Information extraction and dynamic evaluation of soil salinization with a remote sensing method in a typical county on the Huang-Huai-Hai Plain of China

Monitoring the dynamics of soil salinization is of great importance for agricultural production. This study selected Yucheng County, a typical county on the Huang-Huai-Hai Plain (HHHP) of China, as the study area and evaluated the spatial and temporal variation of soil salinization. Three methods, consisting of principal component analysis (PCA) transformation, tasseled cap (TC) transformation, and optimal band combination (OBC), were used to extract information from an early Landsat multispectral scanner (MSS) image from 1984, and their advantages were compared. In addition, OBC was used on a thematic mapper (TM) image from 2009. An iteratively self-organizing data analysis algorithm was used together with prior knowledge of likely classifications to interpret the MSS and TM images for data classification. Finally, a transfer matrix method was used to assess the spatial and temporal variability of soil salinization and analyze the driving factors of soil salinization. Compared to PCA transformation and OBC, TC transformation was a more effective method for extracting soil salinization information from the MSS sensor. The results indicate that a soil area of approximately 298 km² was affected by salinity in 1984 in Yucheng County, of which 5.40%, 11.96%, and 12.75% were classified as being subject to slight, moderate, and severe salinization, respectively. In 2009, the saline area was reduced to only 146 km², of which 10.70% and 3.75% were characterized by slight to moderate salinization and no severe salinization, respectively. The saline land decreased at an average rate of 6 km² per year. This decrease was probably a result of lower groundwater depth, increased organic fertilizer or crop straw in soil, changed land use type, and increased vegetation coverage.     

水盐交互作用对河套灌区土壤光谱特征的影响

为探究土壤水盐交互作用对Sentinel-2卫星光谱特征的影响，该研究以内蒙古河套灌区沙壕渠灌域为研究区域，分别在2018年和2019年的4-5月共采集280个裸土期表层土壤样本，测定其土壤含水率和含盐量，并获取同步的Sentinel-2卫星遥感数据，构建基于土壤水盐-反射率原理的土壤光谱特征理论模型，在此基础上结合土壤水盐交互作用构建水盐交互模型，并比较2种模型对土壤光谱的模拟效果，分析土壤水盐交互作用对土壤光谱估算的影响。结果表明：1）土壤水盐交互作用对光谱的影响因波段类型和水盐含量的不同而有所不同。在可见光范围上影响相对较弱，其作用范围为-0.11～0.29；在近红外和短波红外范围上影响相对较强，其作用范围为-0.35～0.61；当水分或盐分中某个含量较高时对光谱影响较弱，其主要集中在-0.1～0.23；，在水盐含量程度相似时影响较强，其作用范围为0.3～0.6。2）与土壤光谱特征理论模型相比，水盐交互模型能明显地改善土壤光谱的模拟效果，能将模拟相关系数由0.14～0.44提升到0.29～0.70，均方根误差由0.032～0.082降低到0.029～0.068。该研究结果揭示了盐分和水分对光谱特征的干扰过程，为土壤盐分的估算提供策略与方法，对实现区域尺度上土壤盐分的精准监测具有一定的意义。     

Performance and welfare of Atlantic salmon,Salmo salar L. post-smolts in recirculating aquaculture systems: Importance of salinity and water velocity

Producing a larger post-smolt in recirculating aquaculture systems (RAS) could shorten the production time in sea cages and potentially reduce mortality. Knowledge of the biological requirements of post-smolts in closed-containment systems is however lacking. In the present study, the effects of salinity and water velocity on growth, survival, health, and welfare of Atlantic salmon reared in RAS were examined. Salmon smolts were stocked in three separate RAS with salinities of 12, 22, and 32‰ and subjected to high (1.0 body lengths per s⁻¹) or low (0.3 body lengths second⁻¹) water velocity. Growth performance, survival, welfare, and physiological stress responses were monitored until the fish reached a bodyweight of around 450 g. Growth rate was higher at lower salinity and higher water velocity generally had a positive effect on growth in all salinities. Feed conversion ratio was lower at 12‰ compared to the 22 and 32‰ when the fish were between 250 and 450 g. Higher mortality, elevated plasma cortisol levels, higher incidence of cataract, and a higher expression of stress-induced genes in the skin (iNOS, Muc5ac-like) indicated a negative effect of higher salinity on fish welfare. Male maturation was low (<1%), and not affected by salinity or water velocity.     

Redox halopriming: A Promising Strategy for Inducing Salt Tolerance in Bread Wheat

New strategies to enhance growth and productivity of food crops in saline soils represent important research priorities. This study has investigated the role of certain priming techniques to induce salt tolerance of bread wheat. Wheat grains were soaked in 0.2 mm sodium nitroprusside as nitric oxide donor (redox priming), diluted sea water (halopriming) and the combination of both (redox halopriming). Grains were also soaked in distilled water (hydropriming); in addition, untreated grains were taken as control. Our results indicated that priming treatments significantly improved all growth traits and increased leaf pigments concentration as compared to the control. Priming treatments markedly enhanced membrane stability index, proline, total soluble sugars and K⁺ concentration with simultaneous decrease in the concentration of Na⁺ and malondialdehyde (MDA). Furthermore, yield and yield‐related traits such as plant height, spike length, total number of tillers, 1000‐grain weight, straw and grain yield considerably affected by priming treatments. Moreover, the grain yield of both genotypes was positively affected by redox halopriming treatment. However, the extent of enhancement was more prominent in Gemmiza‐9 (salt sensitive) than that in Sakha‐93 (salt‐tolerant). Overall, this study clearly indicated that redox halopriming treatment is a promising and handy technique to induce salinity tolerance of wheat genotypes.     

Effects of spent mushroom substrates and inorganic fertilizer on the characteristics of a calcareous clayey‐loam soil and lettuce production

We evaluated the effects of the addition of two types of spent mushroom substrate (SMS), SMS from an Agaricus bisporus crop (SMS1) and a mixture of SMSs from an A. bisporus crop and a Pleurotus crop (50% v/v each) (SMS2), on the characteristics of a calcareous clayey‐loam soil and the yield and nutritional status of lettuce (Lactuca sativa L.), relative to crops receiving mineral fertilizer (M) and a control (C) without amendment. The application of SMS, especially SMS1, improved soil fertility compared with C and M soils. Moreover, the use of these organic substrates as soil amendments did not harm the plants and gave yields similar to that obtained with mineral fertilizer. The nutritional contents of the lettuce plants were greater than or similar to those of the plants from treatment C or M, except for the plant tissue concentrations of K, Fe and Zn, which were significantly reduced by SMS application. However, this latter fact did not reduce the lettuce yield in the amended soils. Therefore, the use of SMSs as organic amendments contributes to residue utilization, in an environmentally friendly way, and to improved soil fertility and crop yield.     

Comparison of Salt and Drought‐Stress Effects on Maize Growth and Yield Formation with Regard to Acid Invertase Activity in the Kernels

The long‐term effects of salt stress (11 dS m^?1) and drought stress (35 % WHC) were investigated for two maize genotypes, focusing on the relation between metabolic changes around the time of pollination and the impact on yield determinants at maturity. The relatively salt‐resistant hybrid Pioneer 3906 and the relatively drought‐resistant hybrid Fabregas were compared. The experiments were conducted in large plastic containers in a vegetation hall in two consecutive years (2011 and 2012). Plant height and leaf area were significantly reduced under both stress conditions. The transpiration rate was only slightly reduced under drought stress; but under salt stress, a significant reduction occurred 40–53 days after sowing. As a significant increase in sucrose concentrations was observed in the salt‐treated maize kernels 2 days after pollination, the availability of assimilates was not limiting and the plants could afford to save water by reduced stomatal opening. Although under both stress conditions the soluble acid invertase activity was reduced 2 days after pollination, concomitantly, an increase in hexose concentrations was observed. Thus, in these experiments, the delivery of hexoses by acid invertase activity did not limit kernel development. Differences in grain yield at maturity between salt and drought stress were most likely caused by salt‐specific effects (Na⁺ toxicity), Fabregas being more affected than Pioneer 3906.     

不同盐度下“吉丽”罗非鱼(尼罗罗非鱼♀×萨罗罗非鱼♂)NKCC1a mRNA的组织特异性表达

应用实时荧光定量PCR技术(qRT-PCR),以"吉丽"罗非鱼[尼罗罗非鱼(Oreochromis niloticus,♀)×萨罗罗非鱼(Sarotherodon melanotheron,♂)]为材料,研究NKCCla基因表达的盐度-组织特异性.研究结果表明:(1)NKCCla基因mRNA表达量存在显著的组织特异性,在低于25盐度环境中,NKCCla mRNA在鳃、肝、肾及肠中均有表达;当盐度从0提高到48时,表达量在鳃中与盐度变化呈高度正相关(R＞0.9,P＜0.01),在肠和肾中与盐度变化呈负相关(P≈-0.7,P＜0.05),但在肝中则不受盐度变化的影响.(2)当盐度提高到64,NKCCla基因mRNA表达最在鳃和肠3 h后达最高值,5 h后下降,前后变化差异显著(P＜0.05);表达量在肝中则是在5 h后达最高值,变化差异也显著(P＜0.05);表达量在肾中持续下降,但差异不显著.以上结果揭示,在盐度高于25的环境中,"吉丽"罗非鱼主要由鳃组织的NKCCla排出多余的离子以维持鱼体的水盐平衡,由此认为鳃组织在"吉丽"罗非鱼高渗透压调节中起最主要作用.     

盐度胁迫及昼夜变化对鲻鱼幼鱼消化酶活力的影响

研究了S0（盐度为0）、S10、S20、S33（对照）和S40 5个盐度梯度14d内盐度胁迫及其昼夜变化对鲻鱼（Mugil cephalus）幼鱼蛋白酶和淀粉酶比活力的影响。结果显示：1）盐度胁迫对鲻鱼幼鱼的消化酶活力有显著影响（P〈0．05）。不同盐度的蛋白酶和淀粉酶活力的变化规律都是在第0天～第7天升高，第7天～第14天降低，最终时（第14天）S0～S33蛋白酶活力呈上升趋势，S33～S40下降；S0～S20淀粉酶活力差异不显著（P〉0．05），S20～S33呈上升，S33～S40下降，且差异显著（P〈0．05）；2）对鲻鱼幼鱼消化酶活性昼夜变化的测定表明，蛋白酶和淀粉酶活性的最高值分别在12：00和15：00，最低值均出现在6：00。因此，夜间设置定时投喂，可促进鱼类快速健康生长。     

种子盐引发对转基因抗虫棉耐盐性的影响

以2个转基因抗虫陆地棉品种为材料,以其遗传背景品种为对照,研究种子引发对转基因抗虫棉在NaCl胁迫条件下的种子萌发和田间出苗的影响。结果表明,0.5%的NaCl处理显著地降低陆地棉种子发芽势和发芽率,其中转基因抗虫棉品种(中棉所41和浙905)的种子萌发和田间出苗率差于遗传背景亲本(中棉所23)。种子盐引发处理可以有效地缓解NaCl的胁迫作用,显著地提高种子的发芽势、发芽率和田间出苗率,显著地提高棉花种子的耐盐性。种子盐引发处理对转基因抗虫棉品种的效果优于非转基因抗虫棉的背景品种。引发剂种类对于其耐盐性的影响有一定的差异,以K2SO4的效果更好,且引发剂的浓度与引发时间之间存在着一定的互作效应,高浓度引发剂的处理时间宜短,而低浓度引发剂的处理时间应适当延长。     

Germination of Salicornia bigelovii Ecotypes under Stressing Conditions of Temperature and Salinity and Ameliorative Effects of Plant Growth-promoting Bacteria

Salinity is a major stress condition. Salicornia bigelovii is a valuable edible halophyte, considered to be a promising resource for cultivation in arid coastal zones. Its productivity depends on the supplementary provision of nitrogen, for which an option is chemical fertilization. Nevertheless, indiscriminate use of chemical fertilizers contributes to the problem of increased salinity. The inoculation of plant growth‐promoting bacteria (PGPB) represents an alternative. Seed ecotypes from four coastal areas [Santa Rosa Chica, Santa Rosa Grande, Santa Cruz and Cerro Prieto (CP), Sonora, México] were collected, in order to inoculate them with two species of PGPB (Azospirillum halopraeferens and Klebsiella pneumoniae). Two germination tests were carried out to study the effect of salinity, temperature regime (night/day) and inoculation with PGPB on germination (percentage and rate), plant height, root length and biomass produced (fresh and dry matter). In the first test, all four ecotypes were considered, whereas in the second test only the CP ecotype was involved because it was found to be the outstanding ecotype in the previous test. Results showed inhibition of germination when salinity was higher in all ecotypes except CP. The CP ecotype showed a decrease of seed germination with an increase in NaCl concentrations at all temperatures tested. However, when it was inoculated with both PGPB, the germination percentage was influenced.