Effects of Boron Application on Yield,Foliar Boron Concentration,and Efficiency of Soil Boron Extracting Solutions in a Xanthic Ferralsol Cultivated with Banana in Central Amazon

Boron (B) is known to play important roles in the structures of cell walls and membranes and in the integrity and functions of membranes in plants. Under the conditions in the central Amazon region, there are few studies about this nutrient. In Brazilian soils, the hot-water B extraction method has been extensively used for evaluation of soil B status. However, difficulties with this method result in poor accuracy and precision of extraction of available B in soil. The objective of this study was to evaluate the yield, foliar concentration, and efficiency of B extracting solutions and the effect of B fertilization on B uptake in banana (Musa spp.) leaves and fruits, subgroup Cavendish (AAA), cultivated in a Xanthic Ferralsol (dystrophic Yellow Latosol) located in Amazonas State, Brazil. The experimental design was a completely randomized split plot, with four B rates (0, 4, 8, and 12 kg ha^?1), two harvest cycles (subtreatments), and four replicates. Available B was determined with seven extractant solutions: Mehlich 1, Mehlich 3, hot water, hydrochloric acid (HCl) 0.05 mol L^?1, HCl 0.1 mol L^?1, HCl 5.0 mol L^?1, and potassium chloride (KCl 1.0 mol L^?1). The application of B fertilizer increased the yield and B concentration in leaves and fruits. Hot water and KCl 1.0 mol L^?1 were the most efficient extracting solutions for the determination of available B in soil. The application of 3.4 kg B ha^?1 in the first cycle and 1.3 kg B ha^?1 in the second cycle guarantees an adequate nutritional status in banana plants.     

Yield,Yield Components,Soil Chemical Properties,Plant Physiology,and Phosphorus Use Efficiency in Soybean Genotypes

Expansion of soybean [Glycine max (L.) Merrill] cultivated in Brazil to regions with low fertility soils gave rise to studies on the possibility of obtaining highly productive cultivars with high nutrient use efficiency. An experiment in greenhouse conditions was conducted to assess phosphorus (P) use efficiency (PUE) by 13 soybean genotypes. The genotypes were grown in an Ustoxix Quartzipsamment with two P rates [0 (no P application) and 150 mg P kg^?1], whose source was monoammonium phosphate (MAP, P₂O₅ 44%). Shoot dry weight (SDW), grain yield (GY), grain harvest index (GHI), relative yield (RY), and physiological components (photosynthetic rate, stomatal conductance, respiratory rate, and internal CO₂ concentration) were influenced by soybean genotypes and P rates. Genotypes BMX Apolo RR, BRS 360RR, BRS 378RR, CD 219RR, DM 2302RR, TMG 7161RR, and Vtop RR were classified as non-efficient and non-responsive to P application, while BMX Potência RR, Vmax RR, FPS Solar RR, NA 5909RR, TMG 1066RR, and M 6210 IPRO were classified as efficient and responsive. Phosphorus application increased the values of physiological components, which was not observed for N, K, Ca, Mg, and S concentration in the leaves and grains. Soybean genotypes selection for increased P efficiency could help growers overcome the problem of soybean cultivation on new areas or degraded pastures.     

Variability on Yield,Nutritional Status,Soil Fertility,and Potassium-Use Efficiency by Soybean Cultivar in Acidic Soil

The use of cultivar with nutrient-use efficiency is an important strategy in the management of plant nutritional status, particularly potassium (K), because its high demand and the progressive impoverishment caused by the use of inadequate amounts cause frequent deficiency symptoms observed in soybean [Glycine max (L.) Merrill] crops. This study was conducted in greenhouse conditions in a completely randomized design with four replicates in an Typic Quartzipsamment soil aimed to assess the effect of applying two rates of K (50 and 200 mg kg^?1) on growth, shoot dry weight yield (SDWY) and seed yield (SY), nutritional status, yield components, and efficiency of K use in eleven cultivars of different characteristics and growth habits. The SDWY, SY, number of seeds per pod, number of pods, and estimated 100-seed weight showed significant interaction between cultivar and the K rates, with greater values at the rate 200 mg K kg^?1. Similarly, the concentration of nitrogen (N), phosphorus (P), K, calcium (Ca), magnesium (Mg), sulfur (S), boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) in leaves and grains varied according to the K rates and in the cultivar. The most K-use efficient cultivars were BMX Magna RR, BRS 232, BRS 284, BRS 294RR, NA 5909RR, and Vmax RR, whereas FTS Campo Mourão RR was inefficient. Regarding response to fertilization, the cultivars Vmax RR, BMX Magna RR, NA 5909RR, BRS 284, and BRS 294RR were found to be efficient and responsive, whereas the cultivar FTS Campo Mourão RR, BRS 232, BMX Potência RR, BRS 295RR, TMG 1066RR, and TMG 1067RR are inefficient and responsive to K application in the soil.     

不同土壤肥力水平下施氮对甘薯产量与氮肥利用率的影响

为探明不同土壤肥力条件下施用氮肥对甘薯产量和氮肥利用率的影响,选取鲜食型甘薯品种烟薯25号为试验材料,采用大田试验,研究了施氮对不同土壤肥力下甘薯产量及产量构成因素、干物质积累规律和氮肥利用率的影响。结果表明:不施氮条件下,甘薯蔓数、最大蔓长度、叶面积指数和产量均表现为高肥力中肥力低肥力(P0.05)。3种土壤肥力条件下,增施氮肥均能显著增加甘薯蔓数、最大蔓长度和叶面积指数(P0.05),但对最大蔓节间数影响不显著。高肥力、中肥力和低肥力地块分别在施氮量为50,100,150kg/hm~2时获得最高产量,分别较不施氮处理(N0)增产16.06%,29.63%和33.33%。与地力条件无关,增施氮肥均能提高甘薯地上部干物质累积量。中、低土壤肥力条件下,甘薯氮累积量随施氮量增加逐渐增加,而高土壤肥力条件下呈先增加后降低的趋势;高肥力地块氮肥利用率随施氮量增加而逐渐降低,中肥力地块先增加后逐渐降低,在100kg/hm~2时氮肥利用率最高,低肥力地块逐渐增加。综合产量和氮肥利用率,可知高肥力、中肥力和低肥力地块甘薯适宜施氮量分别为50,100,150kg/hm~2。     

Influence of Nitrogen on Growth,Yield, and Yield Components and Nitrogen Uptake and Use Efficiency in Dry Bean Genotypes

Dry bean is an important legume and nitrogen (N) deficiency is one of the most yield-limiting factors in most of the bean-growing regions. A greenhouse experiment was conducted with the objective to determine influence of N on growth, yield, and yield components and N uptake and use efficiency of 23 dry bean genotypes. Straw yield, grain yield, yield components, maximum root length, and root dry weight were significantly increased with the addition of N but varied with genotypes. The N × genotype interactions were also significant for most of these traits, indicating variation in responses of genotypes with the variation in N levels. There was significant difference in N uptake and use efficiency among genotypes. Most of growth and yield components were significantly and positively associated with grain yield. Based on grain yield efficiency index (GYEI), genotypes were classified into efficient, moderately efficient, or inefficient group in N-use efficiency. Nitrogen concentration was greater in grain compared to straw, indicating greater N requirement of dry bean genotypes.     

Phosphorus Use Efficiency of Common Bean Cultivars in Ethiopia

Phosphorus (P) deficiency in the soil is one of the major factors limiting common bean production in Ethiopia. A pot experiment was conducted in a glasshouse at Hawassa University in southern Ethiopia to evaluate twelve common bean cultivars for P use efficiency at three phosphorus rates (0, 120, and 240 kg P₂O₅ ha^?1). The results of the study revealed that the interaction effect of cultivar and P rates significantly (P < 0.01) influenced grain yield efficiency index (GYEI), grain yield and yield attributing traits, leaf P concentration, root length, diameter and surface area. Grain yield efficiency index at low and medium phosphorus rates indicated that Red-Wolaita, Dinkinesh, Tabour, Nasir and Haramaya are P-efficient, whereas Chore was found to be P-inefficient. These genotypic variations could be exploited for sustainable production of the crop by fitting suitable varieties to soils with variable P availability. Thus, the P-efficient cultivars indicated above could be recommended for cultivation by smallholder farmers in soil with low P availability that is dominant in the study area.     

Yield,Potassium Uptake,and Use Efficiency in Upland Rice Genotypes

Potassium (K) is an essential nutrient for higher plants. Information on K uptake and use efficiency of upland rice under Brazilian conditions is limited. A greenhouse experiment was conducted with the objective to evaluate influence of K on yield, K uptake, and use efficiency of six upland rice genotypes grown on Brazilian Oxisol. The K rate used was zero (natural soil level) and 200 mg K kg^–1 of soil. Shoot dry weight and grain yield were significantly influenced by K level and genotype treatments. However, K × genotype interactions were not significant, indicating similar responses of genotypes at two K levels for shoot dry weight and grain yield. Genotypes produced grain yield in the order of BRS Primavera > BRA 01596 > BRSMG Curinga > BRS 032033 > BRS Bonança > BRA 02582. Potassium concentration in shoot was about sixfold greater compared to grain, across two K levels and six genotypes. However, K utilization efficiency ratio (KUER) (mg shoot or grain yield / mg K uptake in shoot or root) was about 6.5 times greater in grain compared to shoot, across two K level and six genotypes. Potassium uptake in shoot and grain and KUER were significantly and positively associated with grain yield. Soil calcium (Ca), K, base saturation, acidity saturation, Ca saturation, K saturation, Ca/K ratio, and magnesium (Mg)/K ratio were significantly influenced by K application rate.     

Evaluation of Nitrogen Fertilization Patterns Using DSSAT for Enhancing Grain Yield and Nitrogen Use Efficiency in Rice

Temporal variation of rice growth and nitrogen (N) uptake generally follow a sigmoid curve and may respond positively to the N-fertilizer application at critical growth stages. In this study, it was hypothesized that the amount of N-fertilizer applied at critical growth stages possibly follows a geometric pattern such as line, parabola, and sinusoidal to attain maximum yield and nitrogen use efficiency. To test and identify the best pattern, short-term modeling-field testing-long-term modeling strategy was followed. The patterns with the highest simulated yield and nitrogen use efficiency from short-term modeling were tested in the field. Finally, long-term evaluation of N-fertilization patterns was performed using 25 years of historical weather data, resulting in the line pattern with 14% more yield and 25% less NO₃^? leaching in comparison to the conventional N-Fertilization pattern. Therefore, line pattern may be adopted to enhance the yield and nitrogen use efficiency in rice.     

土壤肥力质量与施氮量对小麦氮肥利用效率的综合定量关系研究

耕地土壤肥力及施氮量对于小麦产量和氮肥利用率均具有重要影响,但它们综合影响的定量关系及相对贡献率并不清楚。在太湖流域常熟市研究区,通过设置不同土壤肥力与施氮量的小麦田间试验,研究施氮量、土壤肥力综合质量指数对小麦产量和氮肥利用率的影响,并利用多元回归方法拟合他们之间的定量关系方程,分析揭示施氮量与土壤肥力综合质量指数对小麦产量和氮肥利用率综合影响的相对贡献率。结果表明,提升施氮量和土壤肥力综合质量指数,有利于增加小麦产量,但不利于小麦氮肥利用率提升;土壤肥力综合质量指数对小麦产量和氮肥利用率的影响大于施氮量,两者对产量和氮肥利用率的相对贡献率比值分别为1.09∶1和1.32∶1。表明通过提升土壤综合肥力、削减氮肥施用量,达到粮食与生态双重安全目标,培育和提升耕地土壤质量显得更为基本和重要。     

植物诱抗剂对尿素氮利用率和小麦产量的影响

为研究植物诱抗剂配伍尿素和控释尿素对小麦产量及构成因素、氮肥利用率和土壤养分的影响,通过对尿素包膜(CRU)、包膜尿素配施诱抗剂(CRUR)、尿素配施植物诱抗剂(UR)的处理方式,进行了小麦大田试验,以尿素(U)和无氮(CK)处理为对照,共设置5个处理。结果表明:(1)尿素配施诱抗剂处理的小麦产量和氮肥利用率比尿素处理显著提高23.6%和10.1个百分点,纯收益显著增加3 269元/hm2。(2)CRUR处理较CRU处理小麦产量和氮肥利用率显著增加14.5%和12.4个百分点,纯收益显著提高2 361元/hm2;比UR处理显著提高16.3%和11.9个百分点,纯收益增加2 446元/hm2。(3)在小麦拔节期即氮肥最大效率期,CRUR处理的土壤硝态氮含量比CRU处理显著增加29.5%,比UR处理显著增加88.2%;CRUR处理的土壤铵态氮含量比UR处理显著提高34.4%。控释尿素配施植物诱抗剂可实现两者协同增效,显著提高小麦生育关键期土壤氮素供应强度、产量、氮肥利用率和纯收益,为促生型缓控释肥料的研发与应用提供依据。     

晋南旱垣土壤质地和茬口对小麦产量及水分利用效率的影响

在山西临汾、襄汾采用大区对比法研究了土壤质地和茬口对小麦产量及水分利用效率的影响。结果表明:小麦产量轻壤土质夏季复播作物茬口低于夏季休闲茬口,而中壤土质夏季复播作物茬口高于夏季休闲茬口;小麦播前贮水量轻壤土质夏季复播作物茬口低于夏季休闲茬口,而中壤土质夏季复播作物茬口高于夏季休闲茬口;轻壤土质全生育期0~100 cm,0~200 cm,100~200 cm的耗水量均以休闲茬口>大豆茬口>绿豆茬口,中壤土质拔节期贮水量、拔节至成熟阶段0~100 cm,0~200 cm,100~200 cm的耗水量均以花生茬口>谷子茬口>休闲茬口;水分利用效率中壤土质明显高于轻壤土质,各茬口间的极差中壤土质大于轻壤土质。该项研究为以旱地小麦为主要作物的轮作制度选择土壤质地和夏季复播(春播)作物茬口提供了理论依据。     

膜下滴灌制度与生物炭用量对玉米生长及水氮利用效率的影响

为探明干旱地区盐碱地膜下滴灌不同灌水下限施用生物炭对玉米产量和水肥利用效率的响应差异及相互影响关系,提出较优的灌溉制度和生物炭用量。连续2年在河套灌区盐渍化农田玉米生长阶段进行小区控制试验,设计3个灌水下限[土壤基质势为-15(W15),-25(W25),-35(W35)kPa,灌水定额为22.5 mm]和3个生物炭用量水平[0(B0),15(B15),30(B30)t/hm²],2因素完全随机试验设计,共9个处理。测定并分析玉米全生育期0—15 cm土壤理化性状、作物生长特征和水氮利用效率。结果表明：不同灌水下限施用生物炭整体提高玉米全生育期土壤含水率、有机质和碱解氮含量,同一灌溉水平下生物炭用量越高,各指标提升的幅度越大。施用生物炭提高玉米地上部干物质积累量和产量,灌溉水利用效率和氮肥偏生产力显著提高,且生物炭施用当年的效果普遍优于翌年。相较于不施用生物炭的对照,W15、W25、W35条件下,B15使玉米产量平均增加12.8%,10.3%,14.2%,灌溉水利用效率提高14.2%,10.4%,12.9%,氮肥偏生产力提升12.8%,10.4%,14.0%,其节...     

晋南旱垣土壤质地和茬口对小麦产量及水分利用效率的影响

在山西临汾、襄汾采用大区对比法研究了土壤质地和茬口对小麦产量及水分利用效率的影响。结果表明：小麦产量轻壤土质夏季复播作物茬口低于夏季休闲茬口,而中壤土质夏季复播作物茬口高于夏季休闲茬口;小麦播前贮水量轻壤土质夏季复播作物茬口低于夏季休闲茬口,而中壤土质夏季复播作物茬口高于夏季休闲茬口;轻壤土质全生育期0～100 cm,0～200 cm,100～200 cm的耗水量均以休闲茬口〉大豆茬口〉绿豆茬口,中壤土质拔节期贮水量、拔节至成熟阶段0～100 cm,0～200 cm,100～200 cm的耗水量均以花生茬口〉谷子茬口〉休闲茬口;水分利用效率中壤土质明显高于轻壤土质,各茬口间的极差中壤土质大于轻壤土质。该项研究为以旱地小麦为主要作物的轮作制度选择土壤质地和夏季复播（春播）作物茬口提供了理论依据。     

覆盖方式对玉米农田土壤水分、作物产量及水分利用效率的影响

为了加深对地面覆盖措施保墒增产机理的认识,通过大田试验,对黄土高原南部旱塬区秸秆和地膜两种覆盖方式下玉米农田土壤水分动态、作物产量形成和水分利用效率进行了分析。结果表明:在试验年份,与不覆盖相比,秸秆覆盖后玉米生育期内土壤储水量提高了5.2%～8.4%(P<0.05),籽粒产量和水分利用效率分别降低了7.8%和3.5%;而地膜覆盖下土壤储水量的差异不显著,但显著提高了产量构成指标,其籽粒产量和水分利用效率分别较对照提高了14.1%和10.6%(P<0.05),显示后者抑制土表蒸发所增加的土壤水分更多地、更有效地被作物根系吸收利用了。从产量形成和水分利用效率角度分析,本地区旱作玉米农田使用地膜覆盖有较好的保墒增产效果。     

有机肥施用量和耕作方式对旱地土壤水分利用效率及作物生产力的影响

为了探索旱地农业连作春玉米田不同保护性耕作措施下土壤蓄水保墒效果与不同施肥处理组合下春玉米的增产增收效应,在2014—2016年通过大田试验,研究了旱地农田冬闲期免耕、深松和翻耕3种耕作方式对玉米田冬闲期蓄水保墒效果及玉米生育期3种耕作处理与高、中、低有机肥3种施肥处理组合对春玉米生育期土壤水分动态、产量和经济效益的影响。结果表明,免耕和深松与翻耕相比,蓄水效果较好;2个试验年度冬闲期,免耕和深松较翻耕分别高1.3,0.9个百分点。免耕、深松较翻耕处理0—200 cm土层2年土壤平均贮水量分别增加20.8,22.1 mm;玉米生长生育期在高有机肥条件下,免耕、深松较翻耕处理0—200 cm土层土壤平均贮水量分别高44.2,34.6 mm;以高有机肥深松处理产量、WUE和纯收益最高。2年平均产量、WUE和纯收益分别为9 332.40 kg/hm^2,22.01 kg/(hm^2·mm)和5 104.1元/hm^2,高有机肥免耕处理次之,较高有机肥免耕处理增产和增收分别为7.4%和3.9%。综合考虑各处理土壤蓄水保墒效果和玉米增产增收效应,高有机肥深松是旱区连作玉米田最优的耕作和施肥处理组合。     

紫色土地区水钾耦合对油菜产量及水分利用效率的影响研究

为探讨川中丘陵紫色土地区不同决策目标下油菜适宜的水钾用量,通过水钾耦合模型的建立与分析,研究了不同钾素水平和水分处理对油菜产量及水分利用效率的影响。结果表明:在本试验条件下开花期土壤水分对产量影响最大,蕾苔期次之;油菜总产量增长速率随水钾用量的增加呈现先增后减趋势;水钾耦合对产量和水分利用效率均有促进的正效应,效应大小顺序为:水钾耦合 > 土壤含水量 > 施钾量。籽粒产量最高值出现在蕾苔期开花期高钾高水处理,此时水分利用效率（WUE）为14.6 kg/（hm²·mm）,而水分利用效率最高值出现在蕾苔、开花期。高钾和土壤水分分别控制在0.66 g/kg,θ_f58.7%组合,但是籽粒产量降低约19.7%。在季节性干旱和酸性紫色土区油菜推荐的水钾模式为:蕾苔、开花期土壤水分分别控制在θ_f68%,θ_f80%,施钾量控制在0.57 g/kg,此时籽粒产量和水分利用效率均较高且经济效益达到最大。     

优化氮肥用量和基追比例提高红壤性水稻土肥力和双季稻氮素的农学效应

【目的】 优化氮肥用量和基追比例是实现氮肥减施和提高肥料利用率的重要途径。本研究在南方典型双季稻种植区进行定位试验,通过对土壤肥力与氮素农学效益进行综合评价,以期提出适合当地土壤和水稻种植条件的氮肥减施模式。 【方法】 以南方典型红壤区双季稻种植体系为研究对象,于 2014～2015 连续进行了 4 季大田定位试验,设处理:1) 不施氮肥 (T1);2) 当地农民习惯施氮 (T2),早稻、晚稻各施 N 165 和 195 kg/hm2,基肥∶蘖肥∶穗肥比分别为 60∶40∶0、40∶30∶30;3) 在 T2 处理基础上减施氮肥 20% (T3),即早稻施 N 135 kg/hm2,晚稻施 N 165 kg/hm2,基肥∶蘖肥∶穗肥比均为 40∶30∶30,并以 20% 有机氮代替普通化肥氮。分析了成熟期水稻产量和植物样氮素含量,测定了 0—20 cm土壤微生物量碳、氮含量,土壤 pH、有机质、全氮、速效钾和有效磷等理化指标,计算了累计氮肥利用率和氮肥农学效率,分别利用内梅罗指数法和灰色关联度法综合评价了土壤肥力效应以及各施肥模式的综合效益。 【结果】 1) 各处理土壤综合肥力指数 (IFI) 值由高到低为 T3 > T2 > T1;与 T2 处理相比,优化氮肥用量和基追比例的 T3 处理 IFI 值提高 2.34%,土壤微生物量碳含量提高了 4.37%～25.39%,土壤微生物量氮含量提高了 17.85%～29.24% (P < 0.05)。2) 与 T2 处理相比,2014–2015 年 T3 处理累计氮肥农学效率显著提高了 29.66% (P < 0.05),累计氮肥表观利用率显著提高了 28.82% (P < 0.05);2014 年各处理水稻总产量无显著差异,2015 年水稻总产量 T3 处理比 T2 处理提高了 5.26%,两年水稻总产量,T3 处理提高了 2.38%。3) 对土壤养分指标、土壤微生物指标和氮素农学效率指标进行关联度分析,2014～2015 年 T3 处理关联度最大,分别为 0.9999 和 1.0000,在土壤肥力和氮肥农学效应综合评价中最优,表明优化氮肥用量和基追比例能够实现氮肥减施以及肥料利用率的提高。 【结论】 在当地农民习惯施氮的基础上减施 20% 化肥氮,以有机氮替代,并适当提高化肥氮在抽穗期的比例,能够保证土壤综合肥力的可持续性、氮素养分持续高效利用和水稻持续稳产。      

杉木林改造前后的土壤肥力对比分析及综合评价

基于福寿林场3个龄组杉木(Cunninghamia lanceolata)生态公益林9块固定样地的实测数据,选用土壤有机质、全氮、全磷、碱解氮、有效磷、速效钾、土壤容重和pH值8个指标对杉木林改造前后的土壤肥力进行了对比分析,并基于乘除法原理提出了土壤肥力综合评价指数和评价等级。结果表明:与改造前相比,改造后3个龄组杉木生态公益林0~20 cm表层土壤的有机质、全氮、全磷、碱解氮、有效磷、速效钾的含量都有不同程度的提高,且杉木幼、中林提高程度更明显,改造后的杉木幼、中龄林的土壤容重略有下降,pH值略有增加,但杉木近熟林的土壤容重和pH值基本保持没变。说明补植了阔叶树种栾树(Koelreuteria bipinnata)和马褂木(Liriodendron tulipifera)的杉木幼龄林和补植了阔叶树种栾树、马褂木和深山含笑(Michelia maudiae)的杉木中龄林土壤质量的改善程度明显优于在林下补植了红豆杉(Taxus chinensis)的杉木近熟林,通过树种结构调整改造后的3个龄组杉木林土壤肥力综合评价指数值也有不同程度的提高,土壤肥力质量从差变为较差。相比传统的土壤肥力综合评价指标,本文提出的土壤肥力综合评价指数不需要计算指标权重,计算量小,而且可以根据不同的土壤系统,对模型参数的个数适当增减,适用性较强。     

平托花生在红壤果园的水土保持作用与综合利用研究

果园套种平托花生具有良好的水土保持作用,连续4年定位测定表明,套种平托花生的果园发生地表径流38次,径流总量61t/hm2,无泥沙流失;而对照处理发生地表径流178次,径流总量2482 4t/hm2,流失泥沙42 26t/hm2。平托花生还有改善土壤理化性状的作用,果园套种平托花生3年后,0～20cm的土壤容重为0 98g/cm3,土壤空隙度25 73%,土壤含水量22 5%;而对照分别为1 06g/cm3,18 6%,21 5%。套种平托花生3年后土壤pH值从5 12提高到6 25,酸性改善;有机质从15 26g/kg提高为19 30g/kg;全氮从0 79g/kg提高到1 04g/kg;全磷从0 25g/kg提高为0 30g/kg;但全钾从23 23g/kg下降到19 64g/kg。平托花生营养丰富、适口性好。以平托花生喂养肉兔,平均日增重为21 67g,高于饲喂野生杂草(10 73g)。平托花生以扦插繁殖为主,采用10cm×10cm的扦插距离,在山地(有机质5g/kg)30天后覆盖度达到49%,45天达到87%,60天达到91%;而园地(有机质15g/kg)30天就可以达到80%。采用20cm×20cm的扦插距离,山地需75天达到80%的覆盖,园地75天达到89%。     

Internal and External Phosphorus Requirements for Optimum Grain Yield are Associated with P-utilization Efficiency of Wheat Cultivars

ABSTRACT

Considerable variation exists among wheat cultivars for phosphorus (P) acquisition and utilization to produce higher yields. We investigated critical P requirements for optimum grain yield of two wheat cultivars contrasting in P-use efficiency, i.e., NIA-Sunder (P-efficient) and NIA-Saarang (P-inefficient). Grain yield, P accumulation, and other P-efficiency relations of both cultivars increased with progressive addition of P, but at variable rates. NIA-Sunder exhibited higher grain yield, grain P concentration, harvest index, and P-use efficiency at all P levels as compared to NIA-Saarang. Internal P requirement for achieving 95% relative grain yield in NIA-Sunder and NIA-Saarang was obtained when P concentration in their grains was 4.07 and 3.48 mg g^?1 recorded at external P levels of 57.2 and 78.1 mg kg^?1 soil, respectively. Overall, NIA-Sunder accumulated 15% more grain P and required 27% less external P for attaining 95% relative yield than P-inefficient cultivar. Results suggested that internal and external P requirements aiming at optimum grain yield are associated with genotypic variations in wheat cultivars for P-utilization efficiency.