棉铃发育过程中不同组织IAA含量变化特点

为了解IAA与棉纤维品质形成间的关系及棉铃各部位IAA积累转运特点,本研究分析了棉铃各部分在发育过程中IAA含量的变化特点。通过选择陆地棉标准系TM-1、长纤维种质‘母35’和短纤维种质‘208’3个纤维长度差异较大的陆地棉材料,利用酶联免疫法对浙江杭州、海南三亚两地田间试验的各材料不同发育阶段的棉仁、棉籽壳、棉纤维、棉铃壳进行了IAA含量的测定。结果表明,不同参试材料的棉仁IAA含量存在明显差异,棉籽壳、棉纤维与棉铃壳的IAA含量峰值出现时间晚于棉仁,棉铃各个组织IAA含量具有随棉铃组织从内向外逐渐降低的趋势。研究表明,IAA可能是棉纤维发育的正效应因子,且棉铃发育过程中IAA可能呈初期在棉仁富集、随发育进程沿棉铃组织由内向外运输的规律。     

猕猴桃叶片叶绿素含量高光谱估算模型研究

【目的】研究猕猴桃叶片叶绿素含量的高光谱估算方法,为猕猴桃长势的遥感监测提供理论依据。【方法】以陕西杨凌蒋家寨村2018年不同生育期(初花期、幼果期、膨果期、壮果期、果实成熟期)的猕猴桃叶片为研究对象,分别测定其高光谱反射率和叶绿素含量(SPAD值),分析原始光谱和5个常见的植被指数(归一化植被指数、归一化叶绿素指数、改进的叶绿素吸收反射率指数、MERIS地面叶绿素指数、土壤调整指数)与叶绿素含量之间的相关关系,提取各生育期的特征波段,分别建立基于特征波段和植被指数的单波段叶绿素含量一元线性估算模型。利用主成分分析对原始光谱数据进行降维,将得到的主成分得分作为随机森林模型的输入变量,建立基于多波段信息的叶绿素含量多元估算模型,并对模型进行精度验证和分析。【结果】不同生育期猕猴桃叶片光谱反射率变化趋势基本一致,整体趋势为可见光波段反射率低,近红外波段反射率高;在可见光波段,光谱反射率随着叶绿素含量的升高而降低;在近红外波段,光谱反射率则随着叶绿素含量的增加而升高。通过相关性分析可知,初花期、幼果期、膨果期、壮果期、果实成熟期原始光谱的特征波段分别为729,548,707,707和712 nm,估算模型决定系数(R~2)分别为0.18,0.85,0.54,0.85和0.82,其中初花期估算模型未通过显著性检验,其余生育期均通过极显著性检验。在5个常用植被指数中,初花期与叶绿素含量相关性最高的是归一化叶绿素指数(NPCI),但是估算模型决定系数R~2只有0.1,未通过显著性检验;其他生育期与叶绿素含量相关性最高的是MERIS地面叶绿素指数(MTCI),所建立的估算模型拟合效果好,预测精度高。基于主成分分析和随机森林回归建立的不同生育期猕猴桃叶片叶绿素含量估算模型的R~2在0.91～0.98,均通过极显著性检验,其拟合效果和预测精度远高于单波段一元线性回归和基于植被指数的一元线性回归模型,是估算猕猴桃叶片叶绿素含量的最优模型。【结论】基于主成分分析的随机森林模型包含了更完整的波段信息,对不同生育期猕猴桃叶片叶绿素含量具有较好的预测能力。     

秸秆生物炭配施沼液对土壤有机质和全氮含量的影响

为增加沼液中养分在土壤中的滞留量,提高沼液利用效率,本文采用室内土柱试验,研究了不同生物炭混掺量(CK、0.5%、1.0%、2.0%)、生物炭混掺厚度(0、5、10、15、20 cm)和土壤容重(1.30、1.35 g·m^-3)对土壤有机质和全氮含量的影响。结果表明:土壤容重相同时,土柱入渗液渗出速率随生物炭混掺量和混掺厚度的增加而增大;土壤容重不同时,1.35 g·cm^-3土壤土柱入渗液渗出速率小于1.30 g·cm^-3土壤,土壤有机质和全氮含量均呈1.30 g·cm^-3土壤容重小于1.35 g·cm^-3土壤容重;土柱内有机质和全氮含量随生物炭混掺量增大而逐渐增加,生物炭混掺量为2.0%时对土壤有机质和全氮含量影响最大;土柱内有机质含量随生物炭混掺厚度增大而逐渐增加,生物炭混掺厚度为20 cm时对土壤有机质含量影响最大,而全氮含量在土壤容重为1.30 g·cm^-3、混掺厚度10 cm时影响最显著,土壤容重为1.35 g·cm^-3、混掺厚度15 cm时效果较为显著。研究表明生物炭配施沼液时土壤有机质和全氮含量受生物炭混掺厚度、混掺量和土壤容重综合作用的影响。     

绿洲膜下滴灌调亏对马铃薯土壤环境及产量的影响

为测定膜下滴灌调亏马铃薯全生育期内不同调亏水平土壤养分、土壤水热动态、生长动态、产量效应和水分利用效率,于2016年在河西荒漠绿洲灌区民乐县益民灌溉试验站开展了马铃薯不同生育阶段水分调亏灌溉的试验研究,结果表明,马铃薯膜下滴灌调亏土壤水热变化均匀且利用率高,有利于马铃薯对土壤养分的充分吸收和利用;土壤养分是土壤肥力的核心,是植物在生长发育过程中不可或缺的重要因素,膜下滴灌调亏栽培能有效减少土壤速效养分的流失,并提高马铃薯对土壤速效养分的利用效率;不同生育阶段马铃薯耗水量受水分调亏程度影响较大,其耗水量随调亏程度增大而显著减少(P0.05),水分调亏处理马铃薯全生育期总耗水量均低于全生育期充分灌水CK处理。块茎形成期轻度水分亏缺马铃薯水分利用效率、灌溉水利用效率、生物量均达到最大,较全生育期充分灌水显著提高29.04%,35.61%。因此,块茎形成期轻度水分亏缺灌溉方式能使马铃薯根区土壤始终保持湿润状态,有效减少渗漏损失和植株间无效蒸发损失,改善土壤水、肥和热量状况,有利于提高作物水分利用效率,且不显著降低马铃薯最终产量。     

不同胡椒粉中胡椒碱的含量比较

采用高效液相色谱法(HPLC)和紫外分光光度法(UV)测定黑胡椒、胡椒根、市售胡椒粉和用不同浸泡液浸泡脱皮的白胡椒粉中的胡椒碱含量。结果表明：黑胡椒粉、2种市售胡椒粉和白胡椒粉中胡椒碱含量不同；果＞根、白胡椒＞黑胡椒、盐水浸泡＞河水浸泡＞醋浸泡、西安胡椒粉＞海南胡椒粉。说明不同的胡椒粉胡椒碱的含量不同，这可以为胡椒的质量控制提供比较有用的参考。     

免耕和稻草还田对稻田土壤肥力和水稻产量的影响

为了明确稻草还田和免耕等保护性耕作措施对土壤肥力和水稻产量的影响,自2008年于广西大学农学院科研基地进行长期定位试验,设置免耕（NT）、免耕+稻草覆盖还田（NT-SMR）、常规耕作+稻草覆盖还田（CT-SMR）、常规耕作（CT）和常规耕作+稻草翻压还田（CT-SR）5个处理,于2018年水稻成熟期测定产量,水稻收获后分层（0~5、5~10和10~20cm）测定土壤肥力。结果表明,稻田不同土层肥力指标均存在显著性差异,总体上表现为0~5、5~10和10~20cm土层的有机碳、全氮、碱解氮、有效磷和速效钾含量依次下降。NT-SMR处理显著提高了0~5cm土层的有机碳、全氮、碱解氮和有效磷含量,但降低了土壤速效钾含量。在5~10和10~20cm土层,稻草还田处理的有机碳、全氮、碱解氮、有效磷和速效钾含量均优于无稻草还田处理。水稻产量与土壤肥力呈显著正相关。2016年CT-SR处理水稻产量在早季分别比NT和CT处理显著提高了8.52%和7.99%,在晚季分别显著提高了12.12%和7.55%;2018年NT-SMR处理的水稻产量在早季分别比NT和CT处理显著提高了17.78%和10.30%,在晚季分别显著提高了13.88%和19.39%。因此,免耕和稻草还田能明显提高稻田耕作层土壤肥力,增加稻谷产量。     

黄河故道区域不同种植模式及秸秆还田方式对土壤的改良效果

由于长期受到流水冲击,黄河故道区域农田以中低产田为主,因此本区域农田质量提升成为黄河中下游平原绿色发展的重要研究课题。在河南濮阳清丰地区秸秆还田方式的基础上,选取黄河故道区域广泛种植的小麦、玉米和花生三大主要农作物,于2009年进行4种种植模式长期定位试验：小麦-玉米、小麦-花生、小麦-玉米-小麦-花生和单季花生,其中小麦和玉米秸秆全部还田,花生秸秆不还田,探究不同种植模式对土壤理化性质和微生物群落结构的影响。结果表明,秸秆还田量越多,土壤有机质含量提高越多,小麦-花生、小麦-玉米-小麦-花生种植模式下土壤有机质含量最高,且其土壤含水量也显著高于其他处理,上层土壤容重有所降低,显著改善了土壤砂质化,提升了土壤的蓄水能力;秸秆还田量较大的种植模式的养分保持能力明显提高,养分含量显著增加;微生物群落结构对不同种植模式响应结果为,花生可以显著提升微生物丰度,微生物群落多样性随种植作物类型的增加而增加。因此,小麦-玉米-小麦-花生种植模式较为适宜濮阳清丰黄河故道区域,有利于土壤改良和区域农业的可持续发展。     

Lipid-rich bovine serum albumin improves the viability and hatching ability of porcine blastocysts produced in vitro

The effects of lipid-rich bovine serum albumin (LR-BSA) on the development of porcine blastocysts produced in vitro were examined. Addition of 0.5 to 5 mg/ml LR-BSA to porcine blastocyst medium (PBM) from Day 5 (Day 0 = in vitro fertilization) significantly increased the hatching rates of blastocysts on Day 7 and the total cell numbers in Day-7 blastocysts. When Day-5 blastocysts were cultured with PBM alone, PBM containing LR-BSA, recombinant human serum albumin or fatty acid-free BSA, addition of LR-BSA significantly enhanced hatching rates and the cell number in blastocysts that survived compared with other treatments. The diameter, ATP content and numbers of both inner cell mass and total cells in Day-6 and Day-7 blastocysts cultured with PBM containing LR-BSA were significantly higher than in blastocysts cultured with PBM alone, whereas LR-BSA had no effect on mitochondrial membrane potential. The mRNA levels of enzymes involved in fatty acid metabolism and β-oxidation (ACSL1, ACSL3, CPT1, CPT2 and KAT) in Day-7 blastocysts were significantly upregulated by the addition of LR-BSA. The results indicated that LR-BSA enhanced hatching ability and quality of porcine blastocysts produced in vitro, as determined by ATP content, blastocyst diameter and expression levels of the specific genes, suggesting that the stimulatory effects of LR-BSA arise from lipids bound to albumin.     

Organic farming fosters agroecosystem functioning in Argentinian temperate soils: Evidence from litter decomposition and soil fauna

Benefits of organic farming on soil fauna have been widely observed and this has led to consider organic farming as a potential approach to reduce the environmental impact of conventional agriculture. However, there is still little evidence from field conditions about direct benefits of organic agriculture on soil ecosystem functioning. Hence, the aims of this study were to compare the effect of organic farming versus conventional farming on litter decomposition and to study how this process is affected by soil meso- and macrofauna abundances. Systems studied were: (1) organic farming with conventional tillage (ORG), (2) conventional farming with conventional tillage (CT), (3) conventional farming under no-tillage (NT), and (4) natural grassland as control system (GR). Decomposition was determined under field conditions by measuring weight loss in litterbags. Soil meso- and macrofauna contribution on decomposition was evaluated both by different mesh sizes and by assessing their abundances in the soil. Litter decomposition was always significantly higher after 9 and 12 months in ORG than in CT and NT (from 2 to 5 times in average), regardless decomposer community composition and litter type. Besides, mesofauna, macrofauna and earthworm abundances were significantly higher in ORG than in NT and CT (from 1.6 to 3.8, 1.7 to 2.3 and 16 to 25 times in average, respectively for each group). These results are especially relevant firstly because the positive effect of ORG in a key soil process has been proved under field conditions, being the first direct evidence that organic farming enhances the decomposition process. And secondly because the extensive organic system analyzed here did not include several practices which have been recognized as particularly positive for soil biota (e.g. manure use, low tillage intensity and high crop diversity). So, this research suggests that even when those practices are not applied, the non-use of agrochemicals is enough to produce positive changes in soil fauna and so in decomposition dynamics. Therefore, the adoption of organic system in an extensive way can also be suggested to farmers in order to improve ecosystem functioning and consequently to achieve better soil conditions for crop production.     

Impact of soil engineering by two contrasting species of earthworms on their dispersal rates

By burrowing galleries and producing casts, earthworms are constantly changing the structure and properties of the soils in which they are living. These changes modify the costs and benefits for earthworms to stay in the environment they modify. In this paper, we measured experimentally how dispersal behaviour of endogeic and anecic earthworms responds to the cumulative changes they made in soil characteristics. The influence of earthworm activities on dispersal was studied in standardised mesocosms by comparing the influence of soils modified or not modified by earthworm activities on earthworm dispersal rates.The cumulative use of the soil by the earthworms strongly modified soil physical properties. The height of the soil decreased over time and the amount of aggregates smaller than 2 mm decreased in contrast to aggregates larger than 5 mm that increased. We found that: (i) earthworm activities significantly modified soil physical properties (such as bulk density, soil strength and soil aggregation) and decreased significantly the dispersal rates of the endogeic species, whatever the species that modified the soil; (ii) the decreasing in the dispersal proportion of the endogeic species suggests that the cost of engineering activities may be higher than the one of dispersal; (iii) the dispersal of the anecic species appeared to be not influenced by its own activities (intra-specific influences) or by the activities of the endogeic species (inter-specific influences). Overall these results suggest that the endogeic species is involved in a process of niche construction, which evolved jointly with its dispersal strategy.