Glycine max and Glycine soja are capable of cold acclimation

Soybean has been considered a cold intolerant species; based largely upon seed germination and soil emergent evaluations. This study reports a distinct acquisition of cold tolerance, in seedlings, following short acclimation periods. Diversity in cold responses was assessed in eight cultivars of Glycine max and six accessions of G. soja. All varieties of soybean significantly increased in freezing tolerance following acclimation. This study indicates soybean seedlings are indeed capable of sensing cold and acquiring cold tolerance. Germination rates after cold imbibition were negatively correlated with maturity group, but positively correlated with cold acclimation potential in G. soja. Seed fatty acid composition was varied between the species, with Glycine soja accessions containing about 2‐times more linolenic acid (18:3) than G. max. Furthermore, high levels of linoleic acid (18:2) in seeds were positively correlated with germination rates following cold imbibition in G. soja only. We suggest that domestication has not impacted the overall ability of soybean to cold acclimate at the seedling stage and that there is little variation within the domesticated species for ability to cold acclimate. Thus, this brief comparative study reduces the enthusiasm for the “wild” species as an additional source of genetic diversity for cold tolerance.     

Evaluating a multi-level subsurface drainage system for improved drainage water quality

This paper describes a multi-level drainage system, designed to improve drainage water quality. Results are presented from a field scale land reclamation experiment implemented in the Murrumbidgee Irrigation Area of New South Wales, Australia. A traditional single level drainage system and a multi-level drainage system were compared in the experiment in an irrigated field setting. The single level drainage system consisted of 1.8 m deep drains at 20 m spacing. This configuration is typical of subsurface drainage system design used in the area. The multi-level drainage system consisted of shallow closely spaced drains (3.3 m spacing at 0.75 m depth) underlain by deeper widely spaced drains (20 m spacing at 1.8 m depth). Data on drainage flows and salinity, water table regime and soil salinity were collected over a 2-year period.     

复杂盐碱生态条件的人工模拟及其对羊草生长的影响

将ＮａＣｌ、ＮａＨＣＯ３、Ｎａ２ＳＯ４和ＮａＣｏ３按不同比例混和,模拟出３０种盐度和ＰＨ各不相同的盐碱生态条件,并用以处理并草苗。测定羊草苗的存活率、分蘖数、根戏数及相对生长率等生长指标;分析盐度和ＰＨ对羊草生长失作用及其盯关性。结果表明：３０处处理均匀覆盖了总盐度５０－３５０ｍｍｏｌ／ＬＰＨ７．１４－１０．８１范围内的各处盐碱条件,羊草的各项生长指标均随盐浓度及Ｐ增高而下降;单纯高ＰＨ域盐度对羊     

Pre-stocking acclimatisation of brown trout Salmo trutta: effects on growth and capture in a fast-flowing river

Abstract  A field experiment was carried out over two consecutive years in a fast-flowing river to evaluate the effects of a 5-day acclimation period on the subsequent growth and capture of stocked juvenile brown trout, Salmo trutta L. Post-stocking growth of both acclimated and non-acclimated fish remained very poor for at least 44 to 50 days. After this slow start, all fish grew significantly but acclimated trout performed 40.1% better than non-acclimated individuals. However, the better growth did not lead to higher capture rates. Capture success post-stocking was low, regardless of acclimation. Flooding, combined with low fitness of the stocked fish in the first weeks was considered the main reason for the unsatisfactory stocking success. It was concluded that in-stream acclimation aids rapid adaptation of stocked trout and thus imparts some growth advantages, although this does not necessarily result in higher yields.     

Photosynthetic Apparatus Responses to Short‐term low‐temperature Flooding May Contribute to Freezing Tolerance Changes in Forage Grasses

Winter conditions are subjected to rapid climate changes. Increased precipitation and snow melting during warmer winters may result in low‐temperature flooding. These factors probably affect plant overwintering strategies. This study investigated the relationships between the photosynthetic adjustment and freezing tolerance following a short‐term low‐temperature flooding in two forage grasses (Lolium perenne and Festuca pratensis). The effect of flooding on the photosynthetic apparatus acclimation to cold was determined using chlorophyll a fluorescence measurements. Freezing tolerance was estimated using an electrolyte leakage test. It has been shown that genotypes activating non‐photochemical mechanisms of photosynthetic acclimation to cold during low‐temperature flooding may show increased freezing tolerance. Freezing tolerance reduction observed in Festuca pratensis was probably connected with decreased photochemical activity and photoinhibition of photosynthesis. It can be concluded that photosynthetic apparatus response to low‐temperature flooding may contribute to changes in the freezing tolerance. The direction of the changes is associated with different photosynthetic apparatus performance.     

Combined effects of salt stress and cucurbit downy mildew (Pseudoperospora cubensis Berk. and Curt. Rostov.) infection on growth,physiological traits and antioxidant activity in cucumber (Cucumis sativus L.) seedlings

Abiotic and biotic stresses both decrease quality and quantity of cultivated plants. We compared responses of Cucumis sativus L. cvs Sardes and Beith alpha which were treated with 50 or 100 mM NaCl and/or infected by Pseudoperospora cubensis Berk. and Curt. Rostov.. Both cultivars were affected remarkably when fungus infection was combined with salt stress however; cv Sardes was found out to be relatively tolerant with sustainable growth performance, better leaf water status and lower lipid peroxidation levels under this condition. This relative tolerance could be related to the fine tuning of the activities of the antioxidative enzymes and proline levels.     

采后黄瓜在冷驯化处理过程中的转录组变化

采后黄瓜是冷敏性果菜类蔬菜，在低温贮藏时易发生冷害。前期研究结果表明，冷驯化处理通过诱导采后黄瓜耐冷性，减少冷害发生。为探究冷驯化处理诱导的转录组学变化，以采后黄瓜为试材，分析冷驯化处理期间的转录组变化。与贮藏前（0 h）相比，在冷驯化处理12 h和72 h时，分别鉴定到1 870和3 550个差异表达基因。基因表达验证结果表明，RT-qPCR和转录组结果高度一致，证明转录组测序数据的准确性和可靠性。GO富集分析结果显示，冷驯化处理诱导的差异表达基因主要富集在氧化还原过程、细胞膜组分和转录因子活性3个GO途径中，表明冷驯化处理通过调节细胞膜组分、细胞内氧化还原状态，增强冷藏黄瓜耐冷性。进一步分析发现，104个转录因子基因响应冷驯化低温，差异表达的转录因子主要是ERF、bZIP、WRKY和HSF家族，表明转录因子介导的转录调控在冷驯化诱导的耐冷性中发挥重要作用。研究结果为采后黄瓜诱导耐冷性提供了新见解，有助于加深对冷驯化诱导耐冷性分子机理的认识，为耐冷黄瓜培育提供了重要基因资源。     

低温驯化的黑荆树悬浮培养细胞中可溶性蛋白质含量变化*

低温驯化能够诱导黑荆树悬浮培养细胞增强抗冻性，ＬＴ５０从－４．３℃下降到－８．２℃。低温驯化诱可溶性蛋白质含量增加，其增加的时间进程与细胞抗冻性发育呈平行关系。环已亚胺抑制可溶性蛋白质含量增加，同时也抑制细胞抗冻性发育。在低温驯化期不同时间加入环已亚胺抑制抗冻性发育，表明低温驯化１０ｄ后抗浆性发育接近完成。糖对增加驯化细胞中可溶性蛋白质有促进作用，加快增加含量的时间进程，但对最终提高蛋白质含量水平     

在低温锻炼中毛白杨幼苗可溶性总蛋白、RNA、DNA、RNase及抗冻性的变化

低温锻炼不仅提高了毛白杨幼苗存活率和抗冻性以及RNA和可溶性总蛋白的含量 ,降低了RNase活性 ,而且能减轻低温胁迫引起的RNA和可溶性总蛋白含量的下降程度和RNase活性的提高 ,有利于幼苗在恢复过程中RNA和可溶性总蛋白水平的迅速回升以及RNase活性的降低 .进一步研究发现 ,DNA含量无论在低温锻炼中还是在低温胁迫下或是在随后的恢复生长期均保持相对稳定 ;低温锻炼所引起的RNA含量的增加 ,与RNase活性的降低呈明显的负相关 ,与可溶性总蛋白含量的增加以及幼苗抗冻性的提高成正相关 .这表明低温锻炼可能抑制RNase活性 ,有效地促进RNA含量的增加 ,而RNA可能参与了可溶性总蛋白的合成及抗冻性的诱导     

Fertilizer-induced Changes in Rhizosphere Electrical Conductivity: Relation to Forest Tree Seedling Root System Growth and Function

Fertilization is standard practice in forest tree seedling nursery culture. Additionally, fertilization at outplanting has potential to facilitate nutrient uptake and reduce transplant shock. Fertilization, however, may dramatically alter rhizosphere chemical properties such as pH, ion availability, and electrical conductivity (EC). These changes may inhibit root system growth and function by reducing soil osmotic potential and creating specific ion toxicities. The risk of root damage associated with high EC levels appears to be dependent on species, age of root system, and soil moisture availability. Root inhibition in container nursery culture of conifers is likely to occur above 2.5 dS m⁻¹, though threshold EC levels for bareroot culture and field plantings are largely unavailable. Fertilization at outplanting has the added risk that drought conditions may prevent leaching of excess fertilizer salts, which can increase rhizosphere EC beyond safe levels and ultimately impair root uptake of water or nutrients. For fertilization programs to be successful, a critical threshold balance must be maintained between optimizing seedling nutrient availability in the rhizosphere, while minimizing potential for root damage. Future research is needed to identify optimal EC levels for a range of species across all stages of the reforestation process, from nursery culture through plantation establishment.