缓解机制,进而提出外源物质的导入、生物技术手段、耐盐碱品种培育是解决植物抗盐碱的主要手段。最后就植物适应盐碱胁迫方面的研究进行了展望,指出了当前研究者需要解决的问题和突破口,旨在为提高植物耐盐碱能力、增加作物产量提供一定的理论依据。

植物种子衰老机制研究进展

种子在贮藏过程中的衰老即可直接导致建苗迟缓,幼苗畸形,最终影响作物产量,也可以导致商业贮藏中粮食品质的下降,还会影响种质资源库的更新周期和自然环境野生植物的生存。因此,深入认识种子衰老的生物学过程,对于农业生产和种质资源安全保存具有重要意义。本文系统综述了植物种子衰老生物学特征,从基因到表型,分析造成种子衰老的内外因,包括种子衰老过程中解剖结构、亚细胞结构、生理生化和分子生物学原因,以及环境等外界诱导因素,构建出一个完整种子衰老网络图。以期为种子衰老机理、种子活力修复和种质资源保存等研究提供基础理论参考。

丘陵山地不同种植模式下甘蔗主栽品种生产的潜力

【目的】以丘陵山地不同种植模式甘蔗主栽品种生产潜力为研究对象,探索品种和机械适应关系,筛选宜机化(适宜机械作业)种植的甘蔗品种并明确其主要特征,为推动丘陵山地蔗区全程机械化提供理论支撑。【方法】选择云南丘陵山地2种不同生态类型蔗区,对桂柳05-136、云蔗05-49、云蔗05-51和云蔗08-1609 4个主栽品种进行全程机械化和全程人工2种种植模式下生产潜力研究。【结果】甘蔗产量和蔗糖分受品种和种植模式影响,其中产量影响显著,机械化种植模式下,云蔗08-1609产量显著高于人工种植模式(P<0.01),云蔗05-51表现相反(P<0.01);机械化种植模式下,云蔗08-1609蔗糖分略高于人工种植(P>0.05),桂柳05-136和云蔗05-49略降低(P>0.05)。甘蔗下种量和出苗率同时受品种特性和种植模式影响,机械化种植模式下下种量普遍高于人工种植,而出苗率普遍低于人工种植模式;云蔗05-51机械化种植条件下出苗率显著降低(P<0.05),云蔗08-1609出苗率相对较稳定(P>0.05)。甘蔗主要农艺性状同时受品种和种植模式影响,机械化种植模式下,云蔗08-1609有效茎显著高于人工种植模式(P<0.05);工艺品质性状主要受品种影响。云蔗08-1609在甘蔗机械种植条件下生长潜力更高,表现为产量和有效茎显著高于人工种植,甘蔗蔗糖分略高;云蔗05-51在人工种植模式条件下生长潜力更高,表现为人工种植模式下的产量更高。【结论】不同甘蔗品种对机械种植的适应程度不同,存在宜机化种植和宜人工种植甘蔗品种,在推进机械化种植模式过程中应充分考虑品种的适应性;总之,宜机化种植甘蔗品种应具备在机械化种植模式下的甘蔗产量更高和有效茎更多,且蔗糖分受种植模式影响较小甚至略高于人工种植模式的特征。

植物纤维增强混凝土力学性能试验研究

以剑麻纤维、黄麻纤维和竹纤维为增强体,研究了植物纤维对混凝土的抗压、抗折等力学性能的增强效果,以及植物纤维的长度、掺入量和纤维分布对增强效果的影响,并与聚丙烯纤维增强效果进行对比分析。试验证明:植物纤维对混凝土抗压强度的影响可忽略不计,但对混凝土抗折强度产生重要影响。剑麻纤维(长度20 mm,体积分数1.5%)、竹纤维(长度10 mm,体积分数1.0%)和黄麻纤维(长度10 mm,体积分数1.5%)增强效果均较好,竹纤维增强效果优于其他两种植物纤维。植物纤维混掺增强效果优于单一植物纤维增强效果,总体积分数1.5%的“剑麻纤维—黄麻纤维—竹纤维”混掺增强效果最好。

天然植物多糖的动物免疫调节功能研究进展

多糖是生命活动中必不可少的大分子,具有抗氧化、调节免疫等生物学活性.由于商品饲料近年来全面禁止添加抗生素,天然植物多糖以其生物功效明显、来源广泛、生物可降解性高、毒副作用小等优势,成为当下研究热点.天然植物多糖对畜禽免疫系统的调节作用主要包括调节肠道免疫功能以及通过模式识别受体来调节机体免疫.调节肠道免疫的方式主要有调节肠道菌群、修复肠道屏障、改善肠道微生物发酵等三种.通过模式识别受体调节机体免疫主要通过促进畜禽机体免疫器官的生长、激活免疫细胞、调控免疫应答等途径实现.对天然植物多糖上述功效及具体作用机理进行综述,旨在为其高效开发利用提供参考.

不同种植密度和行距配置对香蕉产量及品质的影响

为确定香蕉适宜机械化操作的种植密度和行距配置,采用裂区试验设计,以种植密度(P,P1:2190株/hm^(2);P2:2340株/hm^(2);P3:2520株/hm^(2))为主区,行距(R,R1:宽行5.10 m+窄行1.00 m;R2:宽行4.80 m+窄行1.30 m;R3:宽行4.50 m+窄行1.60 m)为裂区,探讨不同种植密度和行距配置对香蕉农艺性状、产量及品质的影响。结果表明:R能显著影响香蕉株高和茎围,P和R对香蕉单产、总产量均有显著影响,P1、P2香蕉单产较P3分别显著提高10.29%、10.88%,P2总产量较P1显著提高6.62%;R3单产、总产量最高,R1单产、总产量最低。分析产量构成可知,R3能提高香蕉商品蕉采收率;P1、P2单果质量较P3显著提高,R3单果质量较R1、R2分别显著提高21.23%、4.44%。P1果指长较P3显著提高,R2、R3间果指长、果指围显著高于R1。P和R对果实可溶性固形物含量均无显著影响。P3可滴定酸含量较P1、P2显著提高,P1、P2的维生素C含量分别较P3显著提高19.38%、15.78%;R3较R1显著提高维生素C含量8.77%。综上所述,宝岛蕉品种种植密度为2340株/hm^(2),宽行4.50 m、窄行1.60 m时,香蕉农艺性状、产量、商品蕉采收率、单果质量、可溶性固形物及维生素C含量最高。

人为干扰对黄河湿地植物群落的影响及其机制

为了分析人为干扰类型对黄河湿地植物群落的影响差异及相关作用机制,在进行大量实地调查后,选择郑州段3个分别受农业种植、水库修建、建筑施工干扰下的湿地为对象,在对植物群落与相关环境因子指标进行测定后,结合人类压力指标评价体系进行冗余分析。结果表明:研究区湿地植物群落整体表现出明显的退化趋势,维持湿地生产力的内在功能降低;对于不同人为干扰类型下的样地,受到人为干扰的严重程度从大到小依次为建筑施工类干扰、农业种植类干扰、水库修建类干扰;随着人为干扰严重程度的加剧,不同湿地植物群落相似性系数依次下降,鸟类栖息地湿地和太平庄北湿地的物种丰富度指数较桃花峪湿地相比下降程度分别为15.98%和37.05%,整体湿地植物群落构建逐渐趋于简单化;在引起湿地退化的诸多因素中,土壤中铵态氮含量改变对物种多样性指数与物种均匀度指数呈显著负相关,是湿地植物退化的主要原因之一。

辣椒漂盘苗机械化移栽适应性研究

为了探索辣椒漂盘苗对机械化移栽的适应性,以贵州某辣椒基地所育适栽期辣椒漂盘苗和2ZB-2旱地吊杯鸭嘴式移栽机为测试对象,完成了辣椒苗形态特征参数测量、落苗基质损失及田间机械栽植的试验研究。结果表明:从辣椒苗的苗高、叶面展幅、基质情况来看,所育漂盘苗基质饱满,且适于膜上移栽常用的鸭嘴式栽植器;漂盘苗基质含水率在56.4%~63.5%时,利于机械移栽的基质保持;田间机械移栽的栽植深度合格率、漏栽率、伤苗率分别为76.7%、2.4%、3.2%,满足指标要求;直立度合格率为88.7%,低于93%的指标下限。总体来说,辣椒漂盘苗与移栽机适应性较好,基本能达到贵州辣椒机械化栽植作业要求。

香芹酚对肠炎沙门氏菌的抗菌活性及机制研究

为探讨香芹酚对肠炎沙门氏菌的抗菌活性及抗菌机制,试验以天然植物精油香芹酚为研究对象,以肠炎沙门氏菌作为指示菌,通过测定肠炎沙门氏菌的抑菌圈直径、最小抑菌浓度(MIC)、最小杀菌浓度(MBC)和生长情况以评价香芹酚的抗菌活性;研究不同浓度香芹酚对肠炎沙门氏菌菌液电导率、胞外蛋白质和核酸浓度、碱性磷酸酶(AKP)活性及细菌结构变化的影响。结果表明:香芹酚对肠炎沙门氏菌的抑菌圈直径、MIC、MBC分别为(22.5±2.6)mm、0.125μg/mL、0.25μg/mL,肠炎沙门氏菌在1 MIC和2 MIC香芹酚作用下生长受到了明显抑制;随着香芹酚浓度增大,菌液电导率呈现增长的趋势;培养至第3,6小时时,胞外蛋白质和核酸浓度随香芹酚浓度升高显著升高(P<0.05);培养至第6小时时,AKP活性随香芹酚浓度升高显著升高(P<0.05);0.5MIC~2MIC香芹酚能够破坏菌体结构,使菌体出现形态改变、皱缩、溶解等结构变化。说明香芹酚可以通过破坏肠炎沙门氏菌菌体细胞壁或细胞膜通透性及完整性,致使菌体内容物泄露,对肠炎沙门氏菌表现出良好的抗菌活性。