Application of natural plant extracts improves the tolerance against combined terminal heat and drought stresses in bread wheat

Drought and heat are among the main abiotic stresses causing severe damage to the cereal productivity when occur at reproductive stages. In this study, ten wheat cultivars were screened for combined heat and drought tolerance imposed at booting, heading, anthesis and post‐anthesis stages, and role of the foliage applied plant extracts was evaluated in improving the performance of differentially responding wheat cultivars under terminal heat and drought stresses. During both years, wheat crop was raised under ambient temperature and 70% water holding capacity (WHC) till leaf boot stage. The plant extracts (3% each) of sorghum, brassica, sunflower and moringa were foliage applied at booting, anthesis and post‐anthesis stage; and after one week of application of these plant extracts, combined heat and drought was imposed at each respective stage. Heat and drought stresses were imposed at each respective stage by placing pots in glass canopies with temperature of 4 ± 2°C above than the ambient temperature in combination with drought stress (35% WHC) until maturity. Combination of drought and heat stresses significantly reduced the performance of tested wheat cultivars; however, stress at the booting and heading stages was more damaging than the anthesis and post‐anthesis stages. Cultivars Mairaj‐2008 and Chakwal‐50 remained green with extended duration for grain filling, resulting in the maintenance of number of grains per spike and 100‐grain weight under stress conditions and thus had better grain yield and water‐use efficiency. However, in cultivars Fsd‐2008, and Shafaq‐2006, the combined imposition of drought and heat accelerated the grain filling rate with decrease in grain filling duration, grain weight and grain yield. Foliar application of all the plant extracts improved the wheat performance under terminal heat and drought stress; however, brassica extract was the most effective. This improvement in grain yield, water‐use efficiency and transpiration efficiency due to foliage applied plant extracts, under terminal heat and drought stress, was owing to better stay‐green character and accumulation of more soluble phenolics, which imparted stress tolerance as indicated by relatively stable grain weight and grain number. In crux, growing of stay‐green wheat cultivars with better grain filling and foliage application of plant extracts may help improving the performance of bread wheat under combined heat and drought stresses.     

公顷产10000kg小麦氮素和干物质积累与分配特性

以泰山23和济麦22为试验品种,通过连续2年的田间试验,对单产高达10 000 kg hm^-2的小麦进行了施氮量和氮素吸收转运和分配特性的研究。在2006-2007年生长季,随着施氮量的增加,小麦籽粒产量先增加后降低,施纯氮240 kg hm^-2 (N240)和270 kg hm^-2(N270)处理的产量分别达9 954.73 kg hm^-2和10 647.02 kg hm^-2,比不施氮肥处理(N0)分别增加11.20%和18.93%。与N0处理相比,施氮处理显著增加了小麦植株氮素积累量、籽粒氮素积累量和开花后营养器官氮素向籽粒的转运量;随着施氮量的增加,成熟期小麦植株氮素积累量呈先增后降趋势,以N270处理最高;开花后营养器官氮素向小麦籽粒转运量和转运率先升后降,转运量以N270处理最大,为213.78 kg hm^-2;而转运率以N240处理最高,为67.98%。随施氮量的增加,小麦成熟期各器官干物质积累量、花后营养器官干物质再分配量和再分配率先增后降,均以N270处理最高;开花后干物质积累对籽粒的贡献率亦呈先增后降的趋势,以N240处理最高。2005-2006年的试验结果呈相同变化趋势。在本试验条件下,小麦产量水平达10 000 kg hm^-2时的适宜施氮量为240~270 kg hm^-2,可供生产中参考。     

公顷产10000kg小麦氮素和干物质积累与分配特性

以泰山23和济麦22为试验品种,通过连续2年的田间试验,对单产高达10 000 kg hm^-2的小麦进行了施氮量和氮素吸收转运和分配特性的研究。在2006—2007年生长季,随着施氮量的增加,小麦籽粒产量先增加后降低,施纯氮240 kg hm^-2 (N240)和270 kg hm^-2(N270)处理的产量分别达9 954.73 kg hm^-2和10 647.02 kg hm^-2,比不施氮肥处理(N0)分别增加11.20%和18.93%。与N0处理相比,施氮处理显著增加了小麦植株氮素积累量、籽粒氮素积累量和开花后营养器官氮素向籽粒的转运量;随着施氮量的增加,成熟期小麦植株氮素积累量呈先增后降趋势,以N270处理最高;开花后营养器官氮素向小麦籽粒转运量和转运率先升后降,转运量以N270处理最大,为213.78 kg hm^-2;而转运率以N240处理最高,为67.98%。随施氮量的增加,小麦成熟期各器官干物质积累量、花后营养器官干物质再分配量和再分配率先增后降,均以N270处理最高;开花后干物质积累对籽粒的贡献率亦呈先增后降的趋势,以N240处理最高。2005—2006年的试验结果呈相同变化趋势。在本试验条件下,小麦产量水平达10 000 kg hm^-2时的适宜施氮量为240~270 kg hm^-2,可供生产中参考。     

Nitrogen Accumulation and Translocation for Winter Wheat under Different Irrigation Regimes

The translocation of pre‐anthesis nitrogen to the grain is an important source for winter wheat. The relation between the nitrogen translocation and irrigation regime was studied in the field under a rain‐proof trough shelter. Nitrogen (N) translocation amount, N translocation efficiency decreased with a decline in irrigation amount or by excessive irrigation. Compared with different organs, the leaf and stem had higher N translocation amounts, and contributions to grain for both cultivars – Jinan 17 and Lumai 21, indicating that stem also is a major N source for grain development. The contribution of pre‐anthesis total above ground N to grain N ranged from 57 to 76 %, indicating the importance of pre‐anthesis storage of N for achieving high grain N concentrations. Grain nitrogen and yield (kg ha^?1) were positively and significantly correlated with the N translocation amounts and contributions, respectively, suggesting that the sink strength may be involved in the translocation of N from a vegetative organ to the grain. N harvest index (NHI) was significantly correlated with N translocation efficiency, suggesting that the latter is a prerequisite for increasing grain N and improving grain quality. The experiment showed that N translocation status is enhanced by better irrigation practices, but limited by severely deficient or excessive irrigation.     

稻茬小麦公顷产量9000 kg群体钾素积累、分配与利用特性

在稻麦两熟制条件下,以扬麦20为材料,通过基本苗和氮肥施用量、施用时期及比例的调控,建立不同产量水平群体,研究籽粒产量9000 kg hm^-2群体钾素积累、分配与利用特性。结果表明,籽粒产量≥9000 kg hm^-2 (超高产)群体钾素吸收高峰期出现在拔节至开花期,吸收的钾素占一生吸收钾素的52%~68%;开花期和成熟期钾素积累量均极显著高于<9000 kg hm^-2 (高产)群体。成熟期叶片、茎鞘、颖壳+穗轴和籽粒钾素积累量与籽粒产量均呈极显著线性正相关;花后茎鞘钾素转运量与产量呈极显著线性正相关,颖壳+穗轴钾素转运量与产量呈极显著线性负相关。超高产群体开花期和成熟期钾素积累量分别为430~450 kg hm^-2和366~408 kg hm^-2;成熟期钾素积累量,茎鞘中最高,为244~269 kg hm^-2,其次是叶片和颖壳+穗轴,分别为46~49 kg hm^-2和40~46 kg hm^-2,籽粒中仅为35~46 kg hm^-2;花后茎鞘钾素转出量为46~52 kg hm^-2,颖壳+穗轴钾素积累量为9~17 kg hm^-2。超高产群体每100 kg籽粒的吸钾量需达4.57~4.87 kg,此时的钾素利用效率为20.56~22.02 kg kg^-1,钾收获指数为0.095~0.112。     

Crop and Weed Growth in a Sequence of Spring Barley and Winter Wheat Crops Established Together from a Spring Sowing (Relay Cropping)

A relay cropping system of cereals, whereby winter wheat (Triticum aestivum L.) was undersown in two‐row spring barley (Hordeum distichum L.), was established in a field trial in central Sweden in 1999 and continued until 2000. The purpose of the study was to examine crop and weed responses to different plant densities of the undersown winter crop. Winter wheat was sown at four seed rates (187, 94, 47 and 0 kg ha^?1) immediately after the sowing of barley. Barley was harvested in the first autumn after sowing and winter wheat in the second autumn. The grain yield of barley was not affected by the seed rate of wheat, and averaged 4580 kg ha^?1. Winter wheat did not vernalize during the first growing season but remained at the vegetative stage. The grain yield of wheat was 1990 kg ha^?1 for the lowest and 5610 kg ha^?1 for the highest seed rate of wheat. Whilst the undersowing process itself stimulated weed emergence in this experiment, increasing the undersowing seed rate reduced the population of perennial weeds by 40–70 %. In the second growing season, the total biomass of weeds was 66 % higher at the highest seed rate compared with the lowest seed rate.     

Winter Wheat Cultivar Responses to Fungicide Application are Affected by Nitrogen Fertilization Rate

Foliar fungicides are important management inputs for winter wheat (Triticum aestivum L.) in high-yielding areas of Europe, but their effectiveness may interact with cultivar selection and nitrogen (N) fertilization. No information is available on the potential use of fungicides in reducing yield losses from foliar diseases in Croatia, where wheat crop is extensively grown under low N inputs. Field experiments were conducted during 2000–02 to evaluate the agronomic responses of six winter wheat cultivars to fungicide application (tebuconazol around heading) compared with untreated plots at low (67 kg N ha⁻¹) and high (194 kg N ha⁻¹) N fertilization rates. Grain yields tended to increase in all years following fungicide treatment at high N rate by an average of 10.1 % (773 kg ha⁻¹), but improved significantly in one year only at low N rate. When these occurred, yield increases were associated with larger grain weight per ear primarily due to heavier 1000-kernel weight. Cultivars differed in their responses to fungicide application across growing seasons and N fertilization rates. Under low disease pressure in 2000 and 2001, improved yields with fungicide use occurred for few susceptible cultivars only, whereas all cultivars significantly increased yields under higher disease severity in 2002 by an average of 383 kg ha⁻¹ (5.0 %) at low N rate and 1443 kg ha⁻¹ (19.0 %) at high N rate. Following fungicide application at high N rate, some susceptible cultivars outyielded resistant cultivars, whereas opposite responses occurred in untreated plots. High N fertilization rate consistently produced larger grain yields except under high disease severity and no fungicide sprayed in 2002, when it had no benefits at all over low N rate. Fungicide application showed limited importance for wheat performance at low N rate; however, cultivars significantly differed in yield responses as well as in rankings after fungicide use at high N fertilization rate.     

Strategies to Improve the Use Efficiency of Mineral Fertilizer Nitrogen Applied to Winter Wheat

Recovery of fertilizer nitrogen (N) applied to winter wheat crops at tillering in spring is lower than that of N applied at later growth stages because of higher losses and immobilization of N. Two strategies to reduce early N losses and N immobilization and to increase N availability for winter wheat, which should result in an improved N use efficiency (= higher N uptake and/or increased yield per unit fertilizer N), were evaluated. First, 16 winter wheat trials (eight sites in each of 1996 and 1997) were conducted to investigate the effects of reduced and increased N application rates at tillering and stem elongation, respectively, on yield and N uptake of grain. In treatment 90‐70‐60 (90 kg N ha^?1 at tillering, 70 kg N ha^?1 at stem elongation and 60 kg N ha^?1 at ear emergence), the average values for grain yield and grain N removal were up to 3.1 and 5.0 % higher than in treatment 120‐40‐60, reflecting conventional fertilizer practice. Higher grain N removal for the treatment with reduced N rates at tillering, 90‐70‐60, was attributed to lower N immobilization (and N losses), which increased fertilizer N availability. Secondly, as microorganisms prefer NH₄⁺ to NO₃^? for N immobilization, higher net N immobilization would be expected after application of the ammonium‐N form. In a pot experiment, net N immobilization was higher and dry matter yields and crop N contents at harvest were lower with ammonium (ammonium sulphate + nitrification inhibitor Dicyandiamide) than with nitrate (calcium nitrate) nutrition. Five field trials were then conducted to compare calcium nitrate (CN) and calcium ammonium nitrate (CAN) nutrition at tillering, followed by two CAN applications for both treatments. At harvest, crop N and grain yield were higher in the CN than in the CAN treatment at each N supply level. In conclusion, fertilizer N use efficiency in winter wheat can be improved if N availability to the crops is increased as a result of reduced N immobilization (and N losses) early in the growth period. N application systems could be modified towards strategies with lower N applications at tillering compensated by higher N dressing applications later. An additional advantage is expected to result from use of nitrate‐N fertilizers at tillering.     

不同灌水处理对强筋小麦籽粒产量和蛋白质组分含量的影响

在小麦全生育期降水47.9 mm的条件下,对7个强筋小麦品种,采用二因素裂区设计,研究了不同灌水处理对籽粒产量、蛋白质组分和沉降值的影响。结果表明,籽粒产量和千粒重均以春季灌3水(春2叶露尖、春5叶露尖和开花期分别灌水40 m³)处理最高,与灌1水（春5叶露尖灌水40 m³）处理差异显著。烟农19的产量最高,与其他品种差异显著。不同灌水处理对醇溶蛋白含量的影响较大,以灌3水处理最高,与灌1水和2水（春5叶露尖和开花期分别灌水40 m³）处理差异显著。不同品种各蛋白质组分差异均显著,品种间谷蛋白含量的变异系数最大。不同品种在不同灌水条件下均表现为谷蛋白含量>醇溶蛋白>清蛋白>球蛋白,其比例约为3.6∶2.7∶1.7∶1。不同灌水处理间沉降值差异不显著,品种间差异极显著。综合考虑小麦产量和品质,在本试验条件下,以春季灌3次水为宜。     

麦季氮肥运筹对冬小麦–夏玉米种植体系物质生产及氮肥利用的影响

2009-2011年在山东临沂冬小麦-夏玉米生产田,探讨了麦季施氮水平和施氮时期对两季作物干物质积累与分配、籽粒产量、氮肥农学利用率和氮肥偏生产力的影响。施氮量设4个处理,分别是0 (N0)、168.75 (N1)、225 (N2)和281.25 kg hm^-2 (N3);氮肥追施时期设2个处理,分别为拔节期(S1)和拔节期+开花期(S2)。在S1条件下,冬小麦和夏玉米的籽粒干物质积累量及夏玉米和周年生物产量均表现为N3>N2>N1,冬小麦和夏玉米的籽粒产量N2和N3处理间无显著差异;氮肥农学利用率和氮肥偏生产力在麦季随施氮量增加显著降低,而在玉米季则逐渐升高,但玉米季氮肥偏生产力N3与N2处理间无显著差异。S2条件下麦季施氮量由N2处理增加25% (N3),冬小麦和夏玉米籽粒干物质积累量、生物产量和籽粒产量无显著变化,氮肥农学利用率和氮肥偏生产力在麦季显著降低、在玉米季无显著变化。与S1相比,S2有利于提高N1和N2条件下冬小麦籽粒与营养器官的干物质积累量、生物产量、籽粒产量和氮肥农学利用率及氮肥偏生产力,但对N3条件下的这些指标无显著影响;而在玉米季,3个施氮量水平下夏玉米的各项指标均显著升高。综合周年生物产量、籽粒产量和氮肥农学利用率及氮肥偏生产力结果,麦季总施氮量225 kg hm^-2及拔节期+开花期追氮是本试验条件和种植模式下的最佳麦季氮肥运筹模式。     

冬小麦-夏玉米“双晚”种植模式的产量形成及资源效率研究

为了进一步明确黄淮平原冬小麦晚播、夏玉米晚收的“双晚”增产及资源高效的效应,选用2个中熟冬小麦品种和2个中晚熟夏玉米品种,于2006—2008年先后在河南温县和焦作进行大田试验,研究作物群体物质生产、产量形成参数定量指标及光温资源的分配利用。结果表明,冬小麦晚播产量降低不明显,夏玉米晚收产量显著提高747~2 700 kg hm^-2,“双晚”周年产量21 891~22 507 kg hm^-2,比对照提高442~2 575 kg hm^-2。冬小麦晚播平均叶面积指数、每平方米穗数和穗粒数降低,但平均净同化率、收获指数和粒重提高达5%显著水平;夏玉米晚收平均叶面积指数、收获指数、生育期天数和粒重均显著提高。“双晚”栽培优化了周年资源分配,提高生育期与光、温资源变化的吻合度,其生产效率分别提高2.22%~10.86%和0.47%~11.56%。小麦和玉米品种的遗传类型是影响“双晚”栽培技术的关键。因此,选用小麦晚播早熟高产和玉米长生育期晚熟品种,通过有效调节资源配置,将小麦冗余的光温资源分配给C₄高光效作物玉米,是提高周年高产高效的重要途径。     

不同施氮水平对超高产夏玉米氮磷钾积累与分配的影响

为探明不同施氮水平下玉米超高产(≥13 500 kg hm^-2)群体氮磷钾积累及分配规律,通过苏玉20、浚单20两品种3年不同氮肥运筹方案的试验,实现了籽粒最高产量14 753 kg hm^-2的目标。结果表明：(1)随着生育进程,两品种氮磷钾在植株、籽粒中积累逐渐增大,在叶片、茎秆、叶鞘中呈先单峰变化趋势,叶片氮钾峰值在大口期,磷峰值在开花期。增大灌浆期植株氮积累量及叶片氮转移率,促使成熟期籽粒氮磷较大积累量,利于超高产玉米群体的形成。(2)籽粒产量、1 kg氮生产籽粒量、氮肥的农学效率、氮素利用率、植株(及叶片、茎秆、叶鞘、籽粒等器官)氮磷钾含量在450 kg hm^-2施氮水平时达到最大值,其值(苏玉20)分别为14753 kg hm^-2、44.0 kg、19.24%、38.63%、335.4 kg hm^-2、178.2 kg hm^-2、230.7 kg hm^-2,过高过低施氮均使氮磷钾积累量及产量下降。(3)由两品种产量与施氮水平的回归方程,确定了超高产时的最佳施氮量、超高产施氮水平和最佳施氮范围,苏玉20分别为457.0 kg hm^-2、418.3~495.7 kg hm^-2、418.5~495.4 kg hm^-2;浚单20分别为452.7 kg hm^-2(最佳施氮量)、410.8~494.6 kg hm^-2 (最佳施氮范围)。     

稻–麦轮作下9000kg hm~(–2)产量水平扬麦20的群体质量及花后光合特征

在稻麦两熟制条件下,于2010—2011和2011—2012年度,通过氮肥施用量、施用时期及比例的调控,建立了扬麦20不同产量水平群体,比较≥9000 kg hm–2群体(P1)与9000 kg hm–2群体(P2)的产量构成、群体质量及花后光合特征,为稻茬小麦大面积高产提供理论依据和技术支撑。P1较P2群体产量高约10%,每穗粒数高约5.5%,差异显著,但两群体的穗数和千粒重差异不显著。P1群体的穗数、穗粒数和千粒重分别为482~538万hm–2、47~49粒和34~39 g。籽粒产量与孕穗和开花期叶面积指数(LAI)及花后LAI衰减率和光合势呈抛物线关系,与乳熟期LAI、粒(重)/叶比和群体生长率呈显著线性正相关。两年度试验结果表明P1群体具有以下特征,孕穗期、开花期和乳熟期的LAI分别为6.5~7.0、5.0~6.0和4.0~4.5;粒(数)/叶比为0.37~0.39,粒(重)/叶比为13.5~14.5;花后LAI衰减率、群体生长率、光合势和净同化率分别为0.13~0.15 d–1、19~20 g m–2 d–1、103×104~118×104 m2 d hm–2和9~11 g m–2 d–1。花后21d和28 d,剑叶SPAD值、净光合速率、丙二醛(MDA)含量及3种抗氧化酶(CAT、POD和SOD)活性与产量相关性均达极显著水平。研究表明,稻–麦轮作体系中,扬麦20达到9000 kg hm–2产量水平的栽培技术关键点是获得适宜穗数的基础上,主攻每穗粒数与千粒重的协调增加,使群体在花前具有较高的光合面积和光合速率,花后光合面积衰减速率低,维持较高的光合面积,从而充分积累花后光合物质,在适宜库容基础上保障对库充实的需求。     

冀东冬小麦灌浆期与千粒重的试验研究

通过对195份冬小麦资源品种（系）的抽穗期、灌浆时间与千粒重的试验分析表明；冀东冬小麦的抽穗期主要在5月1－14日，而5月7－12日是抽穗的高峰期，达到总量的80．4％；灌浆时间在35－45d之间，以37－41d的品种最多，占品种总数的88．2％。随抽穗的推迟、灌浆期的缩短，千粒重呈显著下降趋势，相关系数分别为r=-0.4365和r=0.8924.     

Effect of tire rubber ash and zinc sulfate on yield and grain zinc and cadmium concentrations of different zinc-deficiency tolerance wheat cultivars under field conditions

The aims of these field experiments were to investigate the effectiveness of soil application of rubber tire ash in comparison with soil and foliar applications of zinc (Zn) sulfate to increase Zn and decrease cadmium (Cd) concentrations in wheat grain. A two-year field experiment was conducted during the 2007–2008 and 2007–2008 growing seasons at Isfahan research field, Iran. Ten different Zn-efficiency bread wheat cultivars (Triticum aestivum L.) commonly cultivated in different parts of Iran were subjected to no Zn fertilizer addition (control), soil application of 40 kg ha⁻¹ ZnSO₄, soil application of 100 (for the first year) and 250 (for the second year) kg ha⁻¹ waste rubber tire ash, foliar application of Zn at the mid tillering stage, and foliar application of Zn at the early anthesis stage. In the foliar application, ZnSO₄ was sprayed at a rate of 0.66 kg Zn/ha. Foliar spray of zinc sulfate at early anthesis, in general, had no significant effect on the yield and grain Cd while significantly increased grain Zn concentrations of most cultivars. On average, the foliar Zn treatment at the mid tillering stage (0.66 kg Zn/ha), decreased the mean grain Cd concentration from 0.032 mg kg⁻¹ in the control treatment to 0.024 mg kg⁻¹. While the grain Zn concentrations of some cultivars increased with soil application of Zn sulfate, they were not affected or even decreased in other cultivars. For most studied wheat cultivars, pre-planting application of rubber tire ash in soil resulted in a significant decrease of grain Cd concentrations. The results show that the effectiveness of soil and foliar application of Zn on yield and grain Zn and Cd concentrations greatly depends on the cultivar. The currently recommended rates of soil applications of Zn to ameliorate Zn deficiency are sufficient to increase grain Zn and decrease grain Cd concentrations in some wheat cultivars, while they do not in the others. In this study, soil application of 250 kg rubber tire ash/ha and foliar spray of 0.66 kg Zn/ha at tillering stage were the most effective treatments to ameliorate Zn deficiency and to increase Zn and decrease Cd concentration in grains of most wheat cultivars.     

长江中下游小麦品种根系改良特征及其与产量的关系

为探明小麦品种更替过程中根系改良特征对氮肥的响应及其与产量形成的关系,从而为高产品种选育及根冠构型建成提供理论依据。本研究以长江中下游不同年代大面积推广的代表性小麦品种南大2419、扬麦1号、扬麦158和扬麦16为材料,采用大田和盆栽试验,研究了3个施氮水平(纯氮0、225和300 kg hm–2)下小麦根系形态与生理特性的差异及其与产量的关系。结果表明,小麦籽粒产量随品种育成年代推进逐步增加,现代品种对施氮的响应较早期品种大。现代小麦品种拔节至开花阶段根系干物质积累量和生长速率显著高于早期品种,而播种至拔节期早期品种的根系生长在无氮条件下具有较强的生长优势。小麦根系总根长、表面积、根体积、0~60 cm土层根重密度、根系活力和SOD活性随品种育成年代逐步提高,而MDA含量显著降低。增施氮肥促进了不同年代品种根系生长,但现代品种增幅较早期品种大,说明品种改良提高了小麦根系对氮肥的响应。籽粒产量与开花期根系总根长、表面积、根系生物量和0~60 cm根重密度呈显著正相关。因此,增加根系与土壤接触面积和高氮适应性、提高根系生理活性、延缓根系衰老是长江中下游小麦品种演变的重要特征也是高产高效栽培调控的重要目标。     

不同土层测墒补灌对小麦旗叶光合特性和干物质积累与分配的影响

2011-2012和2012-2013年连续2个小麦生长季,在大田条件下,设置0~20 cm (D1)、0~40 cm (D2)、0~60 cm (D3)和0~140 cm (D4) 4个土层测定土壤含水量,以各土层平均土壤相对含水量拔节期65%和开花期70%为目标相对含水量,全生育期不灌溉为对照处理 (D0),研究依据不同土层的土壤含水量测墒补灌对小麦旗叶光合特性和干物质积累与分配的影响。结果表明：D2的开花期叶面积指数和单位土地面积上旗叶叶面积、开花后7 d和14 d的旗叶净光合速率和实际光化学效率均高于其他处理,而气孔限制值低于其他处理;D2的成熟期干物质积累量、开花后干物质向籽粒的分配量和开花后同化物分配对籽粒的贡献率亦高于其他处理。两年度D2的籽粒产量分别为9367.4 kg hm^-2和9727.5 kg hm^-2,均显著高于其他处理;同时,D2的水分利用效率高于D0、D3和D4处理,与D1处理无显著差异。因此,于小麦拔节期和开花期依据0~40 cm土层的土壤含水量测墒补灌是同步实现高产和高水分利用效率的有效措施。     

Agronomic performance of winter wheat grown under highly divergent soil moisture conditions in rainfed and water‐managed environments

Even in the temperate climates of Europe, increasing early season drought and rising air temperature are presenting new challenges to farmers and wheat breeders. Sixteen winter wheat (Triticum aestivum L.) genotypes consisting of three hybrids, six line cultivars and two breeding lines from Germany as well as five line cultivars from France, Austria, Slovakia, Hungary and the Ukraine (referred to as “exotic” lines) have been included in this study. The genetic materials were evaluated over three growing seasons under a range of soil moisture regimes at the three North German sites Braunschweig (irrigated and drought‐stressed), Warmse (rainfed) and Söllingen (rainfed). The average grain yields in the twelve growth environments (water regime × season combinations) ranged from 6.1 to 13.5 t ha^?1. The exotic lines showed little evidence of specific phenological adaptation to drought although they are frequently faced with water scarcity in their countries of origin. The hybrids and German lines exhibited higher regression coefficients (b_i) to environmental means than the exotic lines, indicating particular adaptation to favourable growing conditions. The phenotypical correlations of grain yield between the various environments were high, ranging for instance from 0.6 to 0.8 for the irrigated and drought‐stressed environments at Braunschweig. It is thus expected that in the foreseeable future continued selection aiming at high yield potential will suffice as a means to counter the expected increase in droughts.     

Transfer of Grain Legume Nitrogen within a Crop Rotation Containing Winter Wheat and Winter Barley

In a crop rotation trial, conducted from 1985 to 1988 at TU-Munich's research station in Roggenstein, the transfer of grain legume nitrogen was evaluated in crop rotations containing fababeans and dry peas as well as oats (reference crop) and winter wheat and winter barley as following crops. The results obtained can be summarized as follows: Dinitrogen fixation by fababeans ranged from 165 to 240 kg N ha¹, whereas N₂-fixation by peas amounted from 215 to 246 kg N ha^?1. In all seasons the calculated N-balance where only grain was removed was positive, with a net gain being on average 106 (peas) and 84 (fababeans) kg N ha^?1. After the harvest of peas 202 kg N ha^?1 remained on the field on average over seasons (158 kg N ha^?1 in the above ground biomass and 44 kg N ha^?1 as NO₃-N in 0–90 cm depth). As compared to peas, fababeans left 41 kg N ha^?1 less due to smaller amounts of nitrogen in the straw. After oats very small amounts of residual nitrogen (33 kg N ha^?1) were detected. After the harvest of grain legumes always a very high nitrogen mineralization was observed during autumn especially after peas due to a close C/N-relationship and higher amounts of nitrogen in the straw as compared to fababeans. In comparison with fababeans, N-mineralization after the cultivation of oats remained lower by more than 50%. During winter, seepage water regularly led to a considerable decrease of soil NO₃-N content. The N-leaching losses were especially high after cultivation of peas (80 kg N ha ^?1) and considerably lower after fababeans (50 kg N ha^?1) and oats (20 kg N ha^?1). As compared to oats, a higher NO₃-N content in soil was determined at the beginning of the growing period after preceding grain legumes. Therefore, winter wheat yielded highest after preceding peas (68 dt ha^?1) and fababeans (60 dt ha^?1) and lowest after preceding oats (42 dt ha^?1). The cultivation of grain legumes had no measurable effect on yield formation of the third crop winter barley in either of the growing seasons.     

Analysis of Water Non-limiting and Water Limiting Yields and Yield Gaps of Groundnut in India Using CROPGRO-Peanut Model

To assess the scope for enhancing productivity of groundnut (Arachis hypogaea L.) in India, well‐calibrated and validated CROPGRO‐Peanut model was used to assess potential yields (water non‐limiting and water limiting) and yield gaps of groundnut for 18 locations representing major groundnut growing regions of India. The average simulated water non‐limiting pod yield of groundnut for the locations was 5440 kg ha^?1, whereas the water limiting yield was 2750 kg ha^?1 indicating a 49 % reduction in yield because of deficit soil moisture conditions. As against this, the actual pod yields of the locations averaged 1020 kg ha^?1, which was 4420 and 1730 kg ha^?1 less than the simulated water non‐limiting and water limiting yields, respectively. Across locations, the simulated water non‐limiting yields were less variable than water limited and actual yields, and strongly correlated with solar radiation during the crop season (R² = 0.62, P ≤ 0.01). Simulated water limiting yield showed a significant positive, but curvilinear relationship (R² = 0.73, P ≤ 0.01) with mean crop season rainfall across locations. The relationship between actual yield and the mean crop season rainfall across locations was not significant, whereas across seasons for some of the locations, the association was found to be significant. Total yield gap (water non‐limiting minus actual yields) ranged from 3100 to 5570 kg ha^?1, and remained more or less unaffected by the quantity of rainfall received across locations. The gap between simulated water non‐limiting and water limiting yields, which ranged from 710 to 5430 kg ha^?1, was large at locations with low crop season rainfall, and narrowed down at locations with increasing quantum of crop season rainfall. On the other hand, the gap between simulated water limiting yield and actual farmers yield ranged from 0 to 3150 kg ha^?1. It was narrow at locations with low crop season rainfall and increased considerably at locations with increasing amounts of rainfall indicating that type of interventions to abridge the yield gap will vary with the rainfall regimes. It is suggested that improved agronomic management (such as high yielding cultivars, balance crop nutrition and control of pest and diseases) in high rainfall regimes and rainfall conservation and supplemental irrigations in low rainfall regimes will be essential components of the improved technologies aimed at abridging the yield gaps of groundnut.