日本对虾越冬亲虾性腺促熟及工厂化育苗技术研究

1997、1998年利用越冬亲虾进行性腺促熟,用镊烫法切除眼柄,促进亲虾发育。结果:两年共培育亲虾雌虾8204尾。雄虾5683尾,获交尾虾5360尾。交尾率为71.81％。每年两批育苗,共利用水体1720m~3,育出0.7～1.1cm的虾苗12450万尾,平均单位水体出苗量为7.24万尾/m~3,效益显著。     

毛蚶在不同底质与撒播方式下潜沙行为的观测与分析

为了探究不同底质与撒播方式对毛蚶(Scapharca subcrenata)潜沙行为的影响,在实验室条件下,观察了壳长(10.0±0.9)mm毛蚶的潜沙过程,并研究了沙质(粒径251~500μm)和泥沙质(粒径120μm)两种底质和播散方式(集中和分散)对毛蚶潜沙时间和潜沙率的影响。结果显示,毛蚶潜沙过程分为准备、潜沙及结束3个阶段。在两种底质条件下,集中播撒方式的毛蚶潜沙时间均短于分散播撒方式,但同种底质不同播撒方式下的毛蚶潜沙时间差异不显著(P0.05)。无论是集中播撒还是分散播撒,沙质条件下毛蚶的潜沙时间均短于泥沙质的潜沙时间,并且在分散播撒方式下,两种底质的差异达到显著水平(P0.05);两种底质条件下,毛蚶的潜沙率均表现为集中播撒高于分散播撒。研究表明,与泥沙质底质相比,毛蚶在沙质条件下更易于快速潜底;与分散播散方式相比,集中播撒更利于毛蚶快速潜底。     

Polygalacturonase and β-galactosidase activities in Hayward kiwifruit as affected by light exposure,maturity stage and storage time

Softening process and total antioxidant activity were evaluated in kiwifruit differently exposed to light intensity and harvested at two different times (October 10 and November 14). Fruit was stored for 2 months at 0 °C (S1) and then maintained for a week at ambient temperature (S2). The results showed that fruit harvested later presented a faster softening rate during storage than fruit harvested earlier, even if antioxidant activity did not change. Light-exposed fruit showed higher flesh firmness than that of shaded ones. Polygalacturonase activity was higher in kiwifruit maintained for a week at ambient temperature after cool storage and, in particular the highest value was recorded in fruit harvested later. The behaviour of β-galactosidase was different: it did not show changes in fruit harvested later and significantly decreased in light- and shade-exposed fruit harvested earlier.     

Tomato yield, biomass accumulation, root distribution and irrigation water use efficiency on a sandy soil, as affected by nitrogen rate and irrigation scheduling

Florida is the largest producer of fresh-market tomatoes in the United States. Production areas are typically intensively managed with high inputs of fertilizer and irrigation. The objectives of this 3-year field study were to evaluate the interaction between N-fertilizer rates and irrigation scheduling on yield, irrigation water use efficiency (iWUE) and root distribution of tomato cultivated in a plastic mulched/drip irrigated production systems. Experimental treatments included three irrigation scheduling regimes and three N-rates (176, 220 and 230 kg ha⁻¹). Irrigation treatments included were: (1) SUR (surface drip irrigation) both irrigation and fertigation line placed right underneath the plastic mulch; (2) SDI (subsurface drip irrigation) where the irrigation line was placed 0.15 m below the fertigation line which was located on top of the bed; and (3) TIME (conventional control) with irrigation and fertigation lines placed as in SUR and irrigation being applied once a day. Except for the “TIME” treatment all irrigation treatments were controlled by soil moisture sensor (SMS)-based irrigation set at 10% volumetric water content which was allotted five irrigation windows daily and bypassed events if the soil water content exceeded the established threshold. Average marketable fruit yields were 28, 56 and 79 Mg ha⁻¹ for years 1-3, respectively. The SUR treatment required 15-51% less irrigation water when compared to TIME treatments, while the reductions in irrigation water use for SDI were 7-29%. Tomato yield was 11-80% higher for the SUR and SDI treatments than TIME where as N-rate did not affect yield. Root concentration was greatest in the vicinity of the irrigation and fertigation drip lines for all irrigation treatments. At the beginning of reproductive phase about 70-75% of the total root length density (RLD) was concentrated in the 0-15 cm soil layer while 15-20% of the roots were found in the 15-30 cm layer. Corresponding RLD distribution values during the reproductive phase were 68% and 22%, respectively. Root distribution in the soil profile thus appears to be mainly driven by development stage, soil moisture and nutrient availability. It is concluded that use of SDI and SMS-based systems consistently increased tomato yields while greatly improving irrigation water use efficiency and thereby reduced both irrigation water use and potential N leaching.     

射流自吸喷灌泵喷嘴系数的理论推导与试验

为了研究射流式自吸喷灌泵射流喷嘴的内特性,利用流体力学基本原理,对射流喷嘴阻力系数、流量系数进行了理论推导.设计了4种不同尺寸的射流喷嘴,对4种喷嘴的阻力系数、流量系数进行了理论计算,得到了不同出口直径下各系数的变化规律.对分别安装4种射流喷嘴的喷灌泵进行了自吸性能的试验.结合试验结果和各系数的变化规律,分析了射流喷嘴阻力系数和流量系数对射流式自吸喷灌泵自吸性能的影响.结果表明,随着喷嘴出口直径的增大,阻力系数减小,流量系数增大,自吸时间缩短,但达到一定程度后,卷吸作用减弱,自吸性能变差.     

滴灌施肥条件下氮钾分配时期对甘蔗产量和品质的影响

滴灌施肥技术是现代可持续农业发展的一项综合管理技术措施.本试验采用露天盆栽进行甘蔗种植,设置了滴灌条件下4个氮钾分配时期,同时设置了一个常规种植方式作对比.研究结果表明,滴灌施肥显著促进了甘蔗的生长,在施用常规氮钾肥用量1/2的情况下,比常规施肥获得更高的甘蔗产量.滴灌条件下,氮钾不同分配时期对甘蔗产量和品质有显著影响.通过滴灌系统按甘蔗"苗期、分蘖期一伸长期一成熟期"以20%一60%一20%的氟钾肥料比例分多次施用的处理效果最好,甘蔗的茎长、产量、甘蔗品质、甘蔗根系等都优于其他的分配方式,其单茎重达1.92 kg,甘蔗蔗糖分含量达到17.26%.通过滴灌系统合理施用氮钾肥既有经济效益,又有环境效益.     

Interactions between fishing strategies of Nephrops trawlers in the Bay of Biscay and Norway lobster diel activity patterns

Abstract  Norway lobster, Nephrops norvegicus (L.), in the Bay of Biscay exhibited diel activity patterns with more individuals outside their burrows at dawn and dusk, increasing catchability at these times. Data from an on board observer programme on Nephrops trawlers between 2002 and 2005 were used to assess variability in catchability in commercial catches. Catch numbers per haul varied spatially and between months, but no signal for diel variations was found. Fishing strategies developed by the Nephrops trawlers had several components. On a seasonal level, they started around sunrise. On a haul level, haul duration decreased from haul to haul, with the longest hauls taking place at the time of the highest catchability. By-catch of hake, Merluccius merluccius (L.), increased more than proportionally with haul duration.     

贵州林火发生时间卫星监测动态分析

根据国家林业局西南卫星林火监测分中心2005~2010年贵州林业卫星监测数据及相关信息的分析,对贵州省林火发生时间进行动态分析,结果表明,2009~2010年持续高温干旱,火灾发生频率较高,1~2月份进入高危火险时间,3~4月进入高峰期。分析结果为有针对性地制定防火规划提供依据。     

高温胁迫下水稻胚乳淀粉分支酶各同工型基因的表达特征

 以稻米品质温度敏感型的早籼稻品种浙辐49为材料,利用人工气候箱控温处理试验和实时荧光定量PCR技术,探讨了水稻发育胚乳中淀粉分支酶(starch branching enzyme, SBE)的3种主要同工型基因 (SBEⅠ、 SBEⅢ和SBEⅣ) 在不同温度处理下的相对表达量差异及动态变化特征。结果表明,高温处理对水稻胚乳中SBE基因的表达调控因其同工型的种类而异,SBEⅣ基因在高温处理下呈上调表达,而SBEⅠ和SBEⅢ基因在高温处理下的相对表达量则明显降低,表现为下调表达;与SBEⅣ等同工型相比,水稻胚乳中SBEⅠ基因对高温胁迫的表达响应相对更敏感。     

吴震东公式简化计算研究

混凝土工程冬季施工主要采用非加热养护方法,这类方法的技术关键是精确的热工计算,而热工计算目前仍广泛应用吴震东理论,按吴震东理论建立的整套公式可以描述混凝土在各咎情况下温度时间变化规律,但由于吴东公式较为复杂,许多学者对简化吴震东公式作了深化入的研究和讨论,据此分析了简化吴震东公式的思路、途径与方法,并评价了各类简化公式和近似公式的优点与不足之处。