Effects of root pruning on the growth and water use efficiency of winter wheat

A pot experiment was conducted to study the effects of root pruning at the stem elongation stage on the growth and water use efficiency (WUE) of winter wheat (Triticum aestivum). The results showed that stomatal conductance (g) and transpiration (E) of wheat were very sensitive to root pruning. After root pruning, they declined rapidly and but returned to pre-pruning values 15 days after treatment. Under well-watered conditions, there was no significant difference in leaf water potential (ψ_leaf) between root pruned and control plants after root pruning. Under moderate drought stress, ψ_leaf of root pruned plants declined significantly compared to the control 3 days after root pruning. After 15 days, ψ_leaf of root pruned plants was similar to the controls. Under different soil moisture levels, net assimilation rate (A) of root pruned plants was lower than controls 3–7 days after root pruning, but was similar to the controls 15 days after pruning. At anthesis (50 days after root pruning), root pruned plants showed significantly higher A compared with the control. Leaf area per tiller and tiller number of root pruning plants was significant lower than the control at booting stage, which showed that root pruning restrained the growth of plants in the early growing stage, but leaf area per stem, of root pruned plants, was similar to the control at anthesis. Under both soil moisture levels, there was no significant difference in grain yield between root pruned and the control plants in the monoculture. In mixture with the control plants, the root pruned plants was less productive and had a lower relative yield (0.92 and 0.78, respectively) compared with the control (1.13 and 1.19, respectively), which suggested that the pruned plants lost some of its competing ability and showed a lower ability to acquire and use the same resources in the mixture compared with the control plant. Over the whole growing cycle, root pruning reduced water consumption (by 10% under well-watered conditions and 16% under moderate drought stress) of wheat significantly compared to the control (P < 0.05), and but there was no significant difference in grain yield between root pruned and control plants. Therefore root pruned wheat had a higher WUE with respect to grain yield compared with the controls. In conclusion, lowering water consumption by root pruning in the early growing stage is an effective way to improve water use efficiency in arid and semi arid areas.     

灌浆期不同阶段遮光对小麦籽粒蛋白质组分含量和加工品质的影响

选用强筋小麦济麦20、中筋小麦泰山23和弱筋小麦宁麦9号3个小麦品种,设置了灌浆期不同阶段遮光处理:开花后不遮光(S0)、0～11 d遮光(S1)、12 ～23 d遮光(S2)、24～35 d遮光(S3),研究了其对不同小麦品种籽粒蛋白质组分含量和加工品质的影响.结果表明:3个小麦品种的籽粒清蛋白+球蛋白含量遮光处理间无显著差异;遮光均显著提高了济麦20和泰山23的高分子量谷蛋白亚基、低分子量谷蛋白亚基、谷蛋白、醇溶蛋白和总蛋白含量,其中灌浆中期遮光(S2)处理提高幅度高于其他处理;灌浆中期(S2)和后期(S3)遮光处理显著提高了宁麦9号各蛋白质组分含量.遮光显著降低了小麦籽粒产量,提高了籽粒面团形成时间、面团稳定时间和沉降值,其中灌浆中期遮光处理更为显著,表明籽粒品质的形成与灌浆中期的光照条件更为密切.总体上灌浆期遮光对3个小麦品种籽粒产量、蛋白质组分含量及加工品质指标的调节幅度为济麦20＞泰山23＞宁麦9号.     

氮、硫肥与灌浆后期高温胁迫对小麦籽粒产量和品质的影响

灌浆期高温胁迫通常导致小麦籽粒产量降低、品质变差.为了探索有效缓解高温胁迫不利影响的有效措施,在大田条件下,以济麦20为试验材料,运用后期高温棚增温的方法,研究了氮、硫肥与灌浆后期高温对小麦籽粒产量和品质的影响.结果表明:高温处理后小麦千粒质量、籽粒产量显著降低(19.7%～28.3%),蛋白质含量升高,蛋白质组分中不溶性谷蛋白含量下降,可溶性谷蛋白含量上升,面团形成时间和稳定时间缩短;氮肥追施比例由50%增加到70%,非高温处理的籽粒产量无显著变化,不溶性谷蛋白质含量和谷蛋白聚合指数(不溶性谷蛋白含量/可溶性谷蛋白含量)升高,面团形成时间和稳定时间延长;高温处理的千粒质量和籽粒产量因氮肥追施比例提高而提高(2.07%～3.58%),面团形成时间和稳定时间缩短;不论高温处理还是非高温处理,与追施硫肥相比,硫肥基施提高籽粒产量、谷蛋白聚合指数,延长面团形成时间和稳定时间;为了有效缓解灌浆后期高温对小麦籽粒产量和品质的不利影响,硫肥基施、氮肥施用基追比50%:50%是较为适宜的施肥模式.     

冠层温度与冬小麦农田生态系统水分状况的关系

1　引　　言通过表面温度遥感监测作物和土壤水分一直是一个共同关注的问题,而该问题解决的一个基础是冠层温度与农田土壤湿度和作物水分状况的关系的研究.国内这方面的研究起步于80年代并已取得一些结果[1～3].但主要集中在冠层空气温度差与农田土壤湿度的关系上,对于冠层温度     

冬小麦生长季不同灌溉模式对冬小麦-夏玉米产量与水分利用的影响

在华北平原黑龙港流域对冬小麦实行3种灌溉模式,研究了不同灌溉模式对冬小麦-夏玉米产量、耗水特性和水分利用效率的影响.结果表明:浇底墒水+拔节水处理(W2,75 mm+90 mm)和浇底墒水+拔节水+灌浆水处理(W3,75 mm+90 mm+60 mm)周年总产量均显著高于只浇底墒水处理(W1,75 mm),增幅分别为8.7%和12.5%.冬小麦全生育期对土壤水的消耗随灌溉量的增加而减少,夏玉米季总耗水量随冬小麦季灌溉量的增加而增加.W2处理冬小麦水分利用效率(WUE)比W3处理高11.1%,而其夏玉米水分利用效率(WUE)与W3处理差异不显著.W2和W1处理的周年水分利用效率(WUET)分别为21.28和21.60 kg.mm-1.hm-2,比W3处理分别高7.8%和9.4%.综合周年产量、耗水量和水分利用效率,W2是较好的节水丰产灌溉模式.     

土壤深层供水对冬小麦干物质生产的影响

采用根系研究装置研究了土壤深层供水对冬小麦干物质生产的影响 .结果表明 ,上层低湿度下层高湿度的处理在小麦灌浆期仍然保持了较高的土壤和叶片含水量 ,具有发达的根系 ,特别是 1m以下的根量在 4个处理中为最高 ,旗叶和穗的干重也最大 ,具有最大的产量潜力 .本研究表明 ,上层土壤较干下层土壤湿润有利于发挥小麦根信号的积极作用 ,平衡水分利用 ,同时通过对土壤水分的合理调节可以促进深层根的发育 ,有利于提高产量和水分利用效率 .     

Analysis of spatial and yearly variation in winter survival of winter wheat

 Four years of winter survival data for winter wheat (Triticum aestivum L.) were collected on a loam soil located on the Central Experimental Farm at Ottawa, Ontario (45° 23′N, 75° 43′W). The site was low-lying and subject to frequent winter flooding and ice sheet formation. It appeared level although there was microtopographic variation with a range in elevation of approximately 0.15 m. The objective of the study was to gain insight into factors which might affect winter survival. Two varieties, a soft white and a hard red winter wheat, were planted in September. Crop establishment was measured in late fall and the percentage survival was measured in April of the following year. We assumed the large spatial differences in survival were not totally random, but rather were affected by spatial variation in environmental factors such as snow and ice depth, soil moisture and temperature. Hourly measurements of soil temperature at a depth of 0.05 m were recorded throughout the fall, winter and spring. Fall and spring soil moisture at the same depth were measured on the plot, as well as snow and ice depth at selected times throughout the winter. Measurements were taken on a grid covering the plot to help explain spatial variation in survival. In addition, detailed measurements of elevation were taken on a grid. Meteorological data were available from the nearby weather site. While soil temperatures were never low enough to kill plants according to the CERES model, the spatial variation in winter survival was associated with differences in elevation and the resulting surface drainage patterns. Received: 23 March 1998/Accepted: 21 October 1998     

Leaf senescence and grain filling affected by post-anthesis high temperatures in two different wheat cultivars

High temperature is a major factor affecting grain yield and plant senescence in wheat growing regions of central and east China. In this study, two different wheat cultivars, Yangmai 9 with low-grain protein concentration and Xuzhou 26 with high-grain protein concentration, were exposed to different temperature regimes in growth chambers during grain filling. Four day/night temperature regimes of 34°C/22°C, 32°C/24°C, 26°C/14°C, and 24°C/16°C were established to obtain two daily temperatures of 28 and 20°C, and two diurnal day/night temperature differences of 12 and 8°C. Concentration of a lipid peroxidation product malondialdehyde (MDA), activities of the antioxidants superoxide dismutase (SOD) and catalase (CAT), chlorophyll concentration (SPAD) in flag leaves and kernel weight were determined. Results show that activities of SOD and CAT in leaves increased markedly on 14 days after anthesis (DAA) for the high-temperature treatment (34°C/22°C) and then declined. As a result, MDA concentration in leaves increased significantly under high temperature (34°C/22°C and 32°C/24°C). Compared with optimum temperature treatment, high temperature reduced the concentration of soluble protein and SPAD values in flag leaves. Grain-filling rate increased slightly initially, but decreased significantly during late grain filling under high temperature. As a result, final grain weight was reduced markedly under high temperature. Decreases in the activities of SOD and CAT and increases in MDA concentration in leaves were more pronounced with a 12°C of day/night temperature difference when under high temperatures. Kernel weight was higher under 12°C of day/night temperature difference under optimum temperatures (24°C/16°C and 26°C/14°C). The responses to high-temperature regimes appeared to differ between the two wheat cultivars with different grain protein concentrations. It is concluded that a larger diurnal temperature difference hastened the senescence of flag leaves under high-temperature conditions, but retarded senescence under optimum temperature treatments of 26°C/14°C and 24°C/16°C.     

Contributions of root uptake and remobilization to grain zinc accumulation in wheat depending on post-anthesis zinc availability and nitrogen nutrition

Background and aims

Whether root Zn uptake during grain filling or remobilization from pre-anthesis Zn stores contributes more to grain Zn in wheat is subject to an on-going debate. This study investigated the effects of N nutrition and post-anthesis Zn availability on the relative importance of these sources.

Methods

Durum wheat plants were grown in nutrient solution containing adequate Zn (0.5?μM) and three different N levels (0.5; 1.5; 4.5?mM). One third of the plants were harvested when they reached anthesis. One half of the remaining plants were grown to maturity with adequate Zn, whereas the Zn supply to the other half was discontinued at anthesis. Roots, straw and grains were harvested separately and analyzed for Zn and N.

Results

Depending on the N supply, Zn remobilization from pre-anthesis sources provided almost all of grain Zn when the Zn supply was withheld at anthesis; otherwise up to 100?% of grain Zn could be accounted for by Zn taken up post-anthesis. By promoting tillering and grain yield and extending the grain filling, higher N supply favored the contribution of Zn uptake to grain Zn accumulation.

Conclusion

Remobilization is critical for grain Zn accumulation when Zn availability is restricted during grain filling. However, where root uptake can continue, concurrent Zn uptake during grain development, favored by higher N supply, overshadows net remobilization.     

Effects of waterlogging and drought on winter wheat and winter barley grown on a clay and a sandy loam soil

Summary The effects of winter waterlogging and a subsequent drought on the growth of winter barley and winter wheat have been examined. We used lysimeters containing soil monoliths with facilities to control the water table and a mobile shelter to control rainfall. Winter wheat was grown on a clay and on a sandy loam, but winter barley only on the clay soil. Lysimeters were either freely-drained during the winter or waterlogged with the water table 10 cm below the soil surface from 2 December until 31 March (that could occur by rainfall with a return period of 2 to 3 years). The lysimeters then were either irrigated so that the soil moisture deficit did not exceed 84 mm, or subjected to drought by limiting rainfall (equivalent to a 1 in 10 dry year in the driest area of England) so that the deficits reached maximum values of 150 mm in the clay and 159 mm in the sandy loam by harvest.Winter waterlogging restricted tillering and restricted the number of ears for all crops; grain yield of the winter barley was decreased by 219 g/m² (30%), and that of winter wheat by 170 g/m² (24%) and 153 g/m² (21% on the clay and sandy loam respectively.The drought treatment reduced the straw weight of winter barley by 75 g/m² (12%) but did not significantly depress the grain yield. For winter wheat on the clay, where the soil was freely-drained during the winter, drought depressed total shoot weight by 344 g/m² (17%) and grain weight by 137 g/m² (17%), but after winter waterlogging, drought did not further depress total or grain weight. In contrast, the winter wheat on the sandy loam was not significantly affected by drought.From these results, which are discussed in relation to other experiments in the United Kingdom, it seems that winter waterlogging is likely to cause more variation in the yield of winter barley and winter wheat than drought.     

不同带长微喷带灌溉对土壤水分布与冬小麦耗水特性及产量的影响

于2010—2012年度冬小麦生长季,选用高产冬小麦品种济麦22,采用测墒补灌方式,设置40m(T40)、60m(T60)和80m(T80)3种带长的微喷带灌溉处理,研究不同带长微喷带灌溉对土壤水分分布及冬小麦耗水特性和产量的影响.结果表明:拔节期和开花期采用微喷带补灌,随微喷带带长缩短,灌溉水在土壤中的水平分布均匀系数显著增加.拔节期补灌,T40和T60处理在距畦首0～40m范围内各小麦行间的0～200cm土层土壤含水量均无显著差异;T80处理在距畦首38～40m、58～60m和78～80m处各小麦行间的0～200cm各土层土壤含水量变化规律一致,均表现为随距微喷带的距离增加而减小.T40处理的小麦在拔节至开花期间和开花至成熟期间分别对40～60cm和20～80cm土层土壤贮水的消耗量显著高于T60和T80处理,而对深层土壤贮水消耗量和总土壤贮水消耗量、开花期补灌水量、总灌水量和总耗水量显著低于T60和T80处理.随微喷带带长缩短,小麦籽粒产量、产量水分利用效率显著升高,而流量降低,在灌水量一定的情况下,单位时间内的有效灌溉面积减小.综合考虑小麦籽粒产量、水分利用效率和流量,40和60m是本试验条件下的适宜微喷带带长.     

冬小麦干物质在各器官中的累积和分配规律研究

为修正冬小麦生长模型中的干物质分配,通过田间试验,对冬小麦干物质累积和在不同器官中的分配进行了描述。并且在此基础上结合文献资料,对冬小麦光合产物在各器官中的分配和转移系数的计算方法进行了探讨,分析了两者随相对发育阶段（RDS）的变化规律,并建立了函数表。同时运用试验资料进行了实地验证,取得较好的效果。     

黄土高原沟壑区水肥因子对冬小麦经济性状的影响

利用田间试验方法,研究了不同水肥条件对冬小麦主要经济性状的影响．结果表明,限制黄土高原沟壑区冬小麦生产的最主要因素是肥而不是水．在任何灌水条件下,施肥对冬小麦的经济性状都有明显的正效应;而只有在施肥的条件下,灌水才有正效应;否则,灌水反而有负作用．     

不同灌水模式对冬小麦籽粒产量和水、氮利用效率的影响

在田间试验条件下,以冬小麦品种泰农18为材料,设置灌底墒水(CK)、底墒水+拔节水(W1)、底墒水+拔节水+越冬水与灌浆水交替灌溉(越冬/灌浆水交替灌溉模式,W2)、底墒水+拔节水+开花水(优化传统灌溉模式,W3)、底墒水+越冬水+拔节水+灌浆水(传统灌溉模式,W4)5种灌溉模式,每处理每次灌水量均为600 m3·hm-2,研究了山东泰安偏旱年份(2009-2010年)不同灌溉模式对小麦籽粒产量、水分利用效率和氮素利用效率的影响.结果表明:在小麦全生育期119.7 mm降水量条件下,越冬/灌浆水交替灌溉模式(W2)与传统灌溉模式(W4)籽粒产量差异不显著,但水分利用效率显著高于传统灌溉模式,与灌水量相同的优化传统灌溉模式(W3)相比,其小麦籽粒产量明显提高,水分利用效率无显著差异;越冬/灌浆水交替灌溉模式和传统灌溉模式的氮肥偏生产力最高,且籽粒收获后越冬/灌浆水交替灌溉模式在0 ～100 cm土层的硝态氮积累量显著高于传统灌溉模式和优化传统灌溉模式,降低了硝态氮的淋溶损失.在本试验条件下,越冬/灌浆水交替灌溉模式(W2)是可以兼顾小麦籽粒产量、水分利用效率和氮素利用效率的最佳灌溉模式.     

冬麦春播小麦穗分化阶段对低温胁迫的响应及耐寒性

以长江中下游地区引进的10个冬小麦品种为材料,在忻定盆地春播条件下,于2013-2014年研究了低温胁迫对冬小麦穗分化阶段光合作用、渗透调节物质及膜系统产生的影响,并对其抗寒性能进行综合评价.结果表明:在低温胁迫下,不同品种小麦叶片的离子渗漏率、可溶性糖和可溶性蛋白质含量均不同程度地升高,总叶绿素含量明显下降.通过主成分分析和抗寒性度量值(D值)排序,不同品种冬小麦幼穗分化期间的抗寒性为:渝麦10、扬麦20、云麦42的抗寒性较差;扬麦13、渝麦12、宁麦13的抗寒性较强且年际稳定性好,D值分别为0.665 ～0.659、0.493～0.495、0.471 ～0.583;而作为对照的宁2038、新春30分别为0.368～0.397、0.328～0.330.扬麦13、渝麦12、宁麦13的两年籽粒产量显著高于其他品种,可作为忻定盆地的引种材料.     

Relevance of physiological efficiency in wheat grain quality and the prospects of improvement

Released and pre-released bread wheat varieties evaluated in national wheat programme of India (503 genotypes) during 2005–14 under different environments were examined for the role of physiological parameters in grain quality. Genotypes with slow plant height growth but faster rate of grain filling enhanced protein content. Plants where growth in height and grain development was slow, grains were hard, provided proportionate vegetative growth phase is longer. Steady grain growth rate benefited gluten strength and gluten quality. Irrespective of total crop duration, longer reproductive phase was an effective indicator of higher flour recovery and test weight. Magnitude and significance of morphological attributes in grain quality was almost similar to that of physiological processes, therefore prospects of utilizing these field traits were examined to enhance grain properties. Early heading and longer grain filling was effective to increase test weight whereas delayed heading and shorter plant height enhanced protein content. Bold grains hampered grain hardness and delayed heading added more bran in the flour. Genotypes with poor grain bearing and quick grain ripening had lower sedimentation value. Instead of protein, it was wet gluten which expressed negative association with yield. To improvise gluten quality, extended reproductive phase but with less grain weight was helpful. Contribution of longer post-anthesis period was observed crucial in flour recovery. These useful simple field expressions can be deployed to uplift quality of wheat grains.     

苗期刈割伤害对春小麦影响的盆栽实验研究

盆栽实验研究了春小麦在苗期（三叶期）受到不同强度刈割伤害（模拟动物的采食）后的补偿作用。结果表明,在保持田间持水量６０％和９０％两种水分梯度下,春小麦苗期的刈割伤害均可刺激生长,出现生物产量和经济产量的超越补偿,而且受到重度刈割伤害春小麦（Ｅ、Ｆ）的补偿作用大于受到轻度刈割伤害春小麦（Ｂ、Ｄ）的补偿作用。这一超越补偿作用是以耗费较多的水分为基础的。     

Nitrogen fertiliser rate and post-anthesis waterlogging effects on carbohydrate and nitrogen dynamics in wheat

Waterlogging is predicted to increase in both magnitude and frequency along with global warming, and will become one of the most severe adversities for crop production in many regions. Nitrogen is considered to be an effective up-regulatory nutrient for crops grown under stress and non-stress conditions. In this study, we try to evaluate N fertiliser effects on contents of carbohydrate and N dynamics, dry matter accumulation in shoot, yield under post-anthesis waterlogging. Waterlogging after anthesis significantly reduced grain yield due to decrease in thousand-kernel-weight and in grain number per spike. High N fertiliser application aggravated grain yield loss due to post-anthesis waterlogging. These yield losses were related to the decreases in dry matter accumulation, redistribution of stored photosynthate to the grain, and the conversion capacity from carbohydrate to starch in grain. The decrease in dry matter accumulation could be attributed to the reduced activities of Pn (photosynthesis) and SPS (sucrose phosphate synthase) in the flag leaf, while the low capacity in starch synthesis could be explained by the reduced activities of sucrose synthase (SS) and soluble starch synthase (SSS) in grain. Total N uptake in shoot was also reduced, which could contribute to the losses in biomass and yield by waterlogging. The decrease in Pn was inconsistent with the increase in N content in the flag leaf at high N fertiliser application under post-anthesis waterlogging.     

Effects of abscisic acid (ABA) on grain filling processes in wheat

The effect of in situ water stress on the endogenous abscisic acid (ABA) content of the endosperm and the in vitro application of ABA on some important yield regulating processes in wheat have been studied. Water stress resulted in a marked increase in the ABA content of the endosperm at the time close to cessation of growth. Application of ABA to the culture medium of detached ears reduced grain weight. Exogenously applied ABA, at the highest concentration (0.1 mM) reduced transport of sucrose into the grains and lowered the starch synthesis ability of intact grains. In vitro sucrose uptake and conversion by isolated grains was stimulated by low ABA concentrations (0.001 mM) in the medium but was inhibited by higher concentrations. ABA application had no effect on sucrose synthase (SS) and uridine diphosphate glucose pyrophosphorylase (UDP-Gppase) activities, whereas adenosine diphosphate glucose pyrophosphorylase (ADP-Gppase), soluble starch synthase (SSS), and granule-bound starch synthase (GBSS) activities were reduced. These results raise the possibility that water stress-induced elevated levels of endogenous ABA contribute to reduced grain growth.     

苗期刈割伤害对春小麦生长及产量的影响

通过1996年大田试验研究了黄土高原半干旱区春小麦苗期（三叶－心期）受到不同强度刈割伤害（模拟动物的采食）后的补偿作用,结果,在大田试验条件下,受轻度刈割（刈割一半叶面积,H0,H1）,春小麦的补偿效应大于受重度刈割（刈割全部叶面积T0,T1）春小麦的补偿效应,且都低于未受刈割处理（对照,CK0,CK1）,即CK0＞H0＞T0;CK1＞H1＞T1,刈割处理后,灌溉一次水（CK1,H1,T1）虽可增强其补偿能力,促进小麦的生长,但仍为低补偿。