旱地棉花主要促控措施的产量效应分析

本文根据三年试验结果所建立的数学模型,结合4—9月份的不同降雨量条件,对旱地棉花增加种植密度以后各种促控措施(施(?)量、施磷量、打顶日期、化控日期)的合理定量进行了分析。结果认为:早地棉花的高产栽培方案应以种植密度和磷肥的合理定量为基本內容,氮肥、打顶和化控作为依据天气情况和苗情酌情实施的调节措施。最后,依据试验结果,对方案的可行性及优点进行了讨论。     

Spring Barley Responses to Row Spacing and Fungicide Triadimefon in Regions with a Short Crop-growing Season

Aspects of intensive management practices such as high-yielding cultivars, narrow-row spacings and fungicide treatments could potentially increase cereal yields in regions with a short crop-growing season and occasionally dry and hot weather. A field experiment was carried out at McGill University, Canada for three years (1987 to 1989) to test the effects of triadimefon (1-[4-chlorophenoxy]-3,3-dimethyl-1-[1H-1,2,4-triazol-1-yl]-2-butanone, or Bayleton, a trade name) fungicide (0 vs. 140 g a.i. ha⁻¹) and row spacing (10 vs. 20 cm) on the yield components, yield and other agronomic traits (spike emergence, days to maturity, leaf disease and plant height) of spring barley ( Hordeum vulgare L.) cv. Cadette, Laurier and Leger. A cultivar by row spacing interaction resulted in a 11 to 13.5 % increase in grain yield due to narrow rows for Laurier in two out of the three years and up to 16 % for Leger in one year. Over the three years grain yields were on average increased 6 to 12 % due to use of the narrower row spacing. Fungicide application to barley at the early heading stage effectively controlled leaf diseases without influence on yield components or grain yield. Our results indicate that some components of intensive management such as narrow row spacing can be applicable in regions with a short crop-growing season.     

小黑麦与黑麦花序结构和籽粒特性比较

植物的花序结构及其形态特征是影响种子生产性能的重要因素。对于禾本科植物而言,其花序大小、小穗数、小花数及小花的外稃、内稃和芒的性状特征直接影响种子形成和产量。本研究通过测定小黑麦品系C2、C35和黑麦品系C13、C33的花序结构特征,得到以下结果:小黑麦花序[(14.30±0.52) cm×(1.24±0.09) cm]明显大于黑麦[(13.20±0.35) cm×(0.82±0.02) cm],小黑麦花序长而粗,黑麦花序短而细;小黑麦花序的小穗数[(21.35±1.47)个]少于黑麦[(30.20±0.79)个];小黑麦每个小穗的小花数较多,为3~4朵,黑麦的小花数趋于稳定,每个小穗有2朵小花。从花序中部小穗的小花结构看,小黑麦下位护颖长[(1.27±0.11) cm]和宽[(0.26±0.03) cm]、上位护颖长[(1.30±0.09) cm]和宽[(0.23±0.04) cm]均显著大于黑麦下位护颖长[(1.04±0.05) cm]和宽[(0.08±0.01) cm]、上位护颖长[(0.94±0.10) cm]和宽[(0.06±0.01) cm];小黑麦中部小穗第1小花的外稃宽[(0.32±0.03) cm]、外稃高[(0.24±0.03) cm]和芒长[(8.35±0.51) cm]、第2小花的外稃宽[(0.35±0.04) cm]、外稃高[(0.25±0.05) cm]和芒长[(8.37±1.19) cm]极显著大于黑麦相应值[(0.26±0.01),(0.15±0.01),(5.50±0.19),(0.25±0.01),(0.17±0.01)和(5.18±0.23) cm];第1和第2小花的外稃长[(1.35±0.06),(1.37±0.06) cm]和内稃长[(0.84±0.04),(1.41±0.06) cm]均小于黑麦的外稃长[(1.49±0.05),(1.47±0.05) cm]和内稃长[(1.45±0.05),(1.47±0.04) cm]。小黑麦的穗粒数[(52.50±1.80)粒]显著低于黑麦[(58.50±2.50)粒] (P<0.05),但其穗粒重[(2.08±0.04) g]、粒重[(0.04±0.00) g]和籽粒宽[(3.04±0.32) mm]均极显著高于黑麦 (P<0.01),每个花序的籽粒不仅体积大,而且质量较重,其籽粒的生产性能高于黑麦。小黑麦籽粒呈椭圆形或长卵圆形,浅黄色,表皮皱缩,饱满度差;黑麦籽粒呈窄纺锤形,青灰色,表皮光滑,籽粒饱满。小黑麦和黑麦花序结构与籽粒性状的Pearson相关分析表明,小黑麦花序宽和花序基部小穗数与籽粒长显著正相关(P<0.05),花序长与籽粒宽极显著正相关(P<0.01),花序中部小穗的下、上位护颖宽分别与穗粒重和穗粒数极显著正相关(P<0.01);黑麦花序中部小穗第2小花的内稃长与籽粒长显著正相关(P<0.05),外稃高与穗粒数极显著负相关(P<0.01)。研究小黑麦和黑麦的花序结构和籽粒特征,对正确区分二者和了解其籽粒的生产性能具有重要意义,同时有利于小黑麦的示范推广。     

Amino acid profiles of rumen undegradable protein: a comparison between forages including cereal straws and alfalfa and their respective total mixed rations

Optimizing the amino acid (AA) profile of rumen undegradable protein (RUP) can positively affect the amount of milk protein. This study was conducted to improve knowledge regarding the AA profile of rumen undegradable protein from corn stover, rice straw and alfalfa hay as well as the total mixed ratio diets (TMR) based on one of them as forage source [forage‐to‐concentrate ratio of 45:55 (30% of corn stover (CS), 30% of rice straw (RS), 23% of alfalfa hay (AH) and dry matter basis)]. The other ingredients in the three TMR diets were similar. The RUP of all the forages and diets was estimated by incubation for 16 hr in the rumen of three ruminally cannulated lactating cows. All residues were corrected for microbial colonization, which was necessary in determining the AA composition of RUP from feed samples using in situ method. Compared with their original AA composition, the AA pattern of forages and forage‐based diets changed drastically after rumen exposure. In addition, the extent of ruminal degradation of analysed AA was not constant among the forages. The greatest individual AA degradability of alfalfa hay and corn stover was Pro, but was His of rice straw. A remarkable difference was observed between microbial attachment corrected and uncorrected AA profiles of RUP, except for alfalfa hay and His in the three forages and TMR diets. The ruminal AA degradability of cereal straws was altered compared with alfalfa hay but not for the TMR diets. In summary, the AA composition of forages and TMR‐based diets changed significantly after ruminal exposure, indicating that the original AA profiles of the feed cannot represent its AA composition of RUP. The AA profile of RUP and ruminal AA degradability for corn stover and rice straw contributed to missing information in the field.     

The mechanical roles of the clasping leaf sheath in cereals: Two case studies from oat and wheat plants

Stem lodging is a common problem in cereal crop production and a main constraint for grain yield improvement. The leaf sheath that surrounds and protects the hollow internodes of stem could provide the plants with a great physical support. However, this biomechanical function has been ignored for several decades in cereal crops. This study aimed to examine the biomechanical properties of basal stem internodes and lodging susceptibility of the whole plants with or without the clasping leaf sheath in wheat (Triticum aestivum L.) and oat (Avena sativa L.) among different genotypes and agronomic practices (including planting densities and nitrogen application rates). The main objective was to quantify the mechanical role of the leaf sheath in oat and wheat crops by a “safety factor” method. On average, the leaf sheath contributed 40%, 68% and 38% of the overall stem bending strength, flexural rigidity and safety factor, in oat, while it accounted for 11%, 24% and 10%, respectively, in wheat plants. The significant contribution of the leaf sheath is due to its vital role in enlarging the peripheral position (i.e., second moment of area) and stiffness (i.e., Young's modulus). The contribution ratios (%) were found to be higher in oat than in wheat plants, due to the greater mass density of leaf sheath and more proficient/prevailing stay-green capability in oat genotypes. This study emphasizes the important mechanical role of clasping leaf sheath on stem internodes of cereals and indicates that the stay-green trait of the leaf sheath can be exploited to design appropriate varieties with improved lodging resistance and great yield potential.     

Effect of conservation agriculture on soil organic and inorganic carbon sequestration and lability: A study from a rice–wheat cropping system on a calcareous soil of the eastern Indo-Gangetic Plains

Increasing soil carbon (C) in arable soils is an important strategy to achieve sustainable yields and mitigate climate change. We investigated changes in soil organic and inorganic carbon (SOC and SIC) under conservation agriculture (CA) in a calcareous soil of the eastern Indo-Gangetic Plains of India. The treatments were as follows: conventional-till rice and wheat (CT-CT), CT rice and zero-till wheat (CT-ZT), ZT direct seeded rice (DSR) and CT wheat (ZT-CT), ZTDSR and ZT wheat without crop residue retention (ZT-ZT), ZT-ZT with residue (ZT-ZT+R), and DSR and wheat both on permanent beds with residue (PB-PB+R). The ZT-ZT+R had the highest total SOC in both 0–15 and 15–30 cm soil layers (20% and 40% higher (p < .05) than CT-CT, respectively), whereas total SIC decreased by 11% and 15% in the respective layers under ZT-ZT+R compared with CT-CT. Non-labile SOC was the largest pool, followed by very labile, labile and less labile SOC. The benefits of ZT and residue retention were greatest for very labile SOC, which showed a significant (p < .05) increase (~50%) under ZT-ZT+R compared with CT-CT. The ZT-ZT+R sequestered ~2 Mg ha⁻¹ total SOC in the 0–15 cm soil layer in 6 years, where CT registered significant losses. Thus, the adoption of CA should be recommended in calcareous soils, for C sequestration, and also as a reclamation technique.     

盐渍化土壤覆土材料理化性状及其对双孢蘑菇生长的影响

研究山西省当地盐渍化土壤添加草炭土、醋糟、谷糠或高粱壳配制的不同覆土材料(Ⅰ:66.7%草炭土,33.3%盐渍化土壤;Ⅱ:50%草炭土,50%盐渍化土壤;Ⅲ~Ⅴ:每立方米盐渍化土壤分别添加45kg醋糟、谷糠或高粱)的理化性状,并比较不同覆土材料对双孢蘑菇(Agaricus bisporus)生长的影响,以草炭土为对照。从覆土至第一潮菇采收结束,Ⅰ和Ⅱ覆土电导率呈逐渐上升趋势,而Ⅲ~Ⅴ覆土的电导率则一直保持较高水平,为1427~1980μS/cm,第三潮菇采收时,Ⅰ~Ⅴ覆土电导率均显著下降;覆土第6天开始,Ⅰ~Ⅴ覆土的pH明显高于对照,为7.47~8.47;Ⅰ和Ⅱ覆土处理的发菌天数与对照相同,Ⅲ~Ⅴ覆土处理则比对照延长3d;各处理的第一潮菇和第三潮菇的采收时间均为5d,第二潮菇采收时间各处理间略有差异,但总产量均高于对照,其中以Ⅲ覆土处理产量最高,达21.3kg/m~2。试验结果表明,盐渍化土壤添加草炭土、醋糟、谷糠或高粱壳均可作为生产双孢蘑菇的覆土材料。     

北方旱作区小流域截潜流集水高效利用研究

论述了北方旱作区寿阳白马河流域截潜流集水工程的结构和功能特点,研究了截潜流集水效果和高效利用技术的途径和措施。为北方同类型区域综合利用区域水资源提供参考。     

Managing secondary dryland salinity: Options and challenges

Salt occurs naturally at high levels in the subsoils of most Australian agricultural land. As a result of clearing native vegetation, groundwater tables have risen, mobilising the stored salt and causing adverse impacts on farmland, infrastructure, water resources, and biodiversity. The main action required to prevent groundwater tables from rising is establishment of perennial plants, either herbaceous (pastures or crops) or woody (trees and shrubs). Recent technical and economic research has emphasised how difficult it will be to establish sufficient perennials to get control of groundwater tables. Where watertables are already shallow, the options for farmers are salt-tolerant plants (e.g. saltbush for grazing) or engineering (e.g. deep open drains). The existing options for farm-level salinity management are reviewed, with mixed but somewhat disappointing findings regarding their suitability for addressing salinity. However, there are also a number of good prospects for development of new and better options for plant-based management of salinity, and these are described.