种植密度与行距对秋闲田饲用甜高粱草产量的影响

为了秋闲田饲用甜高粱丰产丰收,探索其高产栽培技术。采用列区试验设计与软件IBM.SPSS.Statistics.v22 的LSD法,对秋闲田饲用甜高粱的种植密度与播种行距进行了单株生产力及其草产量的比较试验。结果表明：种植密度与行距对秋闲田饲用甜高粱单株生产力、草产量均具有重要影响。明确了秋闲田饲用甜高粱高产配套栽培技术的优化组合：单株生产力最大的优化组合为A1B4,即种植密度为7.50 万株/hm2 与播种行距为40 cm 的配置;获得最高产量的优化组合为A2B4,即种植密度为22.50 万株/hm2与播种行距为40 cm的配置。研究结果为秋闲田种植饲用甜高粱的生产实践提了供理论依据和技术支撑。     

农田防护林主要间距离的确定——基于林带结构与风速降低的关系

Relative windspeed reduction was measured behind nine relatively narrow, homogenous tree windbreaks with porosities between 0.13–0.33, and behind 28 combinations of model stubble barriers representing 25 different optical porosities (0.00–0.80). The optimum porosities observed were 0.25 and 0.13 for tree windbreaks and stubble barriers respectively. Based on the relationship between windbreak structure (optical porosity) and wind reduction, the chief indices for determining spacing interval, i.e., the windbreak structure index (δ) and the parameter of microclimate, represented by the problem wind (L _rp ), were determined. Additionally, investigations on shelterbelt trees were carried out, and stem-analysis techniques were used, to develop a method for determining the mature height of tree windbreaks (H ₀). Optimal spacing intervals between windbreaks could be predicted from the indices of a given windbreak structure, percentage of reduction of windspeed desired and tree growth model. A hypothetical example for determining the spacing interval of principal poplar windbreaks is given at the end of this paper. The results can be applied not only to tree windbreak design but also to other plant materials and artificial barriers for wind protection. Foundation item: This study was supported by Innovation Research Project of Chinese Academy of Sciences Biography: ZHU Jiao-jun (1965-), male, Ph. Doctor, PhD advisor. Professor of Institute of Applied Ecology, the Chinese Academy of Sciences, China, Scholar researcher of Faculty of Agriculture, Niigata University, Japan. Responsible editor: Song Funan     

Subsurface Drainage for Rehabilitation of Waterlogged Saline Lands: Example of a Soil in Semiarid Climate

In irrigated agriculture of arid and semiarid regions, soil salinity, coupled with waterlogging, is a serious problem. Provision of subsurface drainage seems to be a prerequisite for optimal crop production. A study was conducted to evaluate the long term (8-year) impact of a subsurface drainage system on soil properties and yields of wheat. The study was located in a severely affected, waterlogged, barren, sandy loamsaline soil (Comborthids). The subsurface drainage system was installed at a 1.75 m depth with three drain spacings (25, 50, and 75 m). The drains facilitated reclamation of the waterlogged saline land which had variations in salt removal with space and time. The removal of salts from the root zone varied initially with distance from the drain and with depth. However, after a few years, the variations were reduced and the land was reclaimed sufficiently to grow most of the crops of the region. Plots provided with a drain spacing of 75 m required more time for complete reclamation compared to plots provided with 25 m drain spacing. Leaching through subsurface drainage increased soil porosity, modulus of rupture, infiltration rate, organic carbon, available nitrogen, phosphorus, potassium, and available water, and decreased bulk density differently in the three drain spacings (20, 50, and 75 m). In the 75 m drain spacing plots, soil salinity (EC e ) and water content remained higher than in the 25 and 50 m drain spacing plots. Soil EC e and water content were less near the drains, were highest in areas midway between the drains, and the effects were more apparent in the summer season. Wheat grain yield decreased with increasing drain spacings in the initial years of reclamation. With the gradual improvement in soil salinity, yields from plots with a 75 m spacing reached those of the narrower drain spacing plots by the fourth year. It was concluded that by installing a subsurface drainage system in a monsoon climate, waterlogged saline soils can be reclaimed by the natural leaching that can take place from rainfall. The optimum yield can be attained with a drain spacing of 75 m, which is 50% more than the design spacing of 50 m. Faster reclamation and more yield were obtained with a 25 m drain spacing and was achieved at a higher cost for the more expensive drainage system.     

行距配置与密度对奶花芸豆群体冠层结构及产量的影响

研究了在高产条件下，不同行距配置、密度对奶花芸豆群体田间小气候变化、冠层结构、光能分布与利用特性及产量构成的影响。结果表明在适宜的群体密度下，通过扩大行距，减小株距，有利于优化群体结构，显著影响小气候因子在群体中的分布，改善个体生育状况和群体通风透光条件，使产量构成因素实现最佳配置，充分利用地力和空间，从而获得最佳产量。在实验条件下，密度15000株/hm2，行距60cm或采用80+40cm宽窄行、株距10~15cm是奶花芸豆理论上的田间最佳分布的配置。     

不同行距配置对平安8号生理特性及产量的影响

[目的]研究不同行距配置对平安8号生理特性及产量的影响。[方法]以平安8号为试验品种,设置3种不同行距处理,研究不同行距配置对平安8号生理特性和产量的影响。[结果]平安8号在10 cm×30 cm行距模式下群体总茎数、叶面积指数、干物质积累、灌浆速度等均高于其他2种行距模式。[结论]实际生产中,针对株型松散的品种应采用宽窄行种植模式以提高产量。     

行距配置和密度对蒜茬花生生育性状及产量的影响

[目的]探明花生-大蒜轮作条件下花生的最佳种植密度和行距配置。[方法]采用二因素裂区试验设计,以山花9号为试验材料展开田间试验,研究不同行距配置和密度对蒜茬花生生育性状、干物质积累及产量的影响。[结果]行距和密度的互作效应不显著。不同行距配置下,35 cm行距处理的荚果干物质积累和产量均高于其他处理;不同种植密度下,24万穴/hm2密度处理的产量最高。[结论]鲁西地区花生-大蒜一年两作种植模式下,采用地膜覆盖,单粒播种,种植密度为24万穴/hm2、行距为35 cm时花生产量最高。     

安徽省玉米种植密度现状及调控对策

为了揭示安徽省玉米种植密度现状,提出适合安徽不同种植习惯的密度调控对策,为安徽省玉米单产的提高提供科学依据。笔者连续2 年对安徽省玉米产区7 市24 县区进行密度取样调查,分析其株距、行距等密度构成因子。结果表明：安徽省玉米种植平均行距0.55 m,平均株距0.32 m,平均种植密度66870 株/hm2,总体合理,但区域分布不均,主要分为6 个种植习惯区,针对这6 个种植习惯区提出了适度增密,推广耐密品种,调整种植行距,推广玉米播种机械等4条对策。     

行距配置和化控对冬小麦茎秆质量和抗倒性能的影响

为明确行距配置和多效唑化控对小麦茎秆质量和抗倒性能的影响规律,采用裂区试验,研究了行距配置(12 cm等行距、15 cm等行距、12.5 cm+12.5 cm+20 cm共3个水平)和多效唑化控(对照、起身期化控、拔节期化控3个水平)对冬小麦茎秆形态的影响.结果表明,株高、茎秆重心高度和节间长度基本上以15 cm等行距处理的最小,12 cm等行距处理的最大,这2种行距配置之间拔节期和开花以后的株高及成熟时基部节间长度差异均显著(P＜0.05);而基部节间粗度、秆壁厚度、单位长度节间干重、茎秆机械强度及抗倒伏指数基本上以15 cm等行距处理的最大或较大,12 cm等行距处理的最小.起身期和拔节期喷施多效唑处理的小麦株高、节间长度和茎秆重心高度显著降低,基部节间粗度、秆壁厚度、茎秆机械强度有所增加,抗倒伏指数显著增大.除基部第二节间长度外,行距配置与化控互作对其他指标的影响不显著(P＞0.05).抗倒伏指数与株高、节间长度、重心高度呈极显著(P＜0.01)负相关(相关系数分别为-0.42、-0.76和-0.63),与茎秆机械强度、第1和第2节间单位长度干重、第2节间秆壁厚度呈显著或极显著正相关(相关系数分别为0.97、0.42、0.64和0.64),与第2、第3节间粗度和第3节间秆壁厚度相关不显著.因此,15 cm等行距种植配合起身期或拔节期多效唑化控,可提高小麦茎秆质量和抗倒性能.     

Effect of wide spacing on tree growth, branch and sapwood properties of young Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] in south-western Germany

The influence of stand density on Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] is conceptually understood, but for wide spacings not well quantified, particularly in Europe. This study used 41 trees from 7 different locations in south-western Germany to compare important tree- and branch-level attributes across three different densities, namely 100, 200, and 1,200 stems ha⁻¹. In general, there were only a few tree and branch attributes that were significantly different between the 100 and 200 ha⁻¹ densities. Crown projection area and diameter of the thickest branches were the most important differences between the 100 and 200 ha⁻¹ densities. The most obvious and significant differences in this study were between 100 and 1,200 ha⁻¹ densities, where nearly every examined tree and branch attributes were statistically significant. However, relative sapwood area, the number of branches, branch angle, and the occurrence of spike knots were insensitive to stand density. Although the two lowest stand densities in this study represent rather extremely wide spacings, these results still have important implications for the development of effective thinning regimes for Douglas-fir in south-western Germany. Important management recommendations from this study include thinned stands should be maintained to at least 200 stems ha⁻¹ to maintain high log quality and stand stability. Furthermore, even at stand densities exceeding more than 1,200 trees ha⁻¹ planted trees, artificial pruning may even be necessary to produce high quality logs.     

Effect of wide spacing on increment and branch properties of young Norway spruce

The effects of stand density on increment and branch properties were studied in three spacing experiments of Norway spruce [Picea abies (L.) Karst.]. The stand densities ranged from 350 stems ha⁻¹, regarded as open-grown trees, up to 1,600 stems ha⁻¹, corresponding to the density recommended for forestry practice. Properties of all the branches were measured from the stem apex downwards. The study material included a total of 5,661 branches from 45 trees. Increasing stand density resulted in a decrease in radial increment as well as shorter and narrower crowns, but it had no effect on height increment. The average number of spike knots per tree was 0.87, 0.27, and 0.33 in densities of 350, 700 and 1,600 ha⁻¹, respectively. Additionally, in the widely spaced stands of 350 stems ha⁻¹, the fraction of trees having spike knots was high (over 50%). At a density of 1,600 ha⁻¹, the sample trees had somewhat less branches in a whorl compared with the more widely spaced plots. The most pronounced effect of stand density was the increase in branch diameter with decreasing stand density. At a density of 350 ha⁻¹, the maximum branch diameter of all the sample trees exceeded the diameter limit of quality class B in the European quality requirements for round wood. The results give some indication that trees subjected to severe competition would produce smaller branches per unit of crown projection area. However, the possibilities for reducing branch dimensions relative to stem and crown size through competition appear quite restricted.