Independent and Combined Effects of High Temperature and Drought Stress During Grain Filling on Plant Yield and Chloroplast EF‐Tu Expression in Spring Wheat

High temperature and drought stress are among the two most important environmental factors influencing crop growth, development and yield processes. These two stresses commonly occur in combination. Objectives of this research were to investigate the independent and combined effects of high temperature and drought stress during grain filling on physiological, vegetative and yield traits and expression of a chloroplast protein synthesis elongation factor (EF‐Tu) of wheat (Triticum aestivum L.). Two spring wheat cultivars (Pavon‐76 and Seri‐82) were grown at control temperatures (CT; day/night, 24/14 °C; 16/8 h photo/dark period) from sowing to heading. Thereafter, one half of the plants were exposed to high temperature stress (HT; 31/18 °C in Exp. 1 and 34/22 °C in Exp. 2), drought stress (withholding water), or a combination of both HT and drought stress. There were significant influences of HT and/or drought stress on physiological, growth and yield traits. There was no cultivar or cultivar by temperature or cultivar by drought interaction effects on most traits. The decreases in leaf photosynthesis were greater at HT compared with drought alone throughout the stress period, and the combination of HT and drought had the lowest leaf photosynthetic rates. Overall, HT or drought had similar effects (about 48–56 % decrease) on spikelet fertility, grain numbers and grain yield. High temperature decreased grain numbers (by 56 % averaged across both experiments) and individual grain weight (by 25 %), while, respective decreases due to drought were 48 % and 35 %. This suggests that the grain numbers were more sensitive to HT and grain weights to drought for the range of temperatures tested in this research. The interaction between HT and drought stress was significant for total dry weights, harvest index and spikelet fertility, particularly when HT stress was severe (34/22 °C). The combined effects of HT and drought were greater than additive effects of HT or drought alone for leaf chlorophyll content, grain numbers and harvest index. High temperature stress and the combination of HT and drought stress but not drought stress alone resulted in the overexpression of EF‐Tu in both spring wheat cultivars.     

Accumulation of Iron, Copper, Manganese and Nickel during Maize Grain Maturation

Dynamics of the accumulation of iron, copper, manganese and nickel, as well as their relationships with total ash, crude proteins and total dry matter during maize grain maturation were investigated. The investigation was carried out on normal maize hybrids grown under the same topographical and agrotechnical conditions. The amounts of particular microelements in the fresh grain matter increased significantly up to a late stage of dough maturation. The dynamics of their accumulation correlated positively and significantly with deposition of total dry matter, total ash and crude proteins, and were consistent with biological needs of the maize grain during development. The amounts of microelements expressed on a dry matter basis decreased significantly in a late stage of milky grain maturation. Further fluctuations were not significant. The correlation between particular microelements during grain maturation was positive and significant, as well as the correlation of particular microelements with crude proteins and total ash in the grain dry matter.     

拟南芥缺铜敏感突变体的鉴定分析

为进一步探明植物缺铜响应机制,利用甲基磺酸乙酯(EMS)诱变、体视显微形态观察和ICP-MS技术对拟南芥(Col)缺铜敏感突变体cds-1进行鉴定分析。结果表明:在缺铜条件下,cds-1的根伸长发育受到抑制,而高浓度铜处理则可使得cds-1根长部分恢复至野生型。除根伸长发育受到抑制外,cds-1根部形态(根毛长度和根直径)与野生型相比也有较大差异。cds-1与野生型植株体内铜含量无显著差异。遗传分析该突变体性状由2对隐性等位基因控制。     

Physiological Changes in Sesbania Species to Reducing Light Intensities

Sesbania sesban and S. grandiflora were studied for their physiological characters under different light intensities (100, 75, 50 and 25 %) in a natural environment for 4 months. Rate of photosynthesis (PN) and stomatal conductance (CS) significantly decreased with decreasing light intensities and with intensity reduced to half the full sun light under high shading i.e. at 25 % light intensity, whereas the intercellular CO₂ concentration increased with decreasing light intensities in both the species. The reduction in PN was more in S. grandiflora than S. sesban. S. sesban maintained higher carboxylation efficiency under shade condition as compared to S. grandiflora. Rate of transpiration and water use efficiency (PN/TR) decreased while leaf diffusion resistance increased significantly with decreasing light intensities. Total chlorophyll content was maximal under 50 % light intensity in both plant species. Accumulation of chl b increased but chl a decreases under low light intensities. The higher accumulation of chl b in S. sesban under shade predicted its shade adaptability. The total protein content and NRA reduced under low light intensities. The overall rate of photosynthesis, stomatal conductance, carboxylation efficiency and water-use efficiency were higher in S. sesban as compared to S. grandiflora , indicating its better adaptability under shade condition and that it may be suitable to grow under stress in agroforestry systems in semi-arid tropics.     

日粮高铜对雏鸡血清免疫球蛋白含量的影响

选用1日龄艾维茵肉鸡健雏420只,随机分为7组,分别喂以对照日粮(Cu11mg/kg)和高铜日粮(Cu100mg/kg,高铜Ⅰ组;Cu200mg/kg,高铜Ⅱ组;Cu300mg/kg,高铜Ⅲ组;Cu400mg/kg,高铜Ⅳ组;Cu500mg/kg,高铜Ⅴ组;Cu600mg/kg,高铜Ⅵ组)6周。结果显示,高铜Ⅰ、Ⅱ、Ⅲ组雏鸡血清免疫球蛋白含量与对照组比较差异不显著(P>0.05);高铜Ⅳ、Ⅴ、Ⅵ组雏鸡血清免疫球蛋白含量显著降低(P<0.05或P<0.01),并与日粮含铜量呈负相关。结果表明,日粮铜含量在400mg/kg及其以上可抑制免疫球蛋白的合成,导致雏鸡体液免疫功能受损。     

Chlorophyll Stability is an Indicator of Drought Tolerance in Peanut

Chlorophyll stability during drought might be a promising criterion for selection for drought resistance in peanut. The study describes two field trials conducted at Khon Kaen University, Thailand which investigate genotype × drought interactions in a wide range of peanut germplasm in general and assess the relationship between chlorophyll stability and genotypic performance in particular, under drought. Two field experiments (during 2003/2004 and 2004/2005 dry seasons) were conducted in a split plot design with three water regimes [field capacity, 2/3 available water (AW) and 1/3 AW] as main, and 12 peanut genotypes as subtreatments, replicated four times. Observations on total dry matter (TDM), chlorophyll density (ChlD) (chlorophyll content per unit leaf area), chlorophyll content (chlorophyll content per plant) and SPAD chlorophyll meter readings (SCMR) were recorded at 30, 60 and 90 days after emergence. Transpiration (T) and transpiration efficiency (TE) were computed using the data on amount of water input and TDM. Drought stress significantly reduced TDM, T and chlorophyll content across genotypes but significantly increased TE and ChlD in peanut. However, there were significant differences among genotypes for TE and chlorophyll parameters. The genotype × drought interaction effects for chlorophyll characters (content and density) were not significant suggesting a strong genetic effect. The correlation coefficients between TDM and chlorophyll content (r = 0.51, P = 0.01 to r = 0.91, P = 0.01) and between TE and ChlD (r = 0.46, P = 0.05 to r = 0.77, P = 0.01) were positive and significant. These findings suggest that chlorophyll parameters are strongly linked with drought tolerance in peanut. There were highly significant and positive relationships between ChlD and SCMR (r = 0.67, P = 0.01 to r = 0.93, P = 0.01), between SCMR and TE (r = 0.41, P = 0.05 to r = 0.80, P = 0.01) suggesting that SCMR could be used as a tool for rapid assessment of relative chlorophyll status in peanut genotypes as well as for the indirect selection of drought tolerance in peanut.     

Effect of Organically Complexed Copper,Iron, Manganese,and Zinc on Broiler Performance,Mineral Excretion,and Accumulation in Tissues

Supplementation of trace minerals with a large safety margin in broiler chickens has resulted in a high level of mineral excretion that ends up in the environment. Organically complexed trace minerals (organic minerals) may be able to replace the inorganic trace minerals, because the former appear to have a greater bioavailability. Therefore, a 29-d cage study that included diets with supplemental trace minerals from organic and inorganic sources based on a trace mineral deficient control diet was conducted to examine the possible response of broiler chickens to organic mineral supplements. The results showed that supplementation with 4 mg of Cu and 40 mg each of Fe, Mn, and Zn from organic sources may be sufficient for normal broiler growth to 29 d of age. It is possible to use these lower levels of organic trace minerals in broiler diets to avoid high levels of trace mineral excretion.