Selection for biomass yield in wheat

Summary Biomass (above ground plant parts) yield may be a useful selection trait for yield improvement in wheat (Triticum aestivum L.). This study was conducted to estimate realized heritability of biomass yield and to determine the response to selection for high and low biomass yield in 8 genetically diverse populations of spring wheat under two production systems. Selections were made among the F₃ lines. Progenies of the selected lines were evaluated in replicated field tests in the F₄ generation under high fertility and low fertility production systems at Rampur, Nepal, in 1991. Fertility level had a significant effect on biomass yield, grain yield, effective tiller number, number of kernels per spike, thousand kernel weight, and harvest index. Selection in the F₃ for high and low biomass yield was effective in identifying F₄ lines with high and low biomass yield, respectively. Biomass yield differences between high and low selection groups in the F₄ generation, expressed as percent of the mean of the low selection group and averaged over the eight populations, were 53.9 and 36.5% higher than the mean of the low selection group under the high and the low fertility production systems, respectively. The corresponding figures for grain yield were 48.8 and 34.9% under the high and the low production systems, respectively. Also, selection for high biomass yield resulted in higher effective tiller number, and number of kernels per spike, but lower harvest index. Realized heritability estimates for biomass yield were greater at high fertility (range 0.49 to 0.85) than at low fertility (range 0.22 to 0.44). Biomass yield showed positive genotypic correlations with grain yield, effective tiller number, and number of kernels per spike but a negative correlation with harvest index. The results indicated that selection for high biomass yield should bring about positive improvements in biomass yield, grain yield, effective tiller number, and number of kernels per spike. The correlation between F₃ and F₄ generations suggested that biomass yield in the F₃ generation was a good predictor of biomass yield and grain yield in the F₄ generation. Selection for biomass yield in wheat should be made under the standard production system to obtain a realistic response.     

Ear:stem ratios in breeding populations of wheat: significance for yield improvement

Earlier studies showed that the ratio of the weight of the wheat ear to stem at anthesis (ear:stem ratio) may give a better indication of potential yield than harvest index because it is determined early in the life cycle and is not affected by post anthesis stress. These studies concluded that selection for high ear:stem ratio at anthesis may lead to further improvement in grain yield of wheat. The present work was undertaken in the field to identify lines varying in ear:stem ratio in breeding populations and to study its implications for yield improvement.At anthesis stem length, ear length, tiller number, dry weight of stem and ear and ear:stem ratio were measured in 14 crosses on F₂ single plants and F₂ derived lines grown in the F₃, F₄, and F₅ at three locations in Western Australia over four seasons. In addition, biomass, grain yield and yield components were measured on selected crosses at two locations on F₂ derived lines grown in the F₄ and F₅. There was a considerable range of ear:stem ratio between and within the crosses studied. Although ear:stem ratio was strongly correlated with stem length, there was substantial variation within stem length classes. Ear:stem ratio had a high mean broad sense heritability (82%), whereas HI, grain yield and above ground biomass had lower heritabilities, 68, 55 and 35% respectively. Ear:stem ratio was strongly correlated between generations and sites indicating stability of this character. Ear:stem ratio had a significant positive correlation with grain yield, HI, grains per ear and per m². The correlation of grain yield with HI was equal or slightly higher than that of grain yield with ear:stem ratio.Ear:stem ratio offers promise as a predictor of HI and yield potential where post-anthesis moisture stress can influence HI. Ear:stem ratio measurement is unlikely to be adopted for selection purposes in routine breeding programs, as it is laborious and time consuming. However, ear:stem ratio could be used to identify superior parental genotypes and early generation selections from special crosses in terms of its ability to partition assimilate.     

大豆不同产量水平生物量积累与分配的动态分析

利用亲本间生物量、产量有较大差异的重组自交家系群体(NJRIKY),在相对控制遗传背景的条件下研究地下和地上部生物量与产量相关的动态,比较高中低产家系生物量累积和分配的动态特征,为大豆高产栽培管理和育种提供生物量动态调控与选择的依据。结果表明: (1) 地下部和地上部生物量与产量显著相关,随生长进程,相关系数逐渐增加,至鼓粒期(R5~R6期)相关系数达到最大,r分别约0.76和0.79;(2) 大田条件2 500~2 800 kg hm^-2以上的高产家系,地下部和地上部生物量显著高于中、低产家系,最大累积值均出现在鼓粒期,地下部和地上部生物量最大值分别为660~700 kg hm^-2和7 200~7 800 kg hm^-2。(3) 两年高产组所包含的家系不尽相同,产量下降的家系相应生物量也下降,这归因于环境所致的生物量累积不足;(4) 高产家系各器官生物量分配动态特征为茎秆、叶柄占同时期全生物量的比例显著高于中、低产家系,R5时分别为30.8%和10.6%,而叶、根比例显著低于中、低产家系,R5时分别为34.1%和9.7%。未来大豆产量的突破有赖于品种生物量与收获指数的综合改良和生长调控技术的继续改进。     

低氮密植栽培对超级稻产量和氮素利用率的影响

为了研究低氮密植栽培对水稻分蘖发生及成穗率、干物质积累及其转化、氮素利用率和产量的影响,2012—2013年以超级稻Y两优1号为材料,在湖南长沙和海南澄迈进行了施氮量(75、150、225 kg N hm–2)与栽插密度(68、40、27、19穴m–2),每穴苗数(单、双、三本穴–1)与栽插密度(40、27、19、14穴m–2)的大田栽培试验。结果表明,在基本苗数相同或相近的条件下,减苗增密在齐穗期和成熟期的干物质量及产量分别比增苗减密高10.5%、5.2%和2.9%,有效穗数对产量的贡献最大,达到显著水平;在低氮密植条件下,有效分蘖期缩短6 d左右,分蘖成穗率、表观转化率、氮肥偏生产力和氮素籽粒生产效率分别提高10.9%、21.0%、150.6%和19.6%。在施氮量为75 kg N hm–2的密植(40~68穴m–2)条件下,齐穗期和成熟期的干物质量及长沙点产量分别比中、高氮(150~225 kg N hm–2)常规密度(19~27穴m–2)低3.2%、7.5%和1.2%,但差异不显著,而澄迈点产量在2012年和2013年分别比之低5.2%和高9.1%,且差异均达显著水平。在施氮量为150 kg N hm–2的密植条件下,成熟期干物质量比高氮常规密度低1.7%,但齐穗期干物质量和产量比高氮常规密度高10.3%和3.3%。因此,超级稻采用低氮密植栽培,在100~150 kg N hm–2和40穴m–2条件下提早了够苗期,增加了有效穗数,提高了分蘖成穗率和结实率,加之齐穗期适宜的干物质积累和较高的表观转化率,有利于高产的形成和氮肥利用率的提高。     

Impact of Nitrogen and Plant Growth Promoting Rhizobacteria on yield and yield components of sunflower in a glasshouse environment

The effects of Nitrogen (N) and Plant Growth Promoting Rhizobacteria (PGPR) on growth and development of sunflower (Helianthus annuus L. var. Hysun-33) grown in the greenhouse under a natural environment were studied. The N-use efficiency of a sunflower crop grown under three N rates (N₁ = 0 kg ha^?1, N₂ = 120 kg ha^?1, and N₃ = 240 kg ha^?1) and three PGPR levels (R₁ = 0 kg ha^?1, R₂ = 30 kg ha^?1, and R₃ = 60 kg ha^?1) were investigated. The maximum amount of N resulted in higher total dry matter production per plant and the effect was prominent from 34 days after sowing (DAS). Seed yields differed significantly among different sunflower crops especially at limiting N supply, with significant shifts according to the N level. N uptake was an important parameter for yield at all N rates. The 240 kg N ha^?1 treatments provided the maximum yield, while the oil contents in these treatments of higher yield showed a lower oil content (%). Harvest index was also significantly correlated to yield across N rates; however, its importance depended much on environmental conditions as well. It can be inferred from the study that sunflower crop is well-supplied with respect to growth, development, yield and yield components, to enhance N efficiency and depends very much on the N supply. All the parameters gave maximum results with the increment of N while PGPR regimes had no prominent impact on the sunflower crop, the target environment, and the target yield level grown under a specified controlled glasshouse environment.     

机插条件下低氮密植栽培对“早晚兼用”双季稻产量和氮素吸收利用的影响

为了缓解长江中下游双季稻区机插双季稻生育期不配套的矛盾,2014—2015年早晚两季均以常规早稻品种中嘉早17为材料,在大田栽培条件下研究机插密度(36.4、28.6、19.0穴m–2)与施氮量(0、110~140、176~189 kg N hm–2)对机插双季稻产量及氮肥利用率的影响。结果表明:采用"早晚兼用"机插双季稻栽培模式有利于早、晚2季周年高产,以"高密+高氮"处理产量最高,2年分别达到16.94 t hm–2和16.99 t hm–2,但与"高密+低氮"处理的产量差异不显著;氮肥利用率随氮肥用量增加而下降,随栽插密度增加而提高,以"高密+低氮"处理最高,2年4季分别为62.77%、55.75%、65.82%、64.37%,比"高密+高氮"处理分别提高12.11%、9.01%、8.49%、2.14%;"高密+低氮"处理与"低密+高氮"处理相比,群体干物质积累量及辐射利用率均有一定的优势。由此可见,在此模式下适当增加机插密度,减少氮肥用量,既可实现高产,又能显著提高氮素利用率。采用"早晚兼用"品种搭配模式,低氮、密植栽培可作为长江中下游双季稻区机插双季稻生产的关键技术。     

氮肥用量及钾肥施用对稻麦周年产量及效益的影响

为探明优化施氮量与高施氮量下不同钾肥施用处理对稻麦周年产量及效益的影响。本试验于2010年5月–2011年7月在江苏省如皋市农业科学研究所试验基地的田间稻麦轮作条件下,对常规粳稻品种镇稻11和春性中筋品种扬麦16设置了两个氮肥用量下不同钾肥用量及施用方法处理,测定稻麦周年的产量和组成因子,成熟期不同器官的氮、钾浓度和累积量,氮、钾利用效率及经济效益。试验结果表明,钾肥的施用显著提高了周年稻麦的产量,同时提高了稻麦的有效穗数、穗粒数和结实率,钾肥的利用效率和经济效益。稻麦周年钾肥(K₂O)的偏生产力(PFP)、农学效率(AE)、回收利用率(RE)和经济效益均以周年钾肥(K2O)土壤施用150 kg hm^-2 + 叶面喷施16.2 kg hm^-2 (K_S150 + K_F16.2)处理最高。氮肥用量的结果表明,相对于优化施氮量,高施氮量有利于提高水稻的氮素营养而增产,但对稻麦周年产量的影响不显著,且优化施氮量的氮肥利用效率及经济效益均高于高施氮量。因此,综合考虑土壤环境因素、经济效益和肥料资源管理,本地区最佳氮肥(N)用量为水稻200 kg hm^-2,小麦180 kg hm^-2;最佳钾肥(K₂O)用量及方法为水稻土壤施用90 kg hm^-2 + 叶面喷施9.7 kg hm^-2 (K_S90 + K_F9.7),小麦土壤施用60 kg hm^-2 + 叶面喷施6.5 kg hm^-2 (K_S60 + K_F6.5)。     

Selection for Increased Seed Nitrogen Accumulation in Common Bean: Implications for Improving Dinitrogen Fixation and Seed Yield

Estimates of N₂ fixation in segregating populations of bean plants based on ¹⁵N-isotope methods are technically demanding and expensive; therefore, indirect measures based on related traits including total seed N were used to select for improved N₂ fixation and yield. In 1985, six populations of F₂-derived F₃ families resulting from six parental lines crossed to a common tester were grown in field trials on a low-N soil. In 1986, 25 selected half-sib families and two populations of full-sib F₄ families were grown under similar conditions. Parents and a non-nodulating soybean line were included both years. Narrow sense (H_NS) heritability estimates based on parent-offspring regressions ranged from 0.57 for total seed N to 0.39 for shoot biomass in one population, but were near zero for all measured traits in a second population. Among the criteria used to identify parental lines with superior potential for producing progenies with high total seed N, testcross population means combined with estimates of realized heritability were the most reliable. Selection of the best F₃ families for total seed N resulted in F₄ families with increased total seed N and higher seed yields, while seed protein percentage was unchanged. When plants are grown on low-N soils, selection for total seed N offers a useful alternative to selection for increased N₂ fixation based on ¹⁵N-isotopic or total-N-difference method.     

Effect of plant density on selection for seed yield in two population types of Phaseolus vulgaris L.

Summary Pedigree selection for seed yield, using early generation yield tests, was practiced from the F₂ to F₇ in two populations of common bean (Phaseolus vulgaris L.) in three plant densities: 66, 133, and 266 thousand plants ha^-1 at CIAT-Palmira, Colombia. The six highest yielding lines selected from each plant-density, along with 13 parents, were evaluated in a 7×7 lattice design with three replications at the three densities utilized for selection, and at 399,000 plants ha^-1 in 1988 and 1989.Based on the mean performance of selected lines and the mean of the parents, selection for seed yield was effective in all densities in both populations. However, none of the lines selected from the population within the race Mesoamerica (TC 4673) significantly outyielded their best parent under any plant density. The highest yielding lines selected from the interracial population (TR 4635) outyielded their best parent irrespective of the plant-density used for selection. The highest yielding line originated from the highest density used for selection. Low density was neither good for selection nor for evaluation and identification of high-yielding cultivars of common bean. There was no significant difference between the mean yield of lines selected at the intermediate and high population densities. The effects of plant density, year, and their interactions were significant for seed yield.     

Old tall durum wheat cultivars are suited for dual-purpose utilization

The lateness, tallness and high vigour of old tall durum wheat cultivars could be advantageous for dual-purpose use and their high propensity for lodging should be reduced by grazing. A 3-year field trial was performed in Sardinia, Italy, in a typical Mediterranean environment. Crops of the durum wheat cultivar Senatore Cappelli were sown in October, and grazing was simulated by clipping half of the plots at the terminal spikelet stage of development. The forage biomass derived from clipping varied greatly between seasons (from 0.8 to 3.3 t ha⁻¹ dry matter) in response to the notable inter-seasonal variability in weather conditions. Cultivar Senatore Cappelli showed good recovery following clipping, with the ability to attain almost complete radiation interception well before anthesis. The high number of leaves that emerged after clipping might have contributed to this good recovery. Nevertheless, clipping reduced the dry matter produced by anthesis (16 t ha⁻¹ in clipped compared to 21 t ha⁻¹ in unclipped crops) as well as the final dry matter (DM_MAT) (19 t ha⁻¹ in clipped compared to 23 t ha⁻¹ in unclipped crops), although these differences disappeared when the clipped biomass was included. The lower lodging observed at anthesis in the clipped (21%) compared with unclipped crops (63%) likely reduced the difference between treatments. The lower DM_MAT of clipped treatments was reflected in a lower grain yield (GY) (3.4 t ha⁻¹ vs 4.2 t ha⁻¹ in the unclipped treatment). Clipping did not affect the amount of nitrogen present in the biomass, nitrogen uptake efficiency or radiation use efficiency. GY reduction after clipping was mediated by the reduction in spikes m⁻² and kernels m⁻² (KNO). Spike fertility was not affected by clipping, because the same amount of radiation was available for each spike (about 1 MJ). The period with reduced ground cover after clipping was reflected in an increased evaporation and reduced transpiration, which did not alter the total water used and increased the transpiration efficiency in terms of DM_MAT.Old tall durum wheat cultivars manifested good suitability for dual-purpose use in environments with low attainable yields because their low grain yield potential contributed to reducing the negative effects of clipping on GY. Their high straw yield and kernel protein percentage represented an advantage with respect to semi-dwarf cultivars.     

氮素实时管理对冬小麦产量和氮素利用的影响

为实现氮素效率和小麦产量的协同提高,以山东省泰安市和兖州市为试验地点,连续2年在4个田块上进行了基于土壤硝态氮测试的氮素实时管理试验。与农民习惯施肥相比,优化施氮处理提高产量0.87%～10.44%,平均5.82%;而氮肥用量减少38.61%～53.29%,平均46.70%;氮素吸收效率、氮素表观利用率和氮素农学效率分别增加36.67%～85.69%、58.49%～267.69%和34.16%～410.58%;氮肥偏生产力升高74.23%～124.87%;产/投比提高78.50%～112.09%。说明应用土壤硝态氮测试进行小麦氮肥实时实地管理达到了减少氮肥用量,提高氮素利用效率,增加产量和经济效益的目的。     

Reduction in kernel weight as a potential indirect selection criterion for wheat grain yield under terminal heat stress

Heat is an important abiotic stress during wheat (Triticum aestivum L.) grain‐filling in South Asia. A study was undertaken to determine effectiveness of selection for reduction in 1000‐kernel weight (TKWR) under heat stress to increase grain yield. Selection was made for low and high TKWR and selected progenies were evaluated in timely and late seeded trials at two locations in Nepal in 2003. One thousand kernel weight (TKW), biomass yield, grain yield, harvest index (HI), grain‐filling duration (GFD) and area under spot blotch progress curve per day (AUDPC/day) were examined. The low and high TKWR groups did not differ significantly for TKW, biomass yield, grain yield, HI, days to heading, GFD and AUDPC/day under timely seeding. However, low TKWR lines showed higher TKW, biomass yield, grain yield, HI, and GFD and lower AUDPC/day than the lines with high TKWR under late seeding. Realized heritability estimates for TKWR ranged from 0.68 to 0.85. The findings show that selection for low TKWR could be used as an indirect selection criterion to identify high grain yielding lines under terminal heat stress.     

旱稻297非结构性碳水化合物的生产与产量构成因子的关系

以旱稻297为试验材料,比较了在不施氮肥和150 kg hm-2的施氮量下旱稻297非结构性碳水化合物的生产能力、运转特点及其与产量构成因子的关系,分析了旱稻297氮肥投入与碳水化合物生产和产量形成间的关系。试验结果表明,开花前储藏的非结构性碳水化合物对产量的贡献率为32%~54%,施氮降低了开花前非结构性碳水化合物对产量的贡献率,相对而言开花后光合产物对产量的贡献率略有提高;开花前非结构性碳水化合物的转移效率为48%~65%,施氮后转移效率略有降低;总体而言,施氮降低了开花前后分配给单个籽粒的非结构性碳水化合物的数量,导致千粒重降低;在一定的范围内,随着开花期叶片中可溶性糖浓度的提高,结实率显著提高,但是随着穗中淀粉浓度的提高,结实率显著降低。因此,施氮后非结构性碳水化合物积累不足和转移效率降低同时限制了千粒重和结实率的提高,而叶片中可溶性糖浓度偏低和穗中淀粉浓度偏高限制了结实率的提高,是限制产量提高的主要原因。此外,旱稻297花后光合产物生产能力较低,是限制产量提高的又一原因。     

种植密度、氮肥和水分胁迫对玉米产量形成的影响

为阐明种植密度、氮肥和水分胁迫对不同玉米品种产量形成的影响,选用6个玉米品种,在两种密度(45 000株 hm^-2和75 000株 hm^-2)、两种施氮水平(纯氮112.5 kg hm^-2和337.5 kg hm^-2)和两种水分(前期干旱控水和正常灌水)处理下进行大田试验,调查玉米源库性状的主要生理参数和籽粒产量。结果表明,在环境压力较小时(低密度、高氮和正常灌水),玉米品种间籽粒产量、源性状(叶面积指数、穗位叶净光合速率和群体源供应能力)、库性状(群体库容量)、源库协调性状(群体库源比值、籽粒灌浆速率和收获指数)以及成熟期干物质积累量和吐丝期至成熟期干物质积累量差异较小,而逆境胁迫下(高密度、低氮和干旱),差异较大。环境压力较大时(高密度、低氮和干旱),叶面积指数、群体源供应能力、成熟期干物质积累量、吐丝期至成熟期干物质积累量、群体库容量和收获指数与籽粒产量呈显著或极显著正相关。由此说明,在玉米品种产量改良中要强化逆境人工选择,以适应自然选择,改善玉米品种逆境下的群体源库性状,增强吐丝期至成熟期叶片的光合生产效率,强源促库,提高逆境下的生产能力和适应性。     

Chickpea and faba bean nitrogen fixation in a Mediterranean rainfed Vertisol: Effect of the tillage system

Efficient management of legumes in order to maximize benefits depends on a correct field assessment of N₂ fixation. A field experiment was conducted during a 6-year period (2001–2002 to 2006–2007) in Córdoba (Southern Spain) on a rainfed Vertisol within the wheat-chickpea and wheat-faba bean rotation framework of a long-term experiment started in 1986. The aim was to determine the effect of tillage systems [no tillage (NT) and conventional tillage (CT)] on chickpea and faba bean N₂ fixation. Fixation was calculated using the ¹⁵N isotopic dilution (ID) and ¹⁵N natural abundance (NA) methods with the reference being the wheat crop. The strong inter-annual rain variation caused great differences in the behaviour of both leguminous plants with regard to grain yield, nodule biomass and N₂ fixation. The NT system showed more nodule biomass than the CT system in both legumes. The ID method was more accurate than the NA method in determining N₂ fixation. The average amount of fixed N in faba bean (80 kg ha^?1 year^?1) was much greater than that in chickpea (31 kg ha^?1 year^?1). The Vertisol under the NT system offered more favourable conditions for the stimulation of the N₂ fixation, with fixed N values that were significantly higher than under CT. The N added to the system through N₂ fixation was low in faba bean and virtually nonexistent in chickpea, only in terms of above-ground biomass.     

Selection response for carbon isotope discrimination in a Triticum polonicum×T. durum cross: Potential interest for improvement of water efficiency in durum wheat

This study has been conducted to evaluate the usefulness of carbon isotope discrimination (δ) in mature kernels as a criterion for the improvement of water-use efficiency and yield under drought in durum wheat. For this purpose, Triticum durum‘Om Rabi 5’ was crossed with T. polonicum pseudochrysospermum 9 (Tp9) which has been found to be more drought tolerant and to have a lower carbon isotope discrimination value of the grain. The F₂ population showed a wide segregation for carbon isotope discrimination. Further, divergent selections (selection of plants most different in carbon isotope discrimination) were made among individual F₂ plants, and for carbon isotope discrimination in F₃ progenies under field conditions. Selected F₃ and F₄ progenies were evaluated under field conditions for morphological and agronomical traits. Broad-sense heritability (h²_b), response to selection and realized heritability (h²_r) were high. The narrow-sense heritability (h²_n= 0.37 ± 0.047) indicated that additive and dominance effects were involved in the genetic control of carbon isotope discrimination. Negative correlations were noted between carbon isotope discrimination and grain yield and between carbon isotope discrimination and biomass yield within years and generations. An explanation of this result is attempted by analysing the relationships between carbon isotope discrimination and several phenological and morphological traits influencing the water-use efficiency. The divergent groups selected for low and high carbon isotope discrimination exhibited significant differences for days to heading, plant height, shape of the spike and number of spikelets per spike. Correlations were also found between carbon isotope discrimination and plant height, harvest index, shape of the spike, spike length, and number of spikes per plant. The potential use of carbon isotope discrimination as a criterion for the improvement of water-use efficiency in durum wheat is discussed by considering the genetics of this trait (variability, heritability, response to selection) and also the associations with phenological and morphological traits.     

施氮量和灌溉方式的交互作用对水稻产量和品质影响

本研究旨在探讨氮肥和灌溉方式对水稻产量和品质的的影响及其互作效应, 这对指导水稻高产、优质和高效栽培有重要意义。将两优培九(籼稻)和扬粳4038 (粳稻)种植于土培池, 设置常规灌溉(CI)、轻干湿交替灌溉(WMD)和重干湿交替灌溉(WSD) 3种灌溉方式及0氮(0N, 0 kg hm^-2)、中氮(MN, 240 kg hm^-2)和高氮(HN, 360 kg hm^-2) 3种氮素水平, 观察其对产量和稻米品质的影响。结果表明, 在中氮和高氮水平下, 产量、稻米的整精米率、外观品质和崩解值, 以轻干湿交替灌溉显著高于或优于常规灌溉。在中氮水平下, 重干湿交替灌溉的产量和稻米品质显著低于或劣于常规灌溉; 在高氮水平下, 重干湿交替灌溉的产量高于常规灌溉, 稻米品质在这两种灌溉方式间差异不显著。轻干湿交替灌溉显著提高了灌浆期剑叶光合速率、籽粒中ATP酶活性及根系中吲哚-3-乙酸、玉米素+玉米素核苷和脱落酸含量。说明灌溉方式和氮肥对产量和稻米品质具明显互作效应。在轻干湿交替灌溉和中氮水平下根系、叶片和籽粒生理活性增强是水稻产量提高和稻米品质改善的重要生理原因。     

西北绿洲灌区水氮耦合对燕麦品种陇燕3号耗水特性及产量的影响

灌水和施肥,尤其是施氮肥,是调控作物生长和增加产量的两大重要技术措施,其互作是燕麦高产高效栽培中重要因素。2014—2015年连续2个生长季,在甘肃河西绿洲灌区的田间试验设3个定额灌溉和3个施氮(纯氮)水平,研究水氮耦合对陇燕3号农田0~150 cm土层耗水量、棵间蒸发、产量及水分利用效率的影响。3个灌溉处理的灌水量分别为270 mm(I_1)、337.5 mm(I_2)和405 mm(I_3),3个施氮水平分别为90 kg hm~(–2)(N_1)、120 kg hm~(–2)(N_2)和150 kg hm~(–2)(N_3)。从播种到成熟,燕麦阶段耗水强度呈先增后减趋势,抽穗至灌浆是最大耗水期,且同一施氮水平下,阶段耗水强度随灌水量增大而显著增加。在全生育期内,棵间蒸发量(E)及土壤水分蒸发量占总蒸发量的比例(E/ET)表现先降后升趋势,且相同施氮量下,拔节至灌浆期随灌水量的增大而增大,而灌浆至成熟期则随灌水量的增大而减小。相同施氮量下,燕麦产量随灌水量增加而显著增加,水分利用效率却随灌水量增加而降低。产量N_3I_3最高(5466.0~5727.5 kg hm~(–2)),N_3I_2次之(5428.5~5678.5 kg hm~(–2)),N_1I_1最低(4504.5~4804.3 kg hm~(–2));水分利用效率N_3I_2最大(12.11~12.82 kg mm~(–1) hm~(–2)),N_3I_1次之(12.04~12.63 kg mm~(–1) hm~(–2)),N_1I_3最小(9.79~10.58 kg mm~(–1) hm~(–2))。由此表明,水氮耦合对燕麦水分利用及产量具有显著互作效应。施氮量150 kg hm~(–2)、灌溉定额337.5 mm是西北绿洲灌区燕麦种植较佳的节水、高产水氮管理模式。     

养分管理对直播稻产量和氮肥利用率的影响

为探明不同养分管理模式在实地农户种植条件下对直播水稻产量和氮肥利用率的影响。本试验于2011年6月至2013年11月在江苏省兴化市茅山镇基本农田保护区的田间稻麦轮作条件下,分别选取茅山东村、茅山西村和冯顾村各8个农户,开展3个不同养分管理模式试验,设置了不施肥对照(CK)、农民习惯施肥(FFP)和优化施肥(OPT1和OPT2)4个处理,主要研究了水稻产量及构成因子、氮累积分配和氮肥利用率等对不同养分管理模式的响应。结果表明：(1)施肥较不施肥显著提高水稻产量,优化施肥(226 kg N hm^-2)在较习惯施肥(333 kg N hm^-2)平均减氮32.1%的基础上显著提高水稻产量5.5%,增产原因是提高了穗粒数、结实率和千粒重;OPT2较OPT1平均增产3.1%,其原因是在孕穗期增施了钾肥(18 kg hm^-2 K₂O)。(2)优化施肥水稻植株各部位氮浓度、百千克籽粒需氮量和秸秆氮累积均显著低于习惯施肥,且降低营养器官的氮素分配比例。(3)优化施肥较习惯施肥显著提高水稻氮肥利用率,其氮肥偏生产力(PFP_N)、氮肥农学效率(AE_N)、氮肥回收效率(RE_N)和氮肥生理效率(PE_N)分别平均增加55.5%、79.1%、18.7%和48.7%。(4)水稻植株氮累积与产量呈显著正相关,且优化施肥单位氮累积的增产效果高于习惯施肥。因此,基于氮肥总量控制、分期调控和增施钾肥的养分优化管理措施可在实地农户直播稻种植上协同实现水稻高产和氮肥高效。     

钾肥用量对棉花生物量和产量的影响

近年来我国棉花生产,要么产量受制于缺钾引起的早衰,要么过量施钾导致生产成本增加和养分流失。然而,最适宜棉花生物质积累和增加产量的钾肥用量并不明了,因而也无适宜的施钾量推荐给农民。因此,采用大田试验(随机区组设计)和盆栽试验研究了钾肥用量对棉花(华杂棉H318)生物量和产量的影响。结果表明,K2处理(225 kg hm^–2)产量(1341 kg hm^–2)最高,单位面积成铃数(74个 m^–2)最多,盆栽试验结果具有相同趋势。同样,K2的棉株生物量,在各个取样时期都最大,尤其是生殖器官生物量。在5个钾肥用量(0~450 kg hm^–2)处理中,棉株生物质快速累积期几乎同时启动,但终止期存在一定差异。棉株生物质快速累积期间,K2处理无论是营养器官还是生殖器官生物质的平均累积速度、最大累积速度均最高。可见,在长江中游棉区中等肥力棉田,同时施用N 300 kg hm^–2和P₂O₅ 90 kg hm^–2的条件下,钾肥用量225 kg hm^–2更有利于棉花提高产量,因为在这一用量条件下棉株生物质累积速度最快、累积量最大。