优化水肥与滴头间距组合对日光温室黄瓜生长及产量的影响

为探究水肥耦合+滴头间距对宁夏旱区日光温室春夏茬黄瓜生长、产量、品质和水肥利用率的影响。通过3因素3水平正交试验,利用Logistic方程模拟黄瓜株高变化规律,分析了各时期生长特点;利用极差分析和方差分析,研究了水肥耦合+滴头间距影响主次顺序、显著性及变化趋势,同时结合模糊数学隶属函数法对产量和品质指标进行综合评价,筛选最优组合。结果表明:①不同处理下黄瓜株高“S”形生长过程可分为渐增期、速生期、缓增期3个阶段,可用Logistic方程拟合,且相关系数均高达0.97;②春夏茬日光温室黄瓜在采摘期前3个月产量稳定,分别占总产30.19%、29.22%、28.58%,后1个月急剧下降,占总产12%;③3因素影响产量的顺序为灌水量>施肥浓度>滴头间距,灌水量影响显著,施肥浓度和滴头间距影响不显著,产量最高处理为TR1,达144361 kg/hm²,比最低处理TR9高44.92%。采用模糊隶属函数进行综合评价,TR2表现最好,平均隶属函数值为0.70。确定因素最优水平组合为:灌水量3040.95 m³/hm²、施肥浓度200倍液(740.55 kg/hm²)、滴头间距20 cm,产量为141077.9 kg/hm²。     

10％乙霉威·腐霉利微粉剂在设施黄瓜上的沉积分布及残留消解动态

为探究10%乙霉威·腐霉利微粉剂(有效成分质量分数:5%乙霉威,5%腐霉利)在设施黄瓜上施用后的沉积分布特性及残留消解动态,采用PC-3A(S)型激光粉尘仪及粉尘取样片,分别研究了不同设施类型、不同温湿度及不同施药角度下,10%乙霉威·腐霉利微粉剂在设施黄瓜上的沉积分布情况;并于2017年和2018年,分别在北京市进行了该药剂在设施黄瓜叶片和果实中的残留及消解动态试验。结果表明:不同设施类型、不同温度条件下,10%乙霉威·腐霉利微粉剂的沉积分布特性无明显差异,且其有效成分分解率不受温度影响;不同湿度条件下,该微粉剂在黄瓜叶片上的沉积量不同,湿度越大沉积量越多。乙霉威和腐霉利在黄瓜叶片和果实中的消解动态均符合准一级动力学或一级动力学方程,2种药剂在叶片中的半衰期分别为3.2 d和3.0~3.2 d,在果实中的半衰期分别为4.0~4.3 d和3.1~3.8 d。采用10%乙霉威·腐霉利微粉剂,分别按100 g/hm2和150 g/hm2(1.5倍)剂量于黄瓜幼果期施药,最多施药3次,施药间隔期为7 d,距最后一次施药间隔7、10和14 d分别采样,乙霉威在黄瓜果实中的最大残留量为0.88 mg/kg,低于中国国家标准规定的其最大残留限量(MRL)值(5 mg/kg),腐霉利在黄瓜果实中的最大残留量为0.49 mg/kg,也低于其MRL值(2 mg/kg)。该研究结果可为10%乙霉威·腐霉利微粉剂在设施黄瓜上的安全使用提供数据支持。     

水稻稀播条件下不同秧龄壮秧技术

以南粳9108为试验材料,研究稀播条件下(18000苗/m₂)不同措施对30、35 d秧龄秧苗素质的影响。结果表明:在18000苗/m₂的播种密度下,多效唑浸种能够有效地促进根系生长,矮化秧苗高度,显著提高秧苗素质,对于培育不同秧龄的壮苗均有促进作用。多效唑浸种浓度在0.5 g/L左右最为适宜。     

高粱绿肥种植密度对设施黄瓜根系生长相关因子的影响

以设施黄瓜为研究对象,在黄瓜定植前40 d分别播撒240、120、60 kg/hm~2不同密度高粱种子,并于黄瓜定植前将高粱植株作为绿肥翻入土壤,研究其对黄瓜结果期生长指标、根际土壤养分含量以及细菌群落结构变化的影响,探讨其影响黄瓜生长指标、根际养分含量和菌群结构变化的内在机制。试验结果表明:240 kg/hm~2种植密度的高梁绿肥可显著提高黄瓜根际土壤有机质质量比31.66%、碱解氮质量比8.75%、速效磷质量比13.89%、速效钾质量比16.86%、脲酶活性6.85%,显著提高结果期黄瓜茎粗12.83%、根系数15.81%、根总体积24.11%、叶片总面积11.43%、单株结瓜数10.97%、总产量9.81%;240 kg/hm~2种植密度的高粱绿肥可明显提高黄瓜根际土壤中变形菌门、放线菌门、厚壁菌门比例而降低酸杆菌门、绿弯菌门、拟杆菌门比例,明显提高鞘脂单胞菌科、黄色单胞菌科、红螺菌科、中华杆菌科、生丝微菌科比例而降低Gp6科、Gp16科、Gp4科比例。该处理主要通过降低根际土壤绿弯菌门和提高鞘脂单胞菌科、中华杆菌科比例而提高脲酶活性,通过提高厚壁菌门、黄色单胞菌科、红螺菌科和降低根际土壤酸杆菌门比例而促进碱解氮质量比、速效磷质量比、茎粗、叶片总面积、根系数、根总体积的提高,最终促进黄瓜生长并提高产量。     

Changes in soil and water quality at sediment–water interface of Penaeus vannamei culture pond at varying salinities

The health of the pond environment in shrimp farming is important for sustainable and profitable aquaculture, in which sediment–water interface is the most important influencing area. With this objective, the key parameters of water and sediment at the interface was studied in shrimp ponds with varying salinities and compared with the surface water and soil to understand the variations and the underlying causes. Total ammonia nitrogen and total alkalinity were higher in water at the interface as compared to surface water, whereas pH, nitrite, oxide forms of nitrogen (NO₃), phosphorus (PO₄) and oxidizing bacteria were observed to be lower. There was no significant difference with respect to macrominerals such as sodium, potassium, calcium and magnesium between water at the interface and surface. These changes are profoundly influenced by the uppermost 1.0‐cm thick sediment layer, where the maximum transition of nutrients takes place with the water column. The outcome of the study highlights the effectiveness of water sampling for metabolites at the interface, which reflects at an early stage any potential deterioration of pond environment, which will help the farmer to initiate timely mitigation measures.     

Cucumis metuliferus is resistant to root‐knot nematode Mi1.2 gene (a)virulent isolates and a promising melon rootstock

Pot experiments were carried out to characterize the response of two Cucumis metuliferus accessions (BGV11135 and BGV10762) against Mi1.2 gene (a)virulent Meloidogyne arenaria, M. incognita and M. javanica isolates and to determine the compatibility and the effect on physicochemical properties of fruit melons. In addition, histopathological studies were conducted. One week after transplanting, plants were inoculated with one J2 cm^?3 of sterilized sand (200 cm³ pots) and maintained in a growth chamber at 25 °C for 40 days. The susceptible cucumber cv. Dasher II or melon cv. Paloma were included for comparison. The number of egg masses and number of eggs per plant were assessed, and the reproduction index (RI) was calculated as the percentage of eggs produced on the C. metuliferus accessions compared to those produced on the susceptible cultivars. The compatibility and fruit quality were assessed by grafting three scions, two of Charentais type and one of type piel de sapo, under commercial greenhouse conditions. The resistance level of both C. metuliferus accessions ranged from highly resistant (RI < 1%) to resistant (1% ≤ RI ≤ 10%) irrespective of Meloidogyne isolates. Melon plants grafted onto C. metuliferus accession BGV11135 grew as self‐grafted plants without negatively impacting fruit quality traits. Giant cells induced by Meloidogyne spp. on C. metuliferus were in general poorly developed compared to those on cucumber. Furthermore, necrotic areas surrounding the nematode were observed. Cucumis metuliferus accession BGV11135 could be a promising melon rootstock to manage Meloidogyne spp., irrespective of their Mi1.2 (a)virulence, without melon fruit quality reduction.     

海参捕捞装置导航中低成本陀螺仪的降噪研究与试验

针对MEMS陀螺仪输出信号中含有的随机漂移噪声造成海参捕捞装置惯性导航精度明显下降的问题,采用时间序列分析法和Kalman滤波算法,对MEMS陀螺仪随机漂移噪声的削减问题进行研究。以MEMS惯性测量单元的实测数据和三维电子罗盘测量的姿态角为样本,对本研究的低成本陀螺仪的降噪效果进行测试,试验结果表明:1)经过降噪处理后的陀螺仪随机漂移信号的方差比陀螺仪原始采样信号的方差降低1个数量级,显著改善了陀螺仪随机漂移数据的精密度;2)以高精度三维电子罗盘实测的姿态角作为参考基准,将降噪后的陀螺仪随机漂移数据导入捷联惯导姿态更新算法程序,在300s时间内,解算出的俯仰角、横滚角和航向角的均方根误差RMSE全部小于1°;与降噪前相比,相应的俯仰角、横滚角、航向角的RMSE分别降低了170.5、97.6和42.5倍,明显提高了惯性导航精度。     

根施5-氨基乙酰丙酸对亚适宜温光下黄瓜幼苗生长的影响

为缓解亚适宜温光环境对黄瓜幼苗生长产生的不利影响,以中农26号为试验材料,研究亚适宜温光下根施不同浓度5-氨基乙酰丙酸(ALA)对黄瓜幼苗生长和生理特性的影响。结果表明,亚适宜温光下,根施5 mg·L^-1 ALA可以显著提高黄瓜幼苗的全株干重、壮苗指数和根系活力,与对照相比,黄瓜幼苗全株干重和壮苗指数分别提高了32.5%和47.1%,根系活力提高了95.0%。根施5 mg·L^-1 ALA能够显著增加幼苗叶片叶绿素和ALA含量,与对照相比,总叶绿素和ALA的含量分别提高了49.5%和55.7%。根施5 mg·L^-1 ALA黄瓜幼苗的净光合速率(Pn)和气孔导度(Gs)分别较对照提高了22.9%和42.2%。根施5 mg·L^-1ALA后,抗氧化酶活性显著提高,叶片和根系的丙二醛(MDA)含量分别比对照降低了35.3%和18.1%。同时,根施适宜浓度的ALA对矿质元素的吸收和运输产生有一定影响,但对叶绿素合成过程中相关基因的表达无明显调控作用。本研究为缓解黄瓜幼苗亚适宜温光伤害提供了新方法,也为ALA在设施农业上的应用提供了技术支持。     

Optimization of the stocking parameters for mud spiny lobster Panulirus polyphagus (Herbst, 1793) capture‐based aquaculture in tropical open sea floating net cages

Mud spiny lobsters, Panulirus polyphagus (Herbst, 1793), were reared at four different stocking sizes and stocking densities in open sea cages to evaluate their effects on growth performance. To evaluate the effect of stocking size on the growth performance, the lobsters were segregated into four different treatment groups according to size and were stocked at a density of 300 animals per cage. To evaluate the effect of stocking density on the growth performance, lobsters of 81–100 g were stocked in four different stocking densities, i.e. 16/m², 24/m², 32/m² and 40/m². The results showed that the growth rate of (60–80 g) size group, was significantly higher compared to the size groups, i.e. 101–120 g and 121–140 g comprising of larger individuals. The final body weight, though significantly higher in 81–100 g as compared to 60–80 g, the growth performance (i.e. weight gain percentage (WG %) and specific growth rate (SGR)) were not significantly different. The density‐dependent influence on growth performance was evident in this study. The WG % and SGR during 90 days’ culture period was significantly higher in 24/m² compared to other groups. This study provides crucial information about the appropriate stocking density and stocking size of lobsters at the field level, which would help to promote sustainable lobster cage farming by maximizing the production potential of the system.     

Effects of natural feeding stimulants and glutamic acid supplementation on the feed intake,growth performance and digestive enzyme activities of red sea bream (Pagrus major) fed fish meal‐free soy protein concentrate (SPC)‐based diet

Two experiments were conducted for red sea bream (Pagrus major). In experiment 1, the optimum level of glutamic acid and natural feeding stimulants to enhance feed intake were determined and found that glutamic acid level of 0.5% and fish meat hydrolysate (FMH) were effective. In experiment 2, fish were fed with soy protein concentrate (SPC)‐based diet with synthetic feeding stimulants (Basal diet), the Basal diet with FMH (FMH diet), the FMH diet with glutamic acid (FMHG diet) and with fish meal diet (FM diet) as a control until satiation for 8 weeks. Feed intake of FMHG‐fed fish was significantly higher than others (p < 0.05). Specific growth rate and the feed conversion ratio of FMHG were comparable to those of FM‐fed fish (p > 0.05). Relative visceral fat ratio and crude lipid content of any SPC‐based diet‐fed fish tended to be lower than those of FM diet‐fed fish. There were no significant differences in trypsin and lipase activities hepatopancreas among treatments. SPC can be utilized as a sole protein source in a diet for red sea bream. The lower growth performance in SPC‐based diet‐ fed fish was not due to poor digestive enzyme secretion but could be associated with lipid utilization disorder.