种植绿肥与稻秸协同还田对单季稻田土壤有机碳库和酶活性的影响

种植绿肥和秸秆还田是稻田土壤培肥的重要措施。研究江汉平原单季稻田冬闲期种植绿肥及稻秸不同利用模式对土壤有机碳库和土壤酶活性的影响,为合理利用秸秆和土地资源提供科学依据。该研究基于3 a田间定位试验,以稻秸不还田不种绿肥(CK1)和不施肥空白(CK0)为对照,分析了冬闲期稻秸全量覆盖单独还田(RSM)、稻秸原位焚烧还田(RSB)、单种绿肥(GM)以及稻秸全量覆盖与种植绿肥协同还田利用(RSM+GM)等处理模式下土壤有机碳各组分含量、碳库管理指数、酶活性的变化及其与水稻产量的关系。结果表明:与CK1和CK0相比,RSB处理3 a后显著降低了土壤稳态有机碳含量,对土壤总有机碳、活性有机碳含量以及碳库管理指数均无显著影响;而GM、RSM及RSM+GM处理3a后显著提高了土壤活性有机碳含量、碳库指数、碳库活度、碳库活度指数和碳库管理指数,尤其是RSM和RSM+GM处理还可显著提高土壤总有机碳含量,且多数指标均以RSM+GM处理增幅为最大,其次是RSM处理。与CK1相比,RSB处理3a后显著提高了过氧化氢酶和蔗糖酶活性,但对土壤脲酶活性无显著影响;而RSM、GM及RSM+GM处理模式3 a后均可显著增加土壤过氧化氢酶、脲酶和蔗糖酶活性,其中RSM+GM处理模式在1 a后即可显著提高土壤脲酶活性,2 a后显著提高土壤过氧化氢酶和蔗糖酶活性,3 a后土壤过氧化氢酶和蔗糖酶活性增幅均是最大。相比于CK1,RSM和RSB处理模式3 a的稻谷增产效果均不显著,而GM和RSM+GM处理模式连续3 a显著提高了稻谷产量,增幅分别为6.88%～11.67%和6.00%～13.40%。相关性分析表明,土壤总有机碳、活性有机碳、碳库管理指数、土壤酶活性与水稻产量之间均呈极显著正相关关系。综上,在江汉平原单季稻作条件下,冬闲期稻秸全量覆盖还田或种植绿肥均可改善土壤肥力,增加作物产量,但前者更有助于土壤有机碳积累,后者更利于作物产量提升。为了兼顾秸秆资源利用、土壤质量改善和作物增产稳产,稻田冬闲期稻秸全量覆盖与种植绿肥协同还田利用模式是一种较好的选择。     

填闲作物腐解过程及其对后茬冬小麦产量的影响

研究了渭北旱塬地区不同填闲作物（长武怀豆（S）、黑麦草（R）及两者1∶1混合（M））翻压和氮肥水平（0、60、120 kg N·hm^-2）双因素处理下，填闲作物的腐解规律、碳氮释放动态及对后茬冬小麦产量的影响，并对腐解速率与Olsen模型进行了拟合。结果表明：各填闲作物翻压后腐解规律及碳氮释放特征均表现为“前期快-中期慢-后期加快”，填闲作物腐解规律符合Olsen模型，在第276天各处理累积腐解率均达70%以上。在第0~35天，同一施氮处理下，累积腐解率和腐解速率均表现为S>M>R（P<0.05）；第35天，S、M和R各处理干物质累积腐解率分别达到61.9%、55.5%和47.5%；在0~35 d，施氮对S、M的腐解影响不显著，对R影响显著，35 d后氮肥效应逐渐减弱；填闲作物的腐解同时伴随其碳、氮的快速释放，在第21天，S、M和R碳氮残留率分别达到40%、50%和60%左右。平均来看，S的碳氮释放速率显著高于R，与M无显著差异。与裸地对照相比，翻压填闲作物能够显著提高后茬冬小麦产量，其籽粒产量增加10%~35% （P<0.05），其中翻压长武怀豆低氮处理和混合翻压低氮处理效果最佳。     

Dough rheological properties and noodle-making performance of non-waxy and waxy whole-wheat flour blends

Dough rheological properties and noodle-making performance of non-waxy whole-wheat flour (WWF) with partial- or full-waxy (PW- or FW-) WWF substitution were studied. The substitution levels were 0, 250, 500, 750, and 1000 g/kg, respectively. FW-WWF reduced the peak viscosity and pasting temperature of WWF blends as its substitution level was increased due to its higher proportions of B-type starch granules and short amylopectin chains, while PW-WWF increased peak viscosity with the increasing substitution level because of its higher amylopectin content. As demonstrated by farinograph and rheometer measurements, FW-WWF interfered with gluten development because of the increased competition for water by arabinoxylans and amylopectin; however, PW-WWF enhanced dough strength due primarily to its increased protein content. Consequently, FW-WWF showed a detrimental effect on cooked noodle texture as the cooked noodle hardness was reduced by 50% at the 1000 g/kg substitution level. In contrast, PW-WWF enhanced noodle integrity and elasticity by increasing cooked noodle cohesiveness and resilience by 10.1% and 14.8%, respectively, at the 1000 g/kg substitution level. The results suggest that with waxy WWF substitution, the changes in starch composition, arabinoxylans, and protein content could modify the interactions among flour components and influence the quality characteristics of noodle products.     

Effects of Dietary Lipids on the Growth Performance,Survival, and Digestive Enzymes of Juvenile Cuttlefish,Sepia lycidas

This study was conducted to determine the effects of dietary lipids on the growth performance, muscle composition, and enzyme activities of the stomach, intestines, and liver of Sepia lycidas juveniles. Fish oil and soybean lecithin were selected as lipid sources to formulate six experimental diets containing lipid levels of 3.68, 4.15, 6.62, 8.09, 9.56, and 11.03%. The feed efficiency first declined and then rose, with the lowest value obtained in individuals fed the 8.09% lipid content diet; the protein efficiency ratio significantly decreased with an increased lipid level. The highest crude protein content and lowest crude lipid content were simultaneously obtained in individuals fed the 9.56% lipid content diet. The activities of pepsase, trypsin, and intestine lipase initially increased before decreasing. The highest activities of protease, trypsin, and lipase were obtained in individuals fed the 9.56% lipid content diet, while the highest activity of amylase was obtained in individuals fed the 6.62% lipid content diet. Hepatic glutamate pyruvate transaminase and glutamic oxaloacetic transaminase initially increased and then held steady, with the highest activities simultaneously obtained in individuals fed the 9.56% lipid diet. Our results suggest that dietary lipids at a level of 9.56% could be the optimal lipid requirement for S. lycidas to grow and maintain normal metabolism.     

岩溶湿地和稻田的土壤酶活性与CO2和CH4排放特征

【目的】探究土地利用变化对湿地土壤酶活性和温室气体排放之间关系的影响。【方法】以会仙岩溶湿地为研究样点,以湖泊湿地和其相邻的稻田为研究对象,采用比色法和静态暗箱法分别测定水稻整个生育期内主要土壤酶的活性及CO₂和CH₄的排放,并对二者之间的关系进行分析。【结果】稻田土壤的β-葡萄糖苷酶、纤维素酶、蔗糖酶、几丁质酶、脲酶和碱性磷酸酶活性均高于湖泊湿地,高出幅度为11.8%—32.7%。稻田CO₂和CH₄排放通量分别为255.9—789.7和-0.41—1.74 mg·m^-2·h^-1,平均值分别为445.8和0.42 mg·m^-2·h^-1,低于天然湖泊湿地。与湖泊湿地相比,稻田CO₂和CH₄排放总量分别降低了22.3%和83.3%,而增温潜势（GHGs,含N₂O）降低了29.6%。相关性结果显示,CO₂排放通量与β-葡萄糖苷酶、纤维素酶、蔗糖酶和几丁质酶活性呈显著负相关关系,CH₄排放通量与6种土壤酶活性显著负相关（P<0.05）。【结论】在会仙岩溶湿地系统中,天然的湖泊湿地转变为稻田可显著提高土壤酶活性,同时降低CO₂和CH₄的排放量,有利于微生物碳利用率的提高和土壤碳的封存。     

昆虫嗅觉相关蛋白的研究进展

昆虫对自然环境中复杂化学信号的识别多依赖于其灵敏的嗅觉系统,选择寄主、觅食、寻找配偶等行为的发生都以嗅觉识别为基础,而完成嗅觉识别还需要多种嗅觉相关蛋白的参与。嗅觉相关蛋白主要包括6种,即气味结合蛋白、化学感受蛋白、气味受体、感觉神经元膜蛋白、离子型受体和气味降解酶。不同种类和性别的昆虫中,嗅觉蛋白的种类、数量和分布各不相同。由于嗅觉蛋白在昆虫识别外界气味分子中的重要作用,国内外近年来对其展开了广泛、深入的研究。本文从几种嗅觉相关蛋白的生化特性、分子结构、生理功能、分布表达部位和研究概况等角度,较详细地综述了近年来国内外昆虫嗅觉相关蛋白的研究进展。     

Supplementing white maize masa with anthocyanins: Effects on masa rheology and on the in vitro digestibility and hardness of tortillas

The aim of this work was to supplement masa made from nixtamalized white maize flour (NWMF) with anthocyanins (0.0, 0.03, 0.06 and 0.12 g/100 g of masa), and to evaluate the effects on the rheological properties of the masa and on color, staling, in vitro digestibility, and hardness of tortillas. Tortilla baking reduced the content of anthocyanins by about 10%. The color parameters of the tortillas added with anthocyanins was similar to that of tortillas made with blue maize. Attenuated total reflection ATR-FTIR spectra showed that the 1022/1047 peak ratio increased, indicative that retrogradation increased with storage time, but the ratio was significantly lower for tortillas with added anthocyanins than without them, and lower for higher anthocyanins concentration. Freshly made tortillas added with anthocyanins exhibited lower ready digestible (about 35%) and slowly digestible (about 20%), but higher resistant (about 45%) starch fractions. Tortillas with 0.12 g of anthocyanins showed significantly lower hardness than the control tortillas (without added anthocyanins). Both previous mentioned effects can be associated with retrogradation, which on turn could be linked to anthocyanins-starch complexes and inhibition of amylolytic enzymes.     

云南马龙县山地封育草地凋落物分解与氮释放的研究

以云南马龙县退化山地草地为研究对象,对封育2年草地的凋落物、土壤水分、凋落物含水率,以及氮素释放进行了研究.结果表明.围栏封育草地凋落物分解速率显著高于未封育草地凋落物分解速率(P<0.05),封育区凋落物增加.起到了一定的保温作用,即可以加速凋落物的分解.同时也减少冬季低温对山地草地的伤害;草地凋落物的干物质分解速率与土壤含水率、凋落物含水率呈显著正相关(r=0.949,P<0.05),封育增加了土壤的含水率,促进了凋落物的分解.总氮的含量与凋落物分解速率成正相关(r=0.995,P<0.05).氨素是调节草地凋落物分解速率的一个重要因素.