基于不同方法的汉中盆地稻麦轮作土壤供氮能力评价

【目的】比较多种指标评价汉中盆地稻麦轮作土壤供氮能力的可靠性,为当地土壤氮素管理提供参考。【方法】以采集于汉中盆地及周边丘陵区的12个农田耕层土壤为供试土样,以盆栽黑麦草地上部累积吸氮量为参比,以土壤理化性质指标以及矿质氮法、KCl冷凝回流法、酸性高锰酸钾法3种化学方法和淹水培养法、通气培养法2种生物培养方法测定土壤氮素矿化量作为土壤供氮能力指标。【结果】土壤类型是影响土壤供氮能力的重要因素;土壤全氮或有机质可以反映土壤潜在供氮能力;土壤质地、pH、有效磷、CEC、碳酸钙、颗粒组成（砂粒、粉粒、黏粒）均不能反映稻麦轮作土壤供氮能力。矿质氮法测定氮素值与作物吸氮量相关系数为 0.963（P<0.01）,但由于起始矿质氮不能反映有机氮矿化量,故矿质氮法只能反映当前供氮能力,不宜作为土壤供氮能力评价指标;KCl冷凝回流法测得的总矿质氮量与作物吸氮量相关系数为0.912（P<0.01）,而KCl冷凝回流法测得的可矿化氮量与作物吸氮量相关系数为-0.766（P<0.01）,由于KCl冷凝回流法浸取土壤可矿化氮过程中会造成铵态氮的挥发,导致在反映土壤潜在供氮能力和总供氮能力上可能不一致,故KCl冷凝回流法不是反映汉中盆地土壤供氮能力的理想指标;酸性高锰酸钾法测得的总矿质氮量和可矿化氮量与作物吸氮量相关系数分别为0.847和0.833（P<0.01）,既能够反映土壤潜在供氮能力,又能够反映总供氮能力,是最佳化学方法。通气培养条件下,总矿质氮量和可矿化氮与作物吸氮量均不相关,而在淹水培养条件下,总矿质氮量和可矿化氮与作物吸氮量的相关系数分别为0.921和0.890（P<0.01）,表明淹水培养法可以反映汉中盆地稻麦轮作土壤潜在供氮能力和总供氮能力,是良好的生物培养方法。氮素矿化势（N₀）和起始矿质氮+N₀与前4期黑麦草地上部累积吸氮量相关系数分别为0.834和0.845（P<0.01）,与整株累积吸氮量相关系数分别为0.840和0.851（P<0.01）。表明,N₀和起始矿质氮+N₀均可反映土壤潜在供氮能力,但N₀仅能够反映土壤潜在供氮能力,起始矿质氮+N₀可反映土壤潜在供氮能力和总供氮能力,因此,起始矿质氮+N₀是评价汉中盆地稻麦轮作土壤供氮能力的理想指标。【结论】对于汉中盆地稻麦轮作土壤供氮能力的评价,酸性高锰酸钾法是最佳化学方法;淹水培养法是良好的生物培养方法,起始矿质氮+N₀是反映汉中盆地土壤供氮能力的理想指标。     

池塘循环流水养殖模式(IPA)应用现状及发展潜力

为了进一步推进中国池塘养殖模式的转型升级,大力发展环境友好型养殖模式,本文归纳了中国淡水鱼养殖业发展现状,总结了近年中国池塘循环流水养殖模式(IPA)的示范应用情况,分析了IPA系统的组成及其优势,指出了该模式在不同养殖品种应用过程中存在的问题及工艺缺陷,提出了优化方案和建议。笔者认为该模式适合规模化经营,可降低管理成本提升养殖效益,在推广应用时应根据养殖品种特性对IPA系统组件和养殖工艺进行调整和再创新,以便于适应不同名特优品种的需求。由于IPA模式具有节水、生态、高效、环保等优势,符合中国水产养殖的未来发展要求,因此,在中国淡水养殖产业中具有广阔的应用前景和发展空间。     

甘肃省天水市畜禽粪肥资源现状及替代化肥潜力研究

综合考虑农作物种植结构、种植面积及畜禽粪污处理方式等因素,估算了天水市各县区粪污养分资源现状及其替代化肥的潜力。结果表明,天水市畜禽粪污中氮、磷养分分别为22 565.01t和3 384.75t,且各县区畜禽粪污氮和磷供给量均未超过作物需求量;当前天水市大部分养殖场固体粪污储藏堆放还田,液体粪污直接还田,在这种粪污处理方式下,氮、磷的有效供给量分别占作物氮、磷需求量的10.49%和6.72%,表明天水市有足够的耕地消纳畜禽粪污;研究还发现:在固体粪污加工为商品有机肥,液体粪污沼气处理的方式下,粪肥养分损失率最低;各县区氮养分的替代率高于磷养分替代率;我市粪肥替代化肥潜力较大,应提高粪污资源化利用水平。研究结果可为天水市畜禽粪污资源化利用和确定养殖业发展规模提供理论依据。     

菜粉蝶Pain离子通道基因的克隆和功能研究

通过克隆十字花科蔬菜重要害虫菜青虫Pieris rapae瞬时感受器电位通道中的Painless（Pain）基因,实现它的体外功能性表达,为进一步研究其在鳞翅目昆虫中的生理功能提供重要依据。根据菜青虫的转录组数据,采用RT-PCR克隆菜青虫Pain基因得到完整开放阅读框;利用哺乳动物表达系统在体外表达菜青虫Pain离子通道。鉴定出菜青虫Pain基因是GenBank登录号为NW_019093434.1的序列。其完成开放阅读框由2850个核苷酸组成,编码949个氨基酸。预测蛋白分子量为108.3 kDa,理论等电点pI为5.37。预测该基因所编码蛋白序列有2个结构域,分别是包含8个锚蛋白重复序列的锚蛋白结构域和6个跨膜区的跨膜结构域。氨基酸序列比对结果显示菜青虫Pain和家蚕、帝王蝶、小菜蛾以及烟草天蛾Pain的序列相似度都高达70%以上,但与黑腹果蝇Pain的序列相似度仅有31%。进化分析结果显示菜青虫Pain离子通道和小菜蛾以及帝王蝶的Pain离子通道的亲缘关系最近。体外钙流检测结果表明,菜青虫Pain离子通道可被43℃缓冲液激活,这说明菜青虫Pain离子通道可以感受高温。     

Regulated deficit irrigation in green bean and watermelon greenhouse crops

Mediterranean greenhouse growers of watermelon and green bean crops tend to reduce slightly the soil water availability during the flowering phase to enhance the fruit number and yield, but without measuring the soil or the plant water status. This deficit irrigation strategy (RDI) was studied on two representative growth cycles of green bean and one of watermelon. In each case, a well-watered crop acted as control.In the three well-watered vegetable crops, soil water matric potential (SMP) values were between −20 and −30 kPa throughout most of the respective growth cycles. These values avoid water deficits in Mediterranean greenhouse vegetable crops. The watermelon under RDI presented similar SMP to the well-watered crop, except during the flowering period when it reached values of −50 to −60 kPa, which are similar to, or slightly lower than, those recommended to prevent water deficits for cucurbitaceae crops. The autumn–winter and spring cycles of green bean under RDI presented progressively lower SMP values from the vegetative phase to the first fruit setting than the well-watered crops, reaching minimum SMP values of around −55 kPa for the autumn–winter cycle and of −75 kPa for the spring one. These minimum SMP values are similar for the autumn–winter cycle and lower for the spring cycle than those recommended to avoid water deficits in green bean crops grown in medium-fine textured soils. Overall, mild water deficits during flowering of watermelon and green bean crops grown in Mediterranean greenhouses did not improve the final fruit number or yield. In the two spring cycles (watermelon and green bean) the RDI strategy reduced the aboveground biomass and yield, whereas in the autumn–winter green bean cycle the RDI strategy reduced the vegetative biomass but did not affect yield. SMP threshold values can, however, be used by growers as a tool for controlling the equilibrium between the vegetative and reproductive growth of greenhouse soil-grown crops.     

Effect of enhanced ultraviolet-B on allelopathic potential of Zanthoxylum bungeanum

The effect of enhanced ultraviolet-B on allelopathic potential of Zanthoxylum bungeanum was investigated. A significant inhibitory effect on germination rate of crop seeds under bioassay was observed at 25 g l⁻¹ and 50 g l⁻¹ by extracts from Zanthoxylum leaf both treated with enhanced ultraviolet-B radiation and untreated control. Medicago sativa and lettuce were more sensitive than radish to the extract from Zanthoxylum leaf treated with enhanced UV-B radiation, as the germination rates of M. sativa and lettuce were significantly reduced compared to control at 25 g l⁻¹ and 50 g l⁻¹, and so did alfalfa at 12.5 g l⁻¹. However, as for radish (Raphanus sativus) there was no significant reduction in germination rate at any concentration under bioassay compared to control. Content of UV-B absorbing compounds and total phenols in Zanthoxylum seedlings responded positively to enhanced UV-B radiation. The results suggest that the allelopathic potential of Z. bungeanum was generally improved under enhanced UV-B radiation.     

Response to drought and salt stress of lemon ‘Fino 49’ under field conditions: Water relations,osmotic adjustment and gas exchange

Drought and salinity are two of the most important factors limiting the lemon yield in south-eastern Spain. The effects of drought and salt stress, applied independently, on water relations, osmotic adjustment and gas exchange in the highest evapotranspiration period were studied to compare the tolerance and adaptive mechanisms of 13-year-old ‘Fino 49’ lemon trees, in immature and mature leaves. The study was carried out in an experimental orchard located in Torre Pacheco (Murcia). Three treatments were applied: Control, well-irrigated; drought-stress (DS), non-irrigated from 15th May to 7th July and salinity, irrigated with 30 mM NaCl from 1st March to 7th July. At the end of the experiment, only DS trees showed a decreased leaf stem water potential (Ψ_md). Under DS conditions, both types of leaf lost turgor and did not show any osmotic or elastic mechanism to maintain leaf turgor. Osmotic adjustment was the main tolerance mechanism for maintenance of turgor under salt stress, and was achieved by the uptake of Cl⁻ ions. Gas-exchange parameters were reduced by DS but not by salinity, stomatal closure being the main adaptive mechanism for avoidance of water loss and maintenance of leaf turgor. Salinity gave rise to greater Cl⁻ accumulation in mature than in immature leaves. The increase of proline in immature leaves due to DS indicates greater damage than in mature leaves.     

花吊丝竹对干旱胁迫的光合和生理响应

通过盆栽实验,研究了花吊丝竹在自然耗水的干旱胁迫处理下土壤含水量、叶片水势、叶片光合作用参数、叶绿素荧光参数以及相关酶类生理指标的变化。结果表明:(1)干旱胁迫下,土壤含水量与叶片水势显著下降,叶片的净光合速率、气孔导度和蒸腾速率均有不同程度下降,胞间CO2浓度呈先降后升的趋势,而气孔限制值则呈先升后降的趋势,说明轻度干旱胁迫下,气孔限制是花吊丝竹净光合速率降低的主要因素,重度干旱胁迫下,非气孔限制是净光合速率降低的主要因素。(2)花吊丝竹叶片光系统Ⅱ的实际光化学效率、表观光合电子传递速率和非光化学猝灭系数在胁迫后段(15~30 d)呈显著下降趋势,而叶片初始荧光在后期呈上升趋势,表明随胁迫程度加重,PSⅡ的结构受到较严重的损伤。(3)随干旱时间的延长,脯氨酸和丙二醛的含量均显著上升,而超氧化物歧化酶和过氧化氢酶的活性则先升后降,这表明随胁迫程度加深花吊丝竹细胞结构被破坏。综上所述,干旱胁迫环境下,花吊丝竹叶片光合作用和保护酶类均发生相应的变化,其自身能够提高叶片对光能的捕获能力、提升光能转化效率、增强叶片中的酶活性以及减少热能的耗散等形式,实现对干旱胁迫较强的忍耐性和较好的适应性。     

运用投影寻踪法建立苹果树蒸腾量的预测模型

[目的]运用投影寻踪回归分析法建立苹果树蒸腾量的预测模型,为更方便更好地预测苹果树蒸腾量提供指导。[方法]根据2009年5～9月气象站观测数据,对气温、相对湿度、风速、太阳辐射、大气压、土壤温度、叶温和水面蒸发量进行分析,并应用投影寻踪回归分析法建立了各气象因子与苹果树蒸腾量的预测模型。[结果]气象数据分析表明,大气水势随着气温增高呈减小的趋势,但随着气温降低和湿度增加而增加。气温、净辐射与作物叶水势均呈抛物线关系。随着净辐射的增大,作物消耗的水量增大,叶水势降低。由叶水势与土壤含水率关系可知,当土壤含水率减少时,苹果根系难以吸收到足够的水分,不能满足叶片蒸腾耗水的需求,导致叶片含水量偏低,叶水势也随着下降。苹果叶水势随着土壤含水率的降低而降低。[结论]运用投影寻踪回归分析法建立了气象因子对苹果树蒸腾量的预测模型,且预测精度较高。     

花生光合作用特性研究进展(英文)

花生是我国重要的油料作物和经济作物,该文从光照强度、温度、CO2浓度、水分胁迫和肥力状况对花生光合作用的影响,不同栽培模式对花生光合作用的影响以及光合效率与花生品种产量关系几个方面介绍了国内外的研究进展,旨为我国高产花生品种的选育和花生高产栽培提供技术依据。