Water-use efficiency and physiological responses of maize under partial root-zone irrigation

Alternate partial root-zone irrigation (APRI) is a water-saving irrigation method but also can regulate crop physiological responses. This study investigated how water-use efficiency (WUE) and other physiological responses were regulated at different growth stages when maize plants were applied with APRI and how these responses were recovered to control levels when full irrigation was resumed. A pot experiment was carried out at two fertilization levels and with three irrigation methods at the jointing stage (29-38 days after sowing) or during the jointing and tasselling stages (29-77 days after sowing). The irrigation methods included the conventional irrigation (CI), APRI and fixed PRI (FPRI, watering was fixed to one side). Compared to the CI, APRI at the jointing stage for 10 days or during the jointing and tasselling stages for 49 days reduced water consumption by 10.6-12.9 and 31.7-32.4%, respectively, but did not reduce total dry mass accumulation significantly, thus increased canopy WUE by 10.4-13.6 and 41.2-41.8%, respectively. FPRI reduced the total dry mass significantly even though it also improved canopy WUE. APRI had slight effect on the leaf relative water content (RWC), chlorophyll (Chl), carotenoid (CAR), proline (Pro) and malondialdehyde (MDA) contents and superoxide dismutase (SOD) and peroxidase (POD) activities from jointing to tasselling stages but recovery to the levels of CI was rapid after receiving full watering. In comparison, FPRI treatment significantly reduced leaf RWC, Chl and CAR contents and SOD and POD activities and increased the Pro and MAD contents. After receiving full watering, the above-mentioned physiological indexes in FPRI could not recover fully to the levels of CI. High fertilization treatment only increased leaf Chl content significantly and contributed little to the total dry mass accumulation. Our result suggests that APRI can make plants use water and nutrients more efficiently with better drought tolerance.     

Assessing yield optimization and water reduction potential for summer-sown and spring-sown maize in Pakistan

Agricultural food production in arid and semi-arid regions faces the challenge to ensure high yields with limited supply of water. This raises the question to which extent irrigation supply can be reduced without detriment to yield. Our study focuses on the yield-water uptake relationship for maize in the moderate water stress range in order to determine the onset of stress-induced dry-matter and yield losses. Compensatory plant responses under moderate stress levels are discussed in relation to seasonal climatic conditions.Summer-sown and spring-sown maize were irrigated with a decreasing amount of water in a field experiment in Pakistan. Water supply ranged from 100% water required to maintain soil at field capacity (FC) to 40% of FC. The average dry-matter and yield levels were slightly higher for summer-sown (15.0 Mg ha⁻¹) compared to spring-sown maize (13.1 Mg ha⁻¹). The onset of significant dry-matter and yield reduction started at the least irrigation treatment in both seasons. The amount of water required to avoid production losses was 272 mm in the summer-sown maize during the autumn growing season, and 407 mm for the spring-sown maize in the summer season, when the evaporative demand of the atmosphere was +27% higher. Water use efficiency (WUE_ET), normalized by vapour pressure deficit, of the summer-sown maize which was 10.0 kg kPa m⁻³, was +15% higher compared to the spring-sown crop; while the irrigation water productivity (2.9 kg m⁻³) was +11% more. WUE_ET increased over the whole range of applied water deficits for summer-sown maize, while the spring-sown crop showed a decreasing WUE_ET in the less irrigated treatment. Due to the higher efficiency in summer-sown maize, the potential in irrigation reduction without production losses (129 mm) was higher compared to the spring-sown maize (57 mm). Our results showed that in Pakistan water saving irrigation practices can be applied without yield loss mainly during the cooler growing season when the crop can efficiently compensate a lower total water uptake by increased use efficiency. For spring-sown maize the increasing evaporative demand of the atmosphere towards summer implies a higher risk of yield losses and narrows the range to exploit higher irrigation water productivity under moderate water deficit conditions.     

不同杉木优良品种苗期生长对比试验

以8个杉木优良品种为研究对象开展苗期对比试验。对苗高、地径、高径比及苗木质量分级的分析结果表明、参试杉木优良品种播种品质优良,苗木生长良好,质量高。苗高、地径、高径比在各品种苗木间差异性达到极显著或显著水平,现行杉木育苗措施并不适用于所有杉木良种,应加以改进或加强。     

应用体外消化法评定不同生育期麦类作物营养价值

试验旨在探讨澳大利亚东南部玛瑞达令河沿岸平原地区小麦、青稞和燕麦这3种主要冬季麦类作物在不同生育期的营养价值变化规律.通过近红外光谱分析法测定这3种麦类作物在拔节期、扬花期和灌浆期的主要营养成分和体外消化率.结果表明:生长期对麦类作物的营养价值有显著影响;拔节期的CP含量、DMD、OMD显著高于扬花期(P＜0.05)和灌浆期(P＜0.05);而拔节期的NDF和ADF含量虽然与扬花期和灌浆期无显著差异(P＞0.05),但还是比后者含量要低.综上所述,拔节期的营养价值高于扬花期和灌浆期,建议作为饲草种植的冬播麦类作物的收获期以拔节期为宜.     

河北省冀中地区苹果绵蚜越冬状况研究

为了掌握苹果绵蚜在河北省冀中地区的越冬特点,为其针对性防治措施的实施提供理论依据,2012~2014年对河北省冀中地区苹果绵蚜的越冬场所和越冬虫态进行了调查。结果表明:河北省冀中地区苹果绵蚜在12月进入越冬期,翌年3月开始活动;越冬场所以苹果树根部为主,适宜年份也见于主干和枝条上;越冬虫态以1龄若虫为主,适宜年份见少量的2龄若虫。     

Tolerance of Strawberry Cultivars to Terbacil

Field experiments were conducted to evaluate the tolerance of strawberry cultivars to terbacil. Treatments (84, 168, and 336 g ha^–1) were applied at either dormant stage or 3–4 leaf. Initial crop injury at 1 and 3 weeks after treatment (WAT) ranged between 0% and 43%; all cultivars fully recovered at 6 WAT. Terbacil applied at 168 g ha^–1 at dormant stage caused approximately 20% yield reduction in ‘Brunswick’, ‘Darselect’, and ‘Honeoye’, which was not observed with other treatments. A negative impact of the herbicide on yield of these cultivars is an unlikely outcome when sprayed at 3–4 leaf stage.     

芹菜和结球莴苣春夏季设施幼苗主要生长指标与有效积温研究

以芹菜品种文图拉(西芹)和结球莴苣品种铁人为试材,测定不同苗龄芹菜、结球莴苣幼苗的生长指标及生理指标,研究芹菜和结球莴苣幼苗的生长规律及与有效积温之间的关系。结果表明:芹菜幼苗前期生长缓慢,四叶期后生长速度加快;结球莴苣幼苗子叶期至四叶期快速生长,之后趋缓。芹菜幼苗的叶绿素SPAD值、POD活性呈持续增长的态势,根系活力、CAT活性生长后期趋于平稳;结球莴苣幼苗的叶绿素SPAD值、根系活力、POD活性均呈先增加后降低的趋势,CAT活性先小幅下降、后持续增长,SOD活性出现两次高峰。芹菜育苗阶段的有效积温为949.0℃·d,子叶期和五叶期增幅较大;结球莴苣育苗阶段的有效积温为502.9℃·d,各时期增长平稳。综上,芹菜幼苗适宜的定植时期为四叶期,结球莴苣幼苗适宜的定植时期为五叶期。     

湖北长阳山区萝卜根肿病抗性鉴定筛选

长阳山区是湖北高山地区主要的根肿病病区。以100份萝卜种质资源为材料,分别在长阳胡家坪和火烧坪进行根肿病田间成株期抗病性鉴定和苗期人工接种抗病性鉴定。综合成株期和苗期鉴定结果,筛选出抗根肿病种质资源13份,其中白皮萝卜8份(富源1号、华绿8号萝卜、重庆冰糖圆白、春不老、玉堂春、汉白玉、春玉和短叶13号),红皮萝卜3份(红罐、南京红和大红袍),绿皮萝卜2份(灌糖青和德日2号)。利用长阳火烧坪根肿病病圃田间鉴定了155个萝卜杂交组合,筛选出抗根肿病优良组合3个。     

钼肥对甘蓝型油菜薹期碳氮代谢的影响

为了解钼肥施用对甘蓝型油菜薹期钼营养及叶片碳氮代谢的影响,采用盆栽试验,测定了甘蓝型油菜各个部位钼含量,叶片光合特性、色素、可溶性糖、游离氨基酸和可溶性蛋白含量。结果表明,施钼显著增加2个品种L0917和中双11(ZS11)单株鲜质量,提高幅度分别为235.50%,67.94%。施钼显著提高了ZS11叶片色素含量,L0917和ZS11叶绿素a/b值,分别降低了16.28%和10.26%,施钼提高了蒸腾速率(Tr),降低了胞间CO2浓度(Ci),对光合速率(Pn)和气孔导度(Gs)没有显著影响。同时,施钼提高了可溶性糖、游离氨基酸和可溶性蛋白含量,提高幅度分别为(L0917和ZS11)35.31%和91.38%,83.57%和274.30%,16.81%和16.02%。施钼提高了叶片硝酸还原酶(NR)的活性,L0917和ZS11提高幅度分别为211.50%,335.80%。施钼分别提高了甘蓝型油菜薹期根、茎秆和叶部位钼含量。薹期碳氮代谢研究及钼营养诊断为甘蓝型油菜花期和成熟期生殖和营养生长提供理论依据。     

Genetic Variation for Salinity Tolerance in Pakistani Rice (Oryza sativa L.) Germplasm

Soil salinity is one of the major production constraints. Development and planting of salt‐tolerant varieties can reduce yield losses due to salinity. We screened 185 rice genotypes at germination stage in petri dishes under control, 50, 100 and 150 mm salt stress, and at seedling stage in Yoshida's hydroponic nutrient solution under control, 50 and 100 mm salt stress. At germination stage, 15 genotypes including Nona Bokra, Sonahri Kangni, 7421, 7423 and 7467, whereas at seedling stage, 28 genotypes including Nona Bokra, Jajai‐77, KSK‐133, KSK‐282, Fakhr‐e‐Malakand, Pakhal, IR‐6, Khushboo‐95, Shahkar and Shua‐92 were found salt tolerant. Basmati‐370, Mushkan, Homo‐46 and accessions 7436, 7437 and 7720 were sensitive to salinity at both germination and seedling stage. We further screened a subset of 33 salt‐tolerant and salt‐sensitive genotypes with SSR markers. Four SSR markers (RM19, RM171, RM172 and RM189) showed significant association with two or more of the studied traits under 50, 100 and 150 mm salt stress. These markers may be further tested for their potential in marker‐assisted selection. The salt‐tolerant genotypes identified in this study may prove useful in the development of salt‐tolerant rice varieties in adapted genetic background.