不同时期灌溉对华北平原春玉米穗粒数的影响

干旱胁迫是限制华北地区春玉米穗粒数形成的关键因子,探究不同时期灌溉对穗粒数的影响,对提高该地区春玉米产量和水分利用效率具有重要意义。在2014—2016年进行3年大田试验,设置拔节期、大口期、抽雄期、吐丝后15 d灌水和不灌水对照(CK),明确不同时期灌水对土壤水分变化、吐丝期穗位叶光合速率、穗粒数的影响及其相互关系。结果表明,在干旱和关键生育时期缺水的年份,灌水处理可以提高春玉米穗粒数,其中花期灌水较其他处理提高了1.4%~97.0%(2014年和2015年);而在多雨的2016年,各个灌水处理间穗粒数差异不显著。拔节期和大口期灌水促进了春玉米营养生长,提高了叶面积指数和生物量,但春玉米花期遭遇干旱胁迫仍会降低穗粒数。花期灌水处理在营养生长阶段受干旱胁迫影响,叶面积指数和生物量都降低,但保证了吐丝—授粉—籽粒建成关键阶段有充足的水分供应,其吐丝期光合速率较其他处理提高5.2%~32.8%。回归分析结果表明,吐丝期充足的土壤水含量可以显著提高春玉米光合速率(P=0.0034)和穗粒数(P=0.0137),但过多降水(降低光辐射)会影响光合作用及籽粒结实。因此,花期灌水是干旱年份保证春玉米穗粒数的重要措施。     

次生盐渍土暗管+竖井排水控盐技术模式筛选及效果评价

[目的]评价暗管、竖井工程在新疆南疆次生盐渍化土上的排盐效果,筛选出适宜的暗管布设间距.[方法]以新疆南疆垦区兵团第二师38团撂荒地次生盐渍化土为对象,于2016～2019年设置暗管+竖井田间排水控盐试验,选取3个相邻地块,暗管布设间距分别为6、8和10 m(依次记为T1、T2、T3),每个地块暗管埋深1.2 m,竖井...     

水肥一体化对小麦干物质和氮素积累转运及产量的影响

为探讨滴灌水肥一体化对小麦干物质和氮素积累、转运与产量的影响,于2016—2018年2个小麦生长季进行田间试验,设置3个氮(N)肥水平N1(180 kg/hm²)、N2(240 kg/hm²)、N3(270 kg/hm²)和3个水分(W)水平W1(生育期不灌水)、W2(生育期灌2次水)、W3(生育期灌3次水),9个处理分别为:W1N1、W1N2、W1N3、W2N1、W2N2、W2N3、W3N1、W3N2、W3N3。结果表明:连续2年,小麦植株干物质积累量在开花期和成熟期达到最大,与W1N1处理相比,W3N2处理下小麦开花期植株平均干物质积累量、成熟期植株平均干物质积累量、营养器官平均干物质转运量、平均干物质转运率和干物质转运对籽粒平均贡献率分别增加32.11%、13.34%、48.66%、56.34%、42.93%;连续2年,小麦植株氮素积累量在小麦开花期和成熟期达到最大,与W1N1处理相比,W3N2处理下小麦开花期和成熟期植株平均氮素积累量分别增加21.98%和20.30%;在小麦成熟期,与W1N1处理相比,W3N2处理下小麦茎+叶鞘平均氮素积累量、穗轴+颖壳平均氮素积累量、籽粒平均氮素积累量、营养器官平均氮素转运量、平均氮素转运率和营养器官氮素转运对籽粒平均贡献率分别增加20.19%、27.65%、35.99%、47.51%、20.91%和6.04%;连续2年,与W1N1处理相比,W3N2和W3N3处理下小麦平均产量分别增加31.88%和15.28%。研究表明,滴灌水肥一体化下W3N2处理是本试验的最优处理,能够促进营养器官干物质和氮素的积累与转运,有利于实现小麦高产高效。     

Note on relationship between leaf soluble carbohydrate and chlorophyll concentrations in maize during leaf senescence

Leaf senescence is typically associated with loss of chlorophyll and decline in photosynthetic capacity. The objectives of this study were: (i) to quantify the relationship between chlorophyll (SPAD) and soluble-carbohydrate concentrations in maize (Zea mays L.) leaves during leaf senescence and (ii) to examine whether this relationship differed between an old and a recent maize hybrid. Field experiments were conducted in 1995 at two locations. A range of leaf soluble-carbohydrate concentrations and SPAD values was obtained through various source-manipulation of source activity by defoliation and thinning. Defoliation treatments were imposed at 3, 4, and 5 weeks after silking. The thinning treatment was imposed at 3 weeks after silking. Two maize hybrids were composed: Pride 5 (old) and Pioneer 3902 (recent). Leaves at three leaf positions, near the topmost ear and the ear internode were sampled at weekly intervals, from 3 weeks after silking until visual completion of leaf senescence. Leaf and internode soluble-carbohydrate concentration declined following defoliation, although the response in leaves was delayed compared to that in the stem. SPAD readings and soluble-carbohydrate concentrations were positively correlated below a plateau value of 55 mg glucose equivalents g⁻¹ leaf. The correlation between SPAD and soluble-carbohydrate concentration was similar for the old and recent maize hybrid.     

Winter wheat canopy interception and its influence factors under sprinkler irrigation

Field studies on winter wheat canopy interception with its relations to leaf area index (LAI), plant height, drop diameter, wind speed, and water application intensity were carried out. Canopy interception was measured using the water wiping method. Results indicate that the maximum value of winter wheat canopy interception was not more than 1.0 mm, much smaller than presented by previous investigators. The total canopy interception for the growing season was 2.4 mm, only 1.3% of the total irrigation amount (194.6 mm), for four sprinkler irrigation events during 2003. Canopy interception increased as leaf area index and plant height increased. A linear regression model was developed to express the relationship of canopy interception with leaf area index and plant height. There was good agreement between the values of canopy interception measured using the water wiping method and estimated using the linear regression model. Results also indicate that canopy interception decreased as drop diameter and wind speed increased. An exponential relationship was found between canopy interception and drop size, and a linear relationship between canopy interception and the square of the wind speed. Water application intensity does not affect canopy interception significantly.     

耕作和保墒措施对冬小麦生育时期光合特征及水分利用的影响

为探明不同耕作保墒措施下冬小麦生育期间光合生理特征及其增产机理,采用田间试验,以常规耕作为对照,采用深松、秸秆覆盖、免耕、施用有机肥及保水剂等措施,研究了不同耕作和保墒措施对冬小麦生育期间光合作用、产量及水分利用效率的影响。结果表明:冬小麦光合速率和叶片水分利用效率均以孕穗期最高,而灌浆期最低。蒸腾速率和气孔导度均以扬花期最高。对不同处理而言,在各生育时期均以深松处理的光合速率和叶片水分利用效率最高,其次为秸秆覆盖处理。在拔节期、孕穗期和扬花期以有机肥处理的蒸腾速率最高,而灌浆期以秸秆覆盖的蒸腾速率较高,在全生育期对照的蒸腾速率均较低。气孔导度与蒸腾速率表现规律基本一致。不同耕作、保墒措施均提高了小麦的穗数、穗粒数及千粒重,以及小麦籽粒产量和水分生产效率,降低了小麦总耗水量;各处理中以深松处理的效果最佳,其产量和水分生产效率分别较对照提高19.6%和38.3%。相关分析表明:各时期的小麦光合速率及叶片水分利用效率均与小麦产量和水分生产效率呈正相关,且随生育期的推进,其相关性增强,特别在扬花期,光合速率对于小麦产量和水分生产效率的影响更显著。     

玉米抗茎倒伏能力相关性状与评价研究进展

茎倒伏造成玉米产量和品质下降,收获成本增加,籽粒生理成熟后无法继续田间站秆脱水,影响玉米机械化籽粒收获。关于玉米抗茎倒伏相关的性状,前人从植株形态、节间形态、解剖结构和化学成分等方面进行了大量研究,但结果不完全一致,同时这些性状对茎秆抗倒性作用大小的定量研究较少。本文综述了玉米抗茎倒伏能力的评价方法和指标、茎秆力学测定方法、抗茎倒伏能力相关性状的分析方法及其影响因素,提出了抗茎倒伏能力相关性状及评价研究中存在的问题和需要进一步关注的内容,希望为进一步研究玉米抗茎倒伏相关性状及其评价方法,培育抗倒伏品种和优化栽培措施提供参考。     

Application of Water-stress Models to estimate the Herbage Dry Matter Yield of a Permanent Grassland Pasture Sward Regrowth

This study proposed the concepts of water availability and the related growth support factor and defined them quantitatively. Based on these concepts, the water-stress-dependent effective temperature and global solar radiation accumulation were defined and used as regression variables in statistical modelling of herbage regrowth dry matter (DM) yield of a permanent grassland pasture sward under varying degrees of water shortage. It was found that the proposed method greatly improved the DM yield model accuracy when the influence of water stress on grass growth was prevalent. An effective model was obtained and is recommended for herbage yield prediction under such water-stress conditions. The recommended model predicted DM yield with a coefficient of determination of 0·92 and a mean square error of 0·21 t ha⁻¹. The model can be used for similar herbage regrowth of 3 weeks and beyond. Evaluation using an independent data set confirmed that the recommended model is robust and accurate. The methodology proposed can also be adapted to modelling the herbage growth of different sward types and different (re)growths under the influence of water stress.     

Variation of carbon partitioning in newly expanded maize leaves and plant adaptive growth under extended darkness

Plants must maintain a balance between their carbon(C) supply and utilization during the day–night cycle for continuous growth since C starvation often causes irreversible damage to crop production. It is not well known how C fixation and allocation in the leaves of crops such as maize adapt to sudden environmental changes. Here, to quantify primary C fixation and partitioning in photosynthetic maize leaves under extended darkness and to relate these factors to plant growth, maize seedlings were subjected to extended darkness(ED) for three successive days at the 6 th leaf fully expanded stage(V6). ED reduced plant growth and leaf chlorophyll levels but not the rate of net CO_2 exchange. As a result of the reduction in photoassimilates, the accumulation of starch and total soluble carbohydrates(TSC) in mature leaves also decreased under ED. However, the percentage of the daily C fixation reserved in mature leaves increased. These transient C pools were largely composed of TSC and were mainly used for consumption by increased nocturnal respiration rather than for transport. As the days went on, both the amount of C accumulated and the percentage of the daily fixed C that was reserved in leaves decreased, which could be largely accounted for by the attenuated starch synthesis in all treatments. The activities of ADPglucose pyrophosphorylase and soluble starch synthase decreased significantly over time. Therefore, this study concluded that both starch and TSC are involved in the coordination of the C supply and plant growth under a sudden C shortage but that they may be involved in different ways. While the ratio of reserved C to daily fixed C increased to maintain blade function under acute C starvation, both the amount and the proportion of C reserved in mature leaves decreased as plant growth continued in order to meet the growth demands of the plant.     

不同灌溉方式下氢、氧同位素分布与小麦水分利用特征

[目的]探明不同灌溉方式对小麦水分利用的贡献率及小麦根系吸水规律,可为合理应用灌溉用水提供科学依据。[方法]利用稳定氢氧同位素示踪法,研究了防雨棚条件下常规灌溉(X)与滴灌(D)不同灌水量条件下(X₁,D₁:15 mm; X₂,D₂:30 mm; X₃,D₃:45 mm)冬小麦生长期间土壤水稳定同位素变化特征,以及土壤耗水强度、光合生理特征及水分利用特征。[结果]随小麦生育期的推进,根系吸水逐渐加深。在拔节期小麦主要利用0—20 cm深度的土壤水; 在抽穗期X₂,D₁和D₂处理主要利用了0—20 cm土层的水分,但X₁处理主要利用了60—80 cm土层的水分,占53.9%,X₃处理主要利用了40—60 cm土层的水分,占77.0%。而D₃处理主要利用了0—60 cm土层的水分,占80.0%; 到灌浆期,X₁和X₂处理主要利用了0—60 cm土层的水分,分别占86.2%和90.6%,而X₃处理主要利用了40—60 cm土层的水分,占73.9%。而D₁和D₂处理不同土层的水分利用比例较均匀,分别介于7.1%～27.8%和13.0%～38.2%之间。D₃处理主要利用了20—40 cm土层的水分,占51.0%。除抽穗—灌浆期中水处理(D₂)及灌浆—收获期高水处理(D₃)外,滴灌均有效降低了小麦的日耗水量。与常规灌溉相比,滴灌D₂和D₃处理更利于提高小麦的光合速率和叶片水分利用效率。此外,滴灌处理在小麦抽穗期和收获期均有效提高了小麦的生物量。最终,滴灌较常规耕作小麦产量提高了21.6%～28.0%和水分利用效率提高了24.4%～36.7%,均以D₂处理最高。相关分析表明:小麦生长过程中,抽穗期0—20 cm土层水分贡献率和灌浆期80—100 cm土层的水分贡献率的提高对于其产量与水分利用效率的提高更为有利。[结论]滴灌更利于提供均匀的水分供给作物,同时减少水分无效蒸发,提高作物产量和水分利用率。