Dry Matter Partitioning and Harvest Index Differ in Rice Genotypes with Variable Rates of Phosphorus and Zinc Nutrition

Phosphorus （P） and zinc （Zn） deficiencies are the major problems that decrease crop productivity under rice-wheat cropping system. Field experiments were conducted to investigate impacts of P （0, 40, 80 and 120 kg/hm^2） and Zn levels （0, 5, 10 and 15 kg/hm^2） on dry matter （DM） accumulation and partitioning, and harvest index of three rice genotypes ＇fine （Bamati-385） vs. coarse （F-Malakand and Pukhraj）＇ at various growth stages （tiliering, heading and physiological maturity）. The experiments were conducted at farmers＇ field at Batkhela in Northwestern Pakistan for two years in summer 2011 and 2012. The two year pooled data reveled that there were no differences in percent of DM partitioning into leaves and culms with application of different P and Zn levels, and genotypes at tillering. The highest P level （120 kg/hm^2） partitioned more DM into panicles than leaves and culms at heading and physiological maturity stages. The highest Zn level （15 kg/hm^2） accumulated more DM and partitioned more DM into panicles than leaves and culms at heading and physiological maturity stages. The hybrid rice （Pukhraj） produced and partitioned more DM into panicles than F-Malakand and Bamati-385 at heading and physiological maturity stages. Higher DM accumulation and greater amounts of partitioning into panicles at heading and physiological maturity stages was noticed with increase in P and Zn levels, and the increase was significantly higher in the coarse rice genotypes than fine. We concluded that the growing hybrid rice with application of 120 kg/hm^2 P ＋ 15 kg/hm^2 Zn not only increases total DM accumulation and partitioned greater amounts into the reproductive plant parts （panicles） but also results in higher harvest index.

Erect panicle super rice varieties enhance yield by harvest index advantages in high nitrogen and density conditions

The erect panicle （Ep） type is an important characteristic for japonica super rice in Northeast China and plays a significant role in enhancing yield. The Ep type is considered to be a genetic ideotype resource to the japonica super rice group by virtue of its agronomic advantages such as grain number per panicle and biomass. This study addresses the effects of nitrogen and planting density conditions on yielding performance regarding panicle type （PT） using the recombinant inbred line （RIL） population derived from the cross between an Ep variety Liaogeng 5 and non-Ep variety Wanlun 422. The genetics underlying the Ep type proved to be robust not only for panicle-type optimization but also plant height, panicle length, flag leaf length and seed density. We also found that regardless of nitrogen and density, correlation between harvest index （HI） and plant height was not significant in Ep type whatever the nitrogen and density. The application of Ep type provides a potential strategy for yield improvement by increasing biomass through HI maintainable in rice.

Contrasting Characteristics of Lodging Resistance in Two Super-Rice Hybrids Differing in Harvest Index

The“super rice”breeding program in China has been successful in developing high-yielding hybrids,including few with high harvest index values.However,there is limited information on the relationship between lodging resistance and harvest index,and the mechanisms underlying the relationship in super-rice hybrids.In this study,a two-year field experiment was conducted to compare lodging resistance and its related traits between two superrice hybrids differing in harvest index,i.e.,Guiliangyou 2(G2)with a high harvest index and Y-liangyou 1(Y1)with a typical harvest index of modern high-yielding rice varieties.Results showed that compared to Y1,G2 was lower in plant height due to its lower aboveground N uptake,and its higher stem breaking resistance(i.e.,lower stem breaking index)resulted from a lower stem height at its center of gravity.Consequently,G2 had a higher lodging resistance(i.e.,lower plant lodging index)than Y1.This study suggests that developing super-rice hybrids with high harvest index values is a possible way to achieve both high grain yield and strong lodging resistance in rice.

Effects of drip and flood irrigation on carbon dioxide exchange and crop growth in the maize ecosystem in the Hetao Irrigation District,China

Drip irrigation and flood irrigation are major irrigation methods for maize crops in the Hetao Irrigation District,Inner Mongolia Autonomous Region,China.This research delves into the effects of these irrigation methods on carbon dioxide(CO_(2))exchange and crop growth in this region.The experimental site was divided into drip and flood irrigation zones.The irrigation schedules of this study aligned with the local commonly used irrigation schedule.We employed a developed chamber system to measure the diurnal CO_(2)exchange of maize plants during various growth stages under both drip and flood irrigation methods.From May to September in 2020 and 2021,two sets of repeated experiments were conducted.In each experiment,a total of nine measurements of CO_(2)exchange were performed to obtain carbon exchange data at different growth stages of maize crop.During each CO_(2)exchange measurement event,CO_(2)flux data were collected every two hours over a day-long period to capture the diurnal variations in CO_(2)exchange.During each CO_(2)exchange measurement event,the biological parameters(aboveground biomass and crop growth rate)of maize and environmental parameters(including air humidity,air temperature,precipitation,soil water content,and photosynthetically active radiation)were measured.The results indicated a V-shaped trend in net ecosystem CO_(2)exchange in daytime,reducing slowly at night,while the net assimilation rate(net primary productivity)exhibited a contrasting trend.Notably,compared with flood irrigation,drip irrigation demonstrated significantly higher average daily soil CO_(2)emission and greater average daily CO_(2)absorption by maize plants.Consequently,within the maize ecosystem,drip irrigation appeared more conducive to absorbing atmospheric CO_(2).Furthermore,drip irrigation demonstrated a faster crop growth rate and increased aboveground biomass compared with flood irrigation.A strong linear relationship existed between leaf area index and light utilization efficiency,irrespective of the irrigation method.Notably,drip irrigation displayed superior light use efficiency compared with flood irrigation.The final yield results corroborated these findings,indicating that drip irrigation yielded higher harvest index and overall yield than flood irrigation.The results of this study provide a basis for the selection of optimal irrigation methods commonly used in the Hetao Irrigation District.This research also serves as a reference for future irrigation studies that consider measurements of both carbon emissions and yield simultaneously.

陇东旱塬区宜机收玉米品种的性状指标综合评价

目前玉米生产机械化程度越来越高,玉米籽粒机收将是大势所趋,因此人们对玉米品种的选择也趋向于耐密植、抗倒伏和籽粒脱水快等优良性状。为了筛选出陇东旱塬区适宜的籽粒机收玉米品种,通过灰色关联度分析法对引进的17个玉米品种表型性状和籽粒机收适宜性进行综合评价。结果表明,和恒5266产量高,但是机收表现不理想;迪卡159、先丰9号、先玉1483、五谷737和新农育6003等5个品种综合表现良好,可以作为陇东旱塬区籽粒机收玉米品种贮备品种加以推广,尤其是五谷737产量高、抗性好、机收表现好,宜大力推广种植。

生物炭类型和施用量对陕北黄绵土土壤理化性状和谷子生长的影响

【目的】探明不同生物炭类型和施用量对陕北黄绵土理化性状和谷子生长的影响。【方法】选取玉米秸秆(JG)、稻壳(DK)和竹竿(ZG)3种生物炭,分别设置C1(300 g/m^(2))、C2(600 g/m^(2))、C3(1200 g/m^(2))3个施炭水平,以不施生物炭为对照(CK),开展谷子室内模拟栽培试验,通过测定土壤理化指标和谷子生长指标,探究不同生物炭类型和施用量对陕北黄绵土土壤理化性状及谷子生长的影响。【结果】DK生物炭对土壤含水量和容重有显著的调控作用,DKC2处理的土壤含水量较JGC2和ZGC2处理分别显著下降15.78%、18.26%(P<0.05);DKC3处理的土壤容重较JGC3和ZGC3分别显著下降20.07%、24.63%(P<0.05);施ZG生物炭时,土壤有机碳、速效钾含量随生物炭施用量增加逐渐递增,ZGC3处理下,土壤有机碳、速效钾含量较CK分别显著提升134.35%、77.94%(P<0.05)。施JG生物炭时,谷子株高、地上部干重随生物炭施用量的增加先增后减,且JGC2处理下谷子株高、地上部干重较CK分别显著提升32.62%、77.13%(P<0.05),单穗粒重、总干重及小区产量较施DKC2、ZGC2处理分别显著提升126.18%、65.36%、57.54%和79.25%、82.46%%、50.37%(P<0.05)。施DK生物炭的谷子地下部干重、根表面积和根冠比随生物炭施用量的增加先增后减,DKC2处理谷子地下部干重、根表面积和根冠比较CK分别显著提升104.53%、90.30%、82.11%(P<0.05);ZGC3处理谷子收获指数较施DKC3显著提升50.00%(P<0.05)。【结论】不同生物炭类型及施用量对谷子的生长影响各异,600 g/m^(2)玉米秸秆生物炭处理更利于谷子干重的提升、600 g/m^(2)稻壳生物炭处理更利于谷子根系的生长、1200 g/m^(2)竹竿处理更利于谷子收获指数的提升。在陕北黄绵土中种植谷子,施玉米秸秆、竹竿生物炭具有较好的土壤水肥调节能力和增产增效作用。

Assessing the influence of harvesting intensities on structural diversity of forests in south-west Germany

Background: To increase ecosystem resilience and biodiversity, the maintenance and improvement of structural and compositional diversity of forests has become an important goal in forest management for many forest owners and jurisdictions. At the same time, future harvesting intensity (HI) may increase to meet the demand for woody biomass by an increasing bioeconomy sector. Yet, the influence of HI on forest structural diversity is largely unknown. Here, we address this issue by analyzing the relationship between HI and structural diversity based on large-scale national forest inventory (NFI) data, where the latter is quantified using a previously developed Forest Structure Index and HI is expressed as wood volume removal during the period 2002-2012 for the same inventory plots. Results: Our results show a surprisingly small impact of harvesting intensity on changes in structural diversity for most of the analysed types of forests. Only intense harvesting (> 80%-90% of initial growing stock) led to a significant reduction in structural diversity. At low to moderate HI most aspects of structural diversity were positively influenced. Only the quadratic mean DBH and the volume of large trees (≥ 40 cm DBH) were substantially negatively influenced at HI > 60% and 70% of initial growing stock, respectively. Conclusions: In several forest types, HI could be increased without a reduction in overall structural diversity. Hence, structural diversity in these selectively managed forests appears to be a very resistant forest property in relation to HI. Other indicators at stand and landscape scale may be needed to adjust levels of HI that are suited to maintain forest biodiversity.

Energy-Harvesting Systems for Green Computing

Energy harvesting technologies provide a promising alternative to battery-powered systems and create an opportunity to achieve sustainable computing for the exploitation of ambient energy sources. However, energy harvesting devices and power generators encompass a number of non-classical system behaviors or characteristics, such as delivering nondeterministic power density, and these would create hindrance for effectively utilizing the harvested energy. Previously, we have investigated new design methods and tools that are used to enable power adaptive computing and, particularly, catering non-deterministic voltage, which can efficiently utilize ambient energy sources. Also, we developed a co-optimization approach to maximize the computational efficiency from the harvested ambient energy. This paper will provide a review of these methods. Emerging technologies, such as 3D-IC, which would also enable new paradigm of green and high-performance computing, will be also discussed.

Balancing timber production and habitat conservation of Okinawa Rails(Gallirallus okinawae): Application of a harvest scheduling optimization model in subtropical forest in Okinawa, Japan

Finding the right balance between timber production and the management of forest-dependent wildlife species,present a difficult challenge for forest resource managers and policy makers in Okinawa,Japan.A possible explanation of this can be found in the unique nature of the forest management area which is populated with various kinds of rare and endangered species.This issue has been brought to light as a result of the nomination of northern Okinawa Island in 2018 as a candidate for World Natural Heritage site.The nomination has raised public awareness to the possibility of conflicting management objectives between timber extraction and the conservation of habitat for forest-dependent wildlife species.Managing exclusively for one objective over the other may fail to meet the demand for both forest products and wildlife habitat,ultimately jeopardizing the stability of human and wildlife communities.It is therefore important to achieve a better balance between the objective of timber production and conservation of wildlife habitat.Despite the significance of this subject area,current ongoing discussions on how to effectively manage for forest resources,often lack scientific basis to make sound judgement or evaluate tradeoffs between conflicting objectives.Quantifying the effect of these forest management activities on wildlife habitat provides useful and important information needed to make forest management and policy decisions.In this study we develop a spatial timber harvest scheduling model that incorporates habitat suitability index(HSI)models for the Okinawa Rail(Gallirallus okinawae),an endangered avian species found on Okinawa,Japan.To illustrate how the proposed coupling model assembles spatial information,which ultimately aids the study of forest management effects on wildlife habitat,we apply these models to a forest area in Okinawa and conduct a simple simulation analysis.

机采棉种植模式下不同棉花品种适应性研究

明确各品种在机采棉种植模式下形态、生理及产量因子变化,为长江流域棉花机械化生产中品种选择提供理论基础。通过2018—2019年大田试验,以‘中棉所63F2’(杂交棉品种)低密度(4.5万株/hm^(2))为对照,研究‘中棉所63F2’和‘中棉所425’(常规早熟棉品种)、‘中棉所50’(常规早熟棉品种)等3个棉花品种在高密度(9.0万株/hm^(2))机采棉种植模式下的品种生育进程、农艺性状、干物质积累及产量变化。结果表明,各品种在机采棉种植模式下,其叶面积指数、干物质积累量、成铃数及产量均高于对照;‘中棉所63F2’单铃重、籽棉产量高于2个常规早熟棉花品种,但未达显著水平。常规早熟棉品种‘中棉所425’、‘中棉所50’成熟较早、集中成铃,适宜长江流域一年两熟模式下连茬种植。

Ideal Point Method Applied in Forest Harvest Regulation

Ideal point method is one of the methods to solve multi-objective problem. It is applied to forest harvest regu-lation, and showed very good results by analyzing changes of quantitative indexes of forest resource structure before andafter the regulation. This method can be applied as one of the mathematical tools in forest harvest regulation.

Effect of Lime and Phosphorus on Yield and Yield Components of Groundnut Varieties [Arachis hypogaea L.] on Acidic Soil in Nedjo District, Western Ethiopia

Groundnut (Arachis hypogaea L.) is an important cash crop for smallholder farmers in western Ethiopia. However, the yield of the crop is very low mainly because of strong soil acidity and poor soil fertility management. A study conducted to evaluate the effect of lime and mineral phosphorus fertilizer on yield components and yield of groundnut. The treatments consisted of three phosphorus rates (0, 46 and 92 kg P2O5·ha-1), three lime rates (0, 6, and 11 ton lime·ha-1), and three groundnut varieties (local cultivar, Werer-961, and Werer-963) was laid-out as a randomized complete design in a factorial arrangement with three replications. The corresponding rates of phosphorus applied per pot of soil (7 kg) amounted to 0, 107 and 215 mg kg·soil-1 and those of lime amounted to 0, 14, and 26 g kg·soil-1. The analysis of variance showed that phenological characters, yield, and yield components significantly affected by interaction of variety, phosphorus, and lime. The highest dry pod yield produced by Werer-963 (2 kg dry pod yield·pot-1) in response to the application 11 t·ha-1 lime and 46 kg P2O5·ha-1. However, Werer-961 produced medium (1.5 kg dry pod yield·pot-1) at 11 t·ha-1 lime and 92 kg P2O5·ha-1 and the local cultivar produced minimum (1 kg dry pod yield·pot-1) at the application of 11 t·ha-1 lime and 92 kg P2O5·ha-1. In terms of phosphorus yield efficiency index, Werer-963 was highly efficient (index of 1.71), and Werer-961 was moderately efficient (index of 0.6). However, the local cultivar was inefficient (index of 0.04). It is at, in acidic soil of the study area Werer-963 is the best to be cultivated with application of lime 11 t·ha-1 and 46 kg P2O5·ha-1 fertilizer, followed by Werer-961. The results of this pot experiment have revealed that farmers in the study area need to switch to cultivating the improved varieties of groundnut rather than local variety with the application of high rates of lime and moderate amounts of phosphorus.

控制排水条件下黄豆氮磷吸收利用及产量的试验研究

为揭示控制排水条件下黄豆氮磷吸收利用及产量的影响机理,2019—2020年连续2年在湖北省漳河灌区开展了自由排水(埋深1.2 m)、定水位排水(埋深0.6 m)、变水位排水(埋深0.4~0.8 m)3种排水处理条件下黄豆种植小区试验。试验结果表明:定水位排水处理条件下的黄豆产量最高,分别为1795.5 kg/hm^(2)(2019年)和2118.2 kg/hm^(2)(2020年);氮、磷吸收利用效率在定水位排水处理条件下的最大,氮肥偏生产力分别为7.70 kg/kg(2019年)、9.08 kg/kg(2020年),磷肥偏生产力分别为15.42 kg/kg(2019年)、18.19 kg/kg(2020年);定水位排水处理条件下的氮素收获指数为最高,达50.0%(2020年),比自由排水处理条件下和变水位排水处理条件下的分别高2.3%和2.8%;磷素收获指数也是在定水位排水处理条件下的最高,为37.6%(2020年),比自由排水处理条件下和变水位排水处理条件下的分别高3.1%和0.7%。定水位排水处理条件(埋深0.6 m)不仅有利于提高黄豆的产量,同时也有利于提高植株的氮、磷肥吸收利用效率,是漳河灌区黄豆种植较优的排水处理模式。

不同油菜品种及栽培措施对收获指数的影响

【目的】研究不同油菜品种与栽培措施下收获指数(HI)与籽粒产量、角果皮等不同器官成熟期干重的关系,同时分析油菜品种育成年代、株高和冬性特征对收获指数的影响,为高产、高效油菜品种的选育和栽培措施的协同优化提供参考。【方法】以近年来长江流域推广的不同育成年代、株高及冬性特征的60个油菜品种为材料,于2016—2017年分别在湖北和贵州两地开展品种大田试验;于2017—2020年在贵州碧江、思南和江口3点开展以不同播种期、肥力水平、种植密度和行距配置等栽培因子的组合试验,开展油菜栽培措施优化组合的大田试验,在油菜成熟期采样后测定各部分干重及产量,计算分析收获指数。【结果】不同油菜品种的收获指数变化差异最高达367%,不同农艺栽培措施组合使其收获指数差异达52%—117%。不同品种油菜的收获指数每增加0.1,大田籽粒产量在两个试验点分别提高305和385 kg·hm^(-2);不同农艺栽培措施优化后籽粒产量随油菜收获指数的提高而增加,收获指数每增加0.1则大田籽粒产量增加505—1690 kg·hm^(-2)。不同品种和栽培措施影响下,油菜的收获指数与植株的主茎籽粒产量、分枝籽粒产量和地上部生物产量均呈正相关关系;不同栽培措施优化后油菜收获指数与角果皮干重呈正相关关系;而不同品种和栽培措施的油菜收获指数与茎秆干重没有较一致的相关性。2010年以前与2015年以后育成的油菜品种间收获指数有显著差异;株高小于170 cm的油菜品种其收获指数值相对较高,高秆品种的收获指数显著低于矮秆和中秆品种;弱冬性、半冬性和冬性油菜品种之间收获指数无显著差异。【结论】油菜不同品种选择和栽培因子的优化组合措施对其收获指数有显著影响,可选育较高收获指数油菜品种推广,同时通过优化组合栽培技术措施适当增加大田油菜群体收获指数,通过良种和良法的协同来提高大田油菜籽粒产量。近年在长江流域选育推广的油菜品种收获指数受其育成年代和株高影响显著,而品种间的冬性差异对油菜收获指数无显著影响。

氮肥和品种及种植密度对春玉米机械化收获性状及产量的影响

机械化收获是提高农业生产效率的重要措施,但机械化收获受倒伏、籽粒脱水特性和收获籽粒含水率等的影响。为探讨春玉米形态结构与抗倒伏性之间的关系,籽粒脱水进程和收获籽粒含水率对品种、施氮量和种植密度的响应,该研究以先玉335和陕单609为试验材料,设置0、180和225 kg/hm^(2)三个氮肥水平,6.5×10^(4)和8.5×10^(4)株/hm^(2)两个种植密度,通过2 a大田试验研究品种、种植密度和氮肥对株高、茎粗、穗位系数、抗折强度、弯曲力矩、倒伏系数、灌浆末期籽粒脱水速率、收获籽粒含水率、产量和生物量等的影响。结果表明:不施氮条件下,株高和茎粗对倒伏系数影响较大;施氮条件下,倒伏系数主要受弯曲力矩、抗折强度和株高影响。施氮显著降低陕单609的倒伏系数(P<0.05),施氮处理下陕单609的株高和茎粗较不施氮处理分别增加8%~21%和26%~45%,抗折强度和弯曲力矩分别增加157%~277%和72%~114%,倒伏系数降低30%~47%。施氮可降低籽粒脱水速率,推迟脱水进程,显著增加收获籽粒含水率(P<0.05)。施氮处理籽粒含水率较不施氮处理提高7%~9%。高密度处理收获籽粒含水率比低密度处理低3%(P<0.05)。先玉335的籽粒脱水速率快,收获籽粒含水率比陕单609低7%(P<0.05)。与不施氮处理相比,施氮处理产量和生物量分别显著提高92%和63%(P<0.05)。与低密度处理相比,高密度处理产量显著增加12%(P<0.05)。综上所述,春玉米的倒伏性、灌浆后期籽粒脱水速率及收获籽粒含水率受品种特性影响,也受施肥、栽培措施和气候条件的显著影响。选育籽粒脱水快的品种、适当增加种植密度并合理统筹氮肥施用量可以提高春玉米机械化收获适宜性。

不同灌溉条件下氮肥配施模式对水稻干物质和产量的影响

【目的】明确不同灌溉模式下普通尿素与控释尿素配施对水稻干物质积累、分配和产量的影响。【方法】以“超级稻-两优152”为供试作物,采取完全随机设计,灌溉方式设置常规灌溉(CF)和干湿交替灌溉(AWD)2种,氮肥配施模式设置100%普通尿素(N1),60%控释尿素+40%普通尿素(N2)和100%控释尿素(N3),施氮总量均为240 kg/hm^(2)。测定不同处理组合下各生育期水稻叶片SPAD值、株高、抽穗期和成熟期各器官干物质量、茎蘖数、籽粒产量及其构成因素。【结果】同一施氮模式下,与CF处理相比,AWD处理下拔节—灌浆期水稻叶片的SPAD值、作物生长速率、茎蘖成穗率、干物质积累量及其向籽粒的分配比例增加。同一灌溉模式下,与N1处理相比,N2、N3处理的茎蘖成穗率、作物生长速率、干物质积累量、穗粒数、千粒质量、结实率及籽粒产量增加,其中N2处理籽粒产量的增加幅度要高于N3处理。整体来看,与其他处理相比,AWDN2处理获得较高的SPAD值、茎蘖成穗率、作物生长速率、干物质积累量、收获指数、穗粒数、千粒质量、结实率和籽粒产量。【结论】干湿交替灌溉耦合60%控释尿素+40%普通尿素有利于减少水稻的无效分蘖,改善植株的氮营养状况,促进干物质的积累及其向籽粒的分配,从而提高产量。

机收夏玉米施肥方案对收获指数的影响

为解决机收夏玉米成熟期短、脱水慢、栽培密度高(≥7.5×100株/hm^(2))、收获指数低等造成的减产问题,以机收夏玉米‘郑单958’为试验材料,分析不同施肥方案对玉米叶片生长面积、营养质量和籽粒产量的影响,实验结果表明,与原肥料施肥做相比,添加甜菜碱的肥料,在试验第10~60d时,加入甜菜碱施肥后的夏玉米叶面积指数为3.92,正常施肥的叶面积为4.43,证明适量浓度的甜菜碱处理可以使夏玉米的叶面积增长趋于稳定;同时发现,相比挖坑撒施,地面撒施所保留的营养成分更全面,各项指标略高一些;不同行距对于夏玉米收获指数影响差异显著,收获指数与产量呈正比,宽窄行距显著优于等行距模式,建议夏玉米使用宽窄行距施肥,以期提高收获指数与产量,实现籽粒机收。

亏缺灌溉下小麦水分利用效率与光合产物积累运转的相关研究

在大田栽培条件下,以小麦旱地品种晋麦47和西峰20、水旱兼用型品种石家庄8号和水地品种4185为材料,分别进行0水(T0)、一水(T1)和二水灌溉(T2)处理(每次灌水量60mm),研究了光合速率、叶面积指数、干物质积累与分配、根系分布、耗水量、产量因子与水分利用效率(WUE)的关系。结果表明,在拔节前不灌溉,拔节到开花期亏缺灌溉,促进干物质积累和深根发育。随着灌溉水的增加,耗水量显著增加,产量和WUE与耗水量呈二次曲线关系。T0处理显著减少了干物质积累和成穗数,产量、经济系数(HI)和WUE最低。T1和T2产量的提高主要是增加了穗数和穗粒数。灌浆期水分亏缺降低了光合速率(Pn)和气孔导度(Gs),加速了功能叶片的衰老,但诱导了花前储存碳库的再转运,显著提高了HI和产量。因此,在拔节和开花期亏缺灌溉促进根系生长,提高了土壤水分的利用效率。而产量和产量WUE的提高主要是由于增加了灌浆期叶片的Pn和光合功能持续期,促进花前储存碳库的再转运,显著提高了HI。

生物炭对夏玉米生长和产量的影响

通过大田试验,在夏玉米（Zea mays L.）主要生育时期测定叶片叶绿素含量、净光合速率、叶面积指数（LAI）、干物质重等指标,在成熟期测定产量,分析生物炭不同施用量[0（CK）、1000 kg·hm^-2（T1）,5000 kg·hm^-2（T2）,10 000 kg·hm^-2（T3）]对夏玉米生长和产量的影响。结果表明,不同量的生物炭施用均能显著提高夏玉米产量,其中T1增产幅度最大,达8.8%;产量构成因素表现为穗粒数T3显著高于T1和CK,百粒重T1显著高于T3和CK。生物炭显著影响LAI、叶片净光合速率、叶绿素含量、干物质积累等指标,T2、T3处理能显著增加夏玉米地上部干物质重,在各生育时期分别高于对照9.2%～20.5%和11.5%～36.7%;在生长前期表现为高生物炭施用量更有利于叶面积指数的增加和光合速率的提高,但生长后期,较低量的生物炭施用更有利于叶片的持绿和光合作用的持续,而较高量的生物炭施用下生育后期植株有早衰迹象,从收获指数来看,T1收获指数达57.4%,分别显著高于T2、T3和CK8.3%、13.2%和6.5%,这表明低施用量生物炭更有利于夏玉米光合产物向籽粒的转运。综合来看,生物炭施用有利于夏玉米的干物质积累,尤其是较低的生物炭施用量更有利于后期叶片光合性能的维持和籽粒产量的提高。