坡缕石种薯包衣剂对马铃薯产量及品质的影响

采用单因素随机区组设计研究了纯坡缕石包衣和复合坡缕石包衣对马铃薯生长及品质的影响.结果表明:坡缕石包衣可显著提高马铃薯出苗率,复合坡缕石包衣处理效果优于纯坡缕石包衣处理;坡缕石包衣可促进植株生长,纯坡缕石包衣处理的株高大于复合坡缕石包衣处理;此外,坡缕石包衣处理还有助于提高马铃薯产量和商品率,提高马铃薯的干物质和淀粉含量,降低还原糖含量.     

大黄鱼冷诱导结合蛋白(CIRP)基因cDNA克隆及低温胁迫对其时空表达的影响

为研究冷诱导结合蛋白(CIRP)在大黄鱼低温适应过程中的作用,采用同源克隆技术获得了大黄鱼CIRP基因,并通过实时荧光定量PCR(qRT-PCR)技术检测了低温胁迫下大黄鱼各组织中CIRP基因的表达变化。结果显示,大黄鱼CIRP基因cDNA序列全长1211 bp,推测编码一个由182个氨基酸组成、分子量为19 ku的蛋白。序列比对显示硬骨鱼类CIRP基因序列较为保守,特别是N端的RNA识别基序(RRM)高度保守。系统进化树分析显示大黄鱼CIRP与银鳕相似性最高(81.5%),所有硬骨鱼类聚为一个大支。慢性低温胁迫中(12℃缓降至6℃),皮肤和肌肉中CIRP基因的表达量呈随温度降低而升高的趋势,6℃时表达量分别为12℃时的11.56倍和9.03倍;鳃、脑和心脏中CIRP基因表达量均呈先显著上升后显著下降的趋势,其峰值均出现在8℃时,表达量分别为12℃时的5.07、7.69和2.83倍;肠、肾脏、肝脏和脾脏中的表达量随温度降低而下降,6℃时的表达量最低,与12℃时相比降幅分别为80.0%、65.6%、91.2%、55.6%。急性低温胁迫(由12℃骤降至8℃并胁迫4 h)条件下,鳃、皮肤、脑、肝脏、心脏中CIRP基因表达量均呈先升高后降低的变化,反映了机体对低温胁迫的应激、适应过程;肌肉和肠中的表达量则始终显著低于胁迫前。慢性和急性低温胁迫中各组织CIRP表达量变化的差异提示,大黄鱼机体在低温胁迫响应和适应中有着多种调节机制。研究表明,CIRP基因参与了大黄鱼应对低温胁迫的过程。     

不同灌溉方法对不同氮肥在温室土壤-植株中的氮素分配影响

以番茄为供试作物,采用田间微区试验的方法研究了不同灌溉方法和不同氮肥种类对氮素在土壤不同层次间的残留以及在番茄植株不同部位之间的分配。结果表明,在番茄整个生育期内,土壤中无机氮主要以NO3--N的形式存在,NH4+-N所占比例很小。0～100cm土层中,滴灌和沟灌各处理土壤中NH4+-N的含量在整个生育期内含量均比较低(低于6mgkg-1),且变化幅度不大,各土层NH4+-N的含量受灌溉方式和施肥的影响较小。无论是滴灌还是沟灌,番茄全生育期内0～20cm土层土壤NO3--N含量始终较高。沟灌易引起土壤中NO3--N向下层迁移,而滴灌对40～60cm土层及其以下各层次土壤的NO3--N分布影响作用不明显。硝态氮肥较铵态氮肥和酰胺态氮肥更易随水向深层土壤迁移。灌溉方式对肥料15N在果实、茎、叶中的分配比例没有明显影响,肥料15N在番茄地上部分各器官所含的量以果实为最高,其次为叶,茎中的含量最少;两种灌溉方法间肥料15N在果实、茎、叶的分配比例差异不大,平均为2.9∶1∶1.6。     

Extraction and Characterization of Phospholipid-Enriched Oils from Antarctic Krill (Euphausia Superba) with Different Solvents

Krill oils (KOs) were extracted from Antarctic krill using ethanol, hexane, or their mixture (1:2, v/v) with yields of 21.32%, 8.50%, and 18.75%, respectively. The total nitrogen content of the aforementioned oils was 2.76%, 1.06%, and 1.87%, respectively, indicating the presence of lipoprotein. All KOs contained a high proportion of phospholipid (PL) (30.20–64.82% of total lipids) and polyunsaturated fatty acids (PUFA) (30.00–34.94% of total FAs). Among PL, phosphatidylcholine was dominant (89.81–90.60 mol %). In contrast, KO extracted with the mixed solvent had the highest amount of glycerophosphocholine species containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).     

Effects of supplemental phytic acid on the apparent digestibility and utilization of dietary amino acids and minerals in juvenile grass carp (Ctenopharyngodon idellus)

A feeding trial was conducted for 8 weeks to evaluate the effects of supplemental phytic acid (PA) on the apparent digestibility and utilization of dietary amino acids (AAs) and minerals in juvenile grass carp. Five experimental diets consisted of graded levels of PA (0.2, 4.7, 9.5, 19.1 and 38.3 g kg^?1, named as P0, P5, P10, P20 and P40). Triplicate groups of fish (initial weight, 22.37 ± 0.16 g) were fed twice daily (08:00 and 16:00 h). The crude protein content in whole body significantly (p < .05) decreased in fish fed with 19.1 and 38.3 g PA kg^?1 diet. Supplemental PA (>4.7 g kg^?1) significantly reduced the apparent digestibility coefficient (ADC) of AAs (Asp, Thr, Ser, Glu, Gly, Ala, Cys, Val, Met, Ile, Leu, Phe, Lys, Pro, His and Arg) and the ADC of minerals (P, Ca, Mg, Zn, Cu, Fe and Mn) in grass carp. The contents of minerals (P, Ca, Mg and Zn) in whole body and bone were also found to be significantly reduced in dietary PA > 4.7 g kg^?1, while the bone ash, serum Alkp and Zn contents were found to be significantly decreased when the PA supplementation level was above 9.5 g kg^?1, and the contents of serum Ca and Mg were found to be markedly altered in higher PA‐supplemented groups. The results indicated that supplemental PA decreased the apparent digestibility and utilization of AAs and minerals, and thus reduced the feed utilization of grass carp, suggesting that the level of total PA should be below 4.7 g kg^?1 in grass carp diet.     

Effects of Neutral Phytase Supplementation on Biochemical Parameters in Grass Carp,Ctenopharyngodon idellus,and Gibel Carp,Carassius auratus gibelio,Fed Different Levels of Monocalcium Phosphate

Two 8‐wk studies were conducted to evaluate the effects of neutral phytase supplementation on hemato‐biochemical status, liver biochemical parameter, and intestinal digestive enzyme activity of grass carp, Ctenopharyngodon idellus, and gibel carp, Carassius auratus gibelio, fed with different levels of monocalcium phosphate (MCP). The control diet was prepared with 2% MCP but without phytase (P2.0). The other three experimental diets were prepared with the addition of 1.5, 1.0, and 0.5% MCP, respectively, when supplemented with 500 U/kg neutral phytase in each diet and designated as PP1.5, PP1.0, and PP0.5, respectively. The results indicated that the serum alkaline phosphatase (ALP), alanine transaminase (ALT), and aspartate transaminase (AST) activities, as well as the albumin (ALB) content were increased in grass carp (P < 0.05) and gibel carp (P > 0.05) fed with phytase‐supplemented diets. Meanwhile, the serum cholesterol, high‐density lipoprotein, and total protein contents of the two species of fish were increased in comparison to the control. In addition, dietary phytase inclusion did not significantly affect hepatic ALP, ALT, and AST activities in the two species of carp fed with different levels of MCP. Amylase activity increased in foregut and hindgut of both species when fed with the phytase‐supplemented diets while lipase activity was reduced in the foregut and hindgut in both fish. This study suggests that neutral phytase supplementation increases serum ALP, ALT, and AST activities but does not notably affect these enzyme activities in the liver of the two species of carp when fed different levels of MCP. On the other hand, amylase activity increased while lipase activity was reduced in the intestine of the species of carp fed with phytase‐supplemented diets.     

密云水库库区不同植物篱模式下的氮磷阻控效应

筛选拦截效果最佳、经济效益最佳的植物篱模式,为密云水库水源保护区控制坡耕地氮磷流失提供技术参考。设置“桔梗+狗牙根”“丹参+狗牙根”“桑树+野牛草”“黄芩+野牛草”4种不同的植物篱模式,监测2020年天然降水条件下的地表径流、泥沙以及养分情况,分析不同植物篱模式下径流小区的产流和产沙情况,探讨不同植物篱对坡耕地地表径流、泥沙和养分的拦截效率及其影响因素。结果表明：4种植物篱种植模式都能够起到截流减沙,减轻水环境富营养化的作用,从而避免对下游水体的污染。其中“桑树+野牛草”植物篱效果最为显著,大雨雨强下可以减流57.96%,减沙96.64%,暴雨雨强下可以减流64.63%,减沙97.17%;对氮的相对拦截量为93.14 mg,相对拦截率约88.27%;对磷的相对拦截量为25.17 mg,相对拦截率约80.72%,能有效减少地表径流中的氮、磷含量。在考虑经济效益、社会效益和生态效益下,开展植物篱防控面源污染工作中,最佳的物种选择为“桑树+野牛草”,其次为“黄芩+野牛草”。野牛草在防控水土流失与面源污染方面效果十分显著,可以作为水土保持的先锋植物推广。     

鄱阳湖地区耕地变化及其驱动力研究Ⅰ.耕地数量及空间变化分析

依据鄱阳湖地区1949～2002年耕地面积和社会经济统计数据,分析耕地面积变化趋势。结果表明,在近53年里,鄱阳湖地区耕地面积经历了快速增长(1949～1957年)、大幅减少(1957～1978年)、缓慢减少(1978～1995年)、波动变化(1995～1999年)和迅速减少(1999～2002年)五个阶段。而在空间变化上,不同县市的变化率相差很大,通过聚类分析将20个县市分为四类。     

Effects of stocking density, diet, and water exchange on growth and survival of pearl oyster Pinctada maxima larvae

Three experiments were carried out to separately investigate the effects of stocking density (1.0, 2.0, 4.0 and 8.0 larvae ml^?1), diet (Isochrysis zhanjiangensis, Chlorella spp., Nannochloropsis oculata, 50 % I. zhanjiangensis/50 % Chlorella spp. and 50 % I. zhanjiangensis/50 % N. oculata), and water exchange (25 % once every other day and 25, 50 and 100 % once daily) on growth and survival of pearl oyster Pinctada maxima larvae. Results showed that there existed significant effects of stocking density, diet, and water exchange on the growth of pearl oyster larvae (P < 0.05). Larval survival was significantly affected by stocking density and diet (P < 0.05), but not by water exchange (P > 0.05). Larval growth decreased significantly with increasing stocking density (P < 0.05). A density of 1.0–4.0 larvae ml^?1 was optimal for larval growth of pearl oyster. Chlorella spp. and N. oculata could replace 50 % of I. zhanjiangensis as a food source for the pearl oyster larvae without affecting growth and survival. A water exchange of 25 % once daily provided optimum larval growth and survival.     

Effects of dietary selenium on growth performance and oxidative stress in juvenile grass carp Ctenopharyngodon idellus

An 8‐week feeding trial was conducted to investigate the effect of dietary selenium (Se) on feed intake, weight gain and antioxidant activity in juvenile grass carp (11.2 ± 0.03 g). Six Se levels (0.13, 0.41, 0.56, 1.12, 2.18 and 4.31 mg/kg) of semi‐purified diets were assayed in triplicate. The maximum weight gain, specific growth rate and feed intake were obtained in fish fed with 1.12 mg Se/kg diet. Hepatic glutathione peroxidase activity was markedly increased when dietary Se ≤1.12 mg/kg diet and reached a plateau when dietary Se ≥1.12 mg/kg diet. Hepatic superoxide dismutase and serum catalase activities in juvenile grass carp fed with 0.56, 1.12 and 2.18 mg Se/kg diets were all significantly higher than those in the other groups. The malondialdehyde content in liver and serum was firstly decreased and then increased with increasing dietary Se content, and the lowest content was observed in fish fed with 1.12 mg Se/kg diet. With the increase in Se level, the activities of serum alanine aminotransferase and aspartate aminotransferase were reduced. In addition, serum alkaline phosphatase activity and albumin content were highest in fish fed with 1.12 mg Se/kg diet. This study indicated that both the Se deficiency and excess of Se caused negative effect on the oxidative stress in juvenile grass carp and suggested that the health‐giving concentration of dietary inorganic Se was 1.12 mg/kg diet. Moreover, based on the broken‐line regression analysis of weight gain, the optimal concentration of dietary inorganic Se was 0.83 mg/kg for juvenile grass carp.