Effect of varied N rates and N timings on yield, N uptake and fertilizer N use efficiency of a six-row and a two-row winter barley

The effects of N rates and N timings on yield formation, N uptake at five growth stages and fertilizer N use efficiency of six-row and two-row winter barley were evaluated in field trials conducted from 1990/91 to 1992/93 at the TU Munich's research station Roggenstein.

On average over 3 years the six-row cultivar yielded most at a total rate of 110 kg ha⁻¹ N including an early application of 40 kg ha⁻¹ N up to EC 30 (Zadoks scale). The two-row cultivar achieved maximum yield at a total rate of 140 kg ha⁻¹ N including early applications of 70 kg ha⁻¹ N up to EC 30. The highest yielding N-treatments of six-row barley regularly took up less nitrogen at EC 32 (95 kg ha⁻¹ N on average) than the non-optimally fertilized treatments, whereas full exploitation of the yield potential of two-row barley was associated with higher rates of N-uptake at EC 32 (113 kg ha⁻¹ N on average).

Lodging did not occur in the trials conducted in 1991 and 1992 and no difference was detected between the two cultivars in fertilizer N use efficiency. With six-row barley the N treatment giving maximum yield also led to an optimum fertilizer N use efficiency. Full exploitation of the two-row barley yield potential was associated with suboptimal fertilizer N use efficiencies.     

作物水分利用率的影响因素及其提高途径探讨

综述了作物水分利用率的研究进展。在探讨水分利用率内涵的基础上，阐述了作物水分利用率的影响因素如作物，环境因素，化学制剂，栽培措施和耕作制度等人类活动等影响因素，重点分析了土壤因素和化学制剂对作物水分利用率的影响，探讨了作物水分利用率的提高途径，包括优化种植结构；选用节水高产型品种；农田覆盖保水技术；水肥耦合技术；化学调控节水技术和节水灌溉技术等     

肥料深施对小麦生育性状、养分吸收及产量的影响

几年来在豫东潮土地区砂质土上进行的肥料深施效果试验研究结果表明,肥料深施对小麦的生育状况和经济性状有较大影响,肥料深施与浅施比较,可使小麦植株前期生长健壮,中后期生长稳健,落黄好,穗大粒多,籽粒饱满。可显著增加小麦养分吸收量,提高化肥利用率,肥料深施处理比浅施处理氮、磷、钾的吸收量,分别增加34.32￣67.81kg/hm2,3.22￣9.42kg/hm2和17.82￣39.84kg/hm2;氮素化肥利用率提高20.86￣41.1个百分点,磷肥利用率提高7.13￣15.39个百分点;肥料深施在小麦田里养分残留量较浅施的高,尽管一季小麦对土壤有机质耗竭不大,但对氮、磷素的残存已有差异。肥料深施对小麦产量、经济效益、化肥利用率有显著的影响,采用肥料深施技术比群众习惯施肥方法(浅施)可增产小麦337.1￣1183.5kg/hm2,增产率达7.6%￣26.6%,增加收益539.36￣1893.6元/hm2。     

关于上一轮县级土地利用总体规划中土地利用变化及生态环境效应的思考 ——以重庆市丰都县为例

基于重庆市丰都县1996年、2004年土地利用现状与2010年土地利用总体规划数据，运用特尔斐法、层次分析法、定量分析法，对丰都县1996—2004和1996—2010土地利用变化及生态环境效应进行对比定量分析研究。结果表明：（1）土地利用格局均发生了明显变化，耕地、未利用土地减少，园地、林地、水域、交通用地增加；（2）土地利用变化引起的生态环境质量变化均呈改善趋势，其主要原因是退耕还园、还林，以及未利用土地的开发利用；（3）规划与实施土地利用变化及生态环境效应差异太大；（4）土地利用总体规划与实际土地利用变化一致性很差，缺乏科学性和严肃性；（5）对规划土地利用变化引起的生态环境改善重视不够。最后提出新一轮土地利用总体规划修编的建议。     

种肥播施方式对红壤旱地油菜产量及肥料利用率的影响

In order to explicit proper sowing and fertilizing methods of rapeseed production in red-soil dryland, a two-year field experiment covering two rapeseed seasons (2017-2018 and 2018-2019) was conducted with four treatments of sowing and fertilizing methods to analyze the impact on yield formation and fertilizer use efficiency of rapeseed, including conventional sowing and fertilizing method (T1), sowing in row with surface broadcast fertilizing (T2), synchronous sowing in uniform row with side deep fertilizing (T3) and synchronous sowing in wide-narrow row with side deep fertilizing (T4). The results were as follows: The yield and fertilizer use efficiency of rapeseed in red-soil dryland were significantly affected by sowing and fertilizing methods. Besides, these differences were more significant in poor soil condition and drought season (2017-2018) than those in nutrient-rich soil condition and rainy season (2018-2019). Compared with T1 and T2, T3 and T4 promoted the yield formation and increased its fertilizer use efficiency significantly, whereas there was no significant difference between T3 and T4. Specifically, the technique of synchronous drilling sowing with side deep fertilizing could improve dry matter production during the whole growth period of rapeseed, especially from anthesis to maturity, with a corresponding rise of dry matter accumulation of both underground and aboveground after anthesis. Meanwhile, compared with the conventional cultivation, the technique of synchronous drilling sowing with side deep fertilizing increased the uptake of nutrients (N, P and K), effective plant density and maintained sufficient pod number, and thus improved the yield and fertilizer use efficiency of rapeseed. This study indicated that the technique of synchronous drilling sowing with side deep fertilizing had the potential of improving rapeseed productivity in red-soil dryland of southern China. Therefore, it should be suggested to promote the application according to local condition.     

等离子体处理玉米对化肥利用率的影响

2004年在吉林省桦甸市桦郊乡进行了等离子体种子4种不同剂量、6个处理区的试验。经过在拔节期、成熟期干物质的化验分析和测产，结果表明应用等离子体种子处理1.0A×2和1.5A×2的剂量能促进玉米吸收养分，（N＋P2O5＋K2O）总量比CK1提高10%以上；比CK1提高化肥利用率即提高氮肥、磷肥和钾肥利用率为7.4%~8.2%、 11.3%~19.7%和 15.7%~23.5%。明确了等离子体种子处理1.0A×2的剂量，比CK1增产8.2%，效果显著。     

三峡库区农业资源持续高效利用模式研究

针对三峡库区资源环境和农业生产现状及存在问题,探讨了农业资源持续高效利用的主要生产模式,即:种—养—加—销一体化模式、农林牧复合模式、农林复合模式、种—养立体农业模式和庭院高效生态农业模式等,并结合典型案例进行分析。此外,提出了实现农业资源持续高效利用的建议和对策。     

氮肥和栽插密度对杂交稻"两优培九"产量及氮素吸收利用的影响

以两系杂交稻两优培九为试材,研究不同N肥用量(纯N 0、112.5、225.0、337.5 kg/hm2)和栽插密度(22.5×104、27.0×104、31.5×104穴/hm2)对产量形成及N素吸收利用的影响。结果表明:(1)栽插密度对结实率和千粒重影响较小,对单位面积穗数和每穗粒数影响较大,在22.5×104~31.5×104穴/hm2的密度范围内,穗数与每穗粒数之间具有良好的互补性,因而产量差异未达显著水平。(2)N肥用量对每穗粒数影响较小,对穗数、结实率和千粒重影响较大,纯N用量为337.5 kg/hm2时,增穗作用不显著,反而极显著降低结实率和千粒重,导致减产。(3)稻株吸N量随供N水平的提高而增加,但植株含N率和N素累积量过高不利于叶鞘茎中的N素向穗部运转,降低籽粒N素积累量,导致结实率和千粒重显著下降而减产。(4)在中等肥力土壤上,施纯N 225.0 kg/hm2,栽插密度22.5×104穴/hm2,高峰苗控制在500.0万/hm2左右,有利于两优培九抽穗前茎鞘叶N素积累和抽穗后向穗部运转,能较好地协调穗数、结实率和千粒重的关系而获得高产。     

Parental influences on gas exchange rates in grain sorghum

Summary Significant genetic variation in CO₂ assimilation rate (A), stomatal conductance (g), and A: g ratio, which are indicators of intrinsic differences in productivity and water use efficiency (WUE), has been demonstrated in grain sorghum [Sorghum bicolor (L.) Moench] hybrids. The primary objective was to determine the possible parental influence on the components of the A: g relationship in sorghum hybrids across a range of water supplies. Thirty F₁ hybrids resulting from a 6 × 6 diallel crossing pattern constituted the genetic material. Field experiments were conducted using four water supply treatments established through differential irrigation. Carbon assimilation rate (A), g, and leaf water potential (_w) of individual leaves were monitored every 15 to 20 days. Genetic analyses revealed that general- and specific-combining ability effects were evident for A. However, reciprocal and maternal effects were more important in governing the A-g and A-_w relationships. Since the maternal effects were the major determinants in causing reciprocal differences, A can be improved by selecting specific female parents to exploit cytoplasmic factors or physiological characteristics of this parent. Substantial genetic variation in the A-g relationship resulting from significant genetic control of A offers the opportunity to impose selection for high A and stability of A, which might directly contribute to whole plant WUE and productivity in grain sorghum.Abbreviations A carbon assimilation rate - g stomatal conductance to water vapor - GCA General Combining Ability - SCA Specific Combining Ability - WUE Water Use Efficiency     

Nitrogen efficiency components of winter cereals

A model to describe the importance of different physiological processes to explain grain yield differences (ΔG_w) between cropping systems (Huggins and Pan, 1993) was modified to evaluate the nitrogen use efficiency of different cereals. The method uses measurements of grain yield (G_w), grain N (N_g), above-ground plant biomass (B), above-ground plant N (N_t), applied fertilizer N (N_f), and post-harvest inorganic soil N in control plots without fertilizer (N_h). The components are N supply (N_s), N uptake efficiency (N_t/N_s), assimilation efficiency (B/N_t), harvest index (G_w/B) and N harvest index (N_g/N_t). For a first verification of the model different winter cereal species, i.e., one genotype of winter wheat, one of winter rye and one of spelt wheat, were compared in a 2-year field experiments at two sites with different soil fertility and climate. The modified nitrogen efficiency component analysis provided a good understanding of yield differences at different levels of applied N and soil fertility. The method could be useful for selection of genotypes with a high N use efficiency in breeding programmes.