外源激素和糖类对玉米zSs1表达的影响

为明确外源激素和糖类对叶片zSs1表达的影响,本文以玉米优良自交系18-599叶片为材料,在分别含有甘露醇、蔗糖、葡萄糖的培养基中处理,然后分别添加ABA、GA,提取总RNA,通过Real-time PCR检测zSs1基因mRNA表达量变化.结果表明:与只含基础盐处理相比,单独用甘露醇和葡萄糖处理玉米叶片,zSs1基因...     

Carbohydrates in fish nutrition: effects on growth, glucose metabolism and hepatic enzymes

The utilisation of dietary carbohydrates and their effects on fish metabolism are reviewed. Details on how dietary carbohydrates affect growth, feed utilisation and deposition of nutrients are discussed. Variations in plasma glucose concentrations emphasizing results from glucose tolerance tests, and the impact of adaptation diets are interpreted in the context of secondary carbohydrate metabolism. Our focus then shifts to selected aspects of hormonal regulation of carbohydrate metabolism and dietary carbohydrates and their variable effects on glycogen and glucose turnover. We analyse the interaction of carbohydrates with other nutrients, especially protein and protein sparing, and de novo synthesis of lipids, and finish by discussing the correlation of dietary carbohydrates with fish health.     

Some Morpho-Physiological Characteristics of Mung Bean Mycorrhizal Plants under Different Irrigation Regimes in Field Condition

In this study we determined some morpho-physiological characteristics of mung bean plants under various irrigation regimes (irrigation after 50, 100, 150 and 200 mm evaporation from pan class A) and mycorrhizal fungi inoculation (Glomus mosseae, Glomus intraradices). The highest and lowest seed yield was obtained from plants irrigated after 50 and 200 mm evaporation from pan, respectively. Root dry weight, root volume, leaf phosphorus and relative water content were decreased in plants under water deficit stress. Whereas, under various level of severe water deficit the proline content, total soluble carbohydrates and leaf nitrogen were increased. Mycorrhizal colonization was observed to be higher in well-watered plants rather than in stressed plants. Furthermore, the mycorrhizal plants produced a higher seed yield (161 g/m²), leaf phosphorus, leaf nitrogen, chlorophyll index, proline, total soluble carbohydrates content, relative water content, root length, root volume, root dry weight and root/shoot weight ratio as compared with non-mycorrhizal plants.     

Nitrogen fertilizer application and developmental stage affect silage quality of timothy (Phleum pratense L.)

Crop composition at harvest affects the ensiling process and the resulting silage quality. The objectives of this study were to determine: (i) the effect of annual N‐fertilizer application (0, 60, 120 and 180 kg N ha^?1) and developmental stage (stem elongation, early heading, late heading and early flowering) on the ensiling properties and silage quality of the spring regrowth of timothy (Phleum pratense L.) at two sites for 1 or 2 years, and (ii) the relationship between ensiling properties of the forage and the quality of the resulting silage. Laboratory silos with wilted forage at approximately 350 g dry matter (DM) kg^?1 of fresh matter were prepared at each harvest and opened 150 d later for silage analysis. Higher rates of N‐fertilizer application decreased the concentration of water‐soluble carbohydrates (WSC), increased the buffering capacity (BC) and nitrate concentration, and decreased the ratio of WSC:BC, primarily in the early stages of development. The ensiling properties of timothy were, therefore, less favourable when high rates of N fertilizer were applied. Silage pH generally increased with increasing rates of N‐fertilizer application; this increase was particularly evident at the first three developmental stages at one site in 1 year. Non‐protein N (NPN) and soluble N concentrations of the silages increased with increased rates of N‐fertilizer application at the first three developmental stages but decreased at early flowering. Ammonia‐N concentration in the silages increased by 0·85, 0·56 and 0·67 when rates of N‐fertilizer application were 60, 120 and 180 kg ha^?1, respectively, compared with that when no N fertilizer was applied. Significant correlations between the composition of the forage ensiled and silage quality variables were found at sites in individual years but, when all data were combined, WSC concentration and BC, and their ratio in the forages, were not correlated with pH, and soluble‐N and ammonia‐N concentrations of the silages, and were weakly correlated with NPN and free amino acid‐N concentrations of the silages. Silage quality was reduced by increased N‐fertilizer application, primarily at the early developmental stages, and this can be attributed to a reduction in WSC concentration and an increase in BC of the forage. Water‐soluble carbohydrate concentration, BC, and their ratio, however, were poor predictors of silage quality.     

Available carbohydrates of cereal grains as affected by storage and insect infestation

Total soluble sugar, reducing sugar, non-reducing sugar and starch contents of wheat, maize and sorghum grains were affected adversely at 25, 50 and 75% insect infestation caused byTrogoderma granarium Everts andRhizopertha dominica Fabricius, separately and mixed population.R. dominica caused significant (P<0.05) reduction in available carbohydrates at 50 and 75% infestation levels whereasT. granarium achieved similar effect at 75%. Mixture of both insect species caused intermediate losses. Storage of cereal grains up to 4 months resulted in substantial increase in sugars and decrease in starch content, but storage for a shorter period of time did not cause any significant changes in levels of carbohydrates.     

温带12个树种新老树枝非结构性碳水化合物浓度比较

非结构性碳水化合物(NSC)是树木存活的重要碳储备。以温带12个树种(红松、樟子松、红皮云杉、兴安落叶松、蒙古栎、春榆、水曲柳、胡桃楸、山杨、大青杨、白桦和紫椴)为对象,在不同物候期取样7次以比较新枝和老枝的NSC浓度的季节动态,分析新枝和老枝的可溶性糖和淀粉浓度的关系,探索引起树枝NSC种间差异的原因。结果表明:除了山杨和大青杨之外,其它树种的新枝和老枝NSC浓度具有相似的季节动态,且新枝NSC浓度普遍高于老枝。常绿树种发芽前老枝TNC(总非结构性碳水化合物,即糖和淀粉之和)浓度快速上升,发芽后TNC变化较小,秋季TNC略有回升。落叶树种展叶前多数树种老枝TNC浓度下降;完全展叶后新枝和老枝TNC浓度均逐渐升高;秋季新枝和老枝的TNC大量积累,在休眠季节部分淀粉转化为可溶性糖。所有树种的新老枝中可溶性糖和淀粉均具有显著的线性关系;而可溶性糖、淀粉和TNC在新枝和老枝之间也均有显著的相关性。除了红皮云杉、春榆(缺乏数据)和蒙古栎(夏季出现两次生长)之外,其它9个树种老枝的TNC浓度的季节平均值、最大值和储存能力均随枝长生长期的延长而显著下降,说明枝长生长期与TNC存储功能之间相关联。     

Carbohydrate dynamics in roots,stems, and branches after maintenance pruning in two common urban tree species of North America

The ability of plants to tolerate stress is determined in part by the carbon allocated to their reserves. We studied two common urban tree species in northeastern North America, Acer saccharinum (Silver maple, native) and Acer platanoides (Norway maple, exotic), to assess the dynamics of non-structural carbohydrate (NSC) concentrations immediately following a maintenance pruning of 30% of the tree crown. NSC concentrations were measured by high-performance liquid chromatography in branches, main stems, and root tissues for both pruned and un-pruned trees at three intervals during the growing season. NSC concentrations in tree organs of A. platanoides were 75% higher than in A. saccharinum. Maintenance pruning did not have any significant depletion effect on carbohydrate concentrations in the tissues of either species. Yet, there was a significant increase in the NSC concentrations in un-pruned branches of pruned trees of A. platanoides at the end of the growing season, but no effect was observed in A. saccharinum. Higher levels of carbohydrates after pruning in woody plant tissues suggested that A. platanoides may have compensatory mechanisms that allow this species to respond better to maintenance pruning than A. saccharinum.     

Tolerance to frost and ice encasement in cultivars of timothy and perennial ryegrass during winter

Ice encasement causes major winter damage in grasslands in coastal areas of Northern Scandinavia and may also affect grass performance in a future changing climate. Changes in ice‐encasement tolerance (LD50), frost tolerance (LT50) and water‐soluble carbohydrate (WSC) content were investigated in different cultivars of timothy and perennial ryegrass sampled at three sites with contrasting conditions. Timothy endured ice encasement for 40 d more than ryegrass (maximum LD50 63 vs. 20 d), and a cultivar originating from 69°N tolerated significantly longer periods in ice than a cultivar from 59°N. A similar relationship between cultivar origin and tolerance was observed for ryegrass. The higher LD50 in timothy compared with ryegrass seemed to be associated with a lower rate of change in WSC content during ice encasement, but no apparent relationship was found between WSC content at the start of encasement and plant survival in ice. A significant linear relationship was found between LD50 and LT50 of plants sampled in the field. A differing decline in frost tolerance during ice encasement for the species indicated that timothy is more resistant to dehardening under ice than ryegrass. This study contributes data and functional relationships needed to develop models of grass performance during winter.     

Impact of cutting frequency on the vigour of Rumex obtusifolius

The control of Rumex obtusifolius, even with the use of herbicides, is difficult in permanent grasslands where R. obtusifolius reduces both productivity and nutritive value of herbage. It is important to find alternative approaches to managing R. obtusifolius. Two greenhouse experiments were conducted to compare the impact of different cutting frequencies, which simulated grazing (three cuts), silage making (two cuts) and hay making (one cut) on shoot and root measurements of the vigour of R. obtusifolius. In both experiments the same cutting frequencies were imposed but in Experiment 1 the treatments were imposed for 2 years and in Experiment 2 for 1 year. Compared to the silage‐making and hay‐making treatments, there was a reduction in the vigour of the aerial parts of R. obtusifolius on the grazing treatment, associated with a reduction in the number of leaves (Experiment 1), in the size of the largest leaf (Experiment 1) and in the herbage mass of dry matter (Experiments 1 and 2). Roots had higher concentrations of total soluble sugar and lower concentrations of starch in the grazing treatment than in the other treatments. These results showed that a reduction in the vigour of R. obtusifolius in permanent grasslands is possible only if the plants are submitted to a high frequency of defoliation under cutting or grazing.     

粉状富淀粉传统保健食材碳水化合物体外消化特性

探讨焙烤后打粉冲糊方法对富淀粉保健食材碳水化合物消化特性的影响。采用体外模拟消化方法测定各样品快消化淀粉、慢消化淀粉和抗性淀粉的含量及水解率,并对淀粉糊化温度、糊化度等进行研究。试验结果表明：冲糊水量和温度显著影响样品的水解速率和淀粉类型,增加沸水量可使所有样品的水解指数超过蒸煮处理水平,蒸煮处理山药干、芡实、莲子、薏米和红小豆血糖负荷评估值分别为47．38、42．28、29．05、42．79和28．96;沸水量大冲糊方法的血糖负荷评估值分别为51．80、55．49、50．19、50．93和40．26。控制冲糊方法或可有效控制粉状淀粉食材的消化速度和淀粉类型比例,为不同生理状况的人群控制其血糖反应提供可能性。