Does root-sourced ABA play a role for regulation of stomata under drought in quinoa (Chenopodium quinoa Willd.)

The Andean seed crop quinoa (Chenopodium quinoa Willd.) is traditionally grown under drought and other adverse conditions that constrain crop production in the Andes, and it is regarded as having considerable tolerance to soil drying. The objective of this research was to study how chemical and hydraulic signalling from the root system controlled gas exchange in a drying soil in quinoa. It was observed that during soil drying, relative g_s and photosynthesis A_max (drought stressed/fully watered plants) equalled 1, until the fraction of transpirable soil water (FTSW) decreased to 0.82 ± 0.152 and 0.33 ± 0.061, respectively, at bud formation, indicating that photosynthesis was maintained after stomata closure. The relationship between relative g_s and relative A_max at bud formation was represented by a logarithmic function (r² = 0.79), which resulted in a photosynthetic water use efficiency WUE_Amax_/gs$\text{WU}{\text{E}}_{A_{\text{max}}/g_{\text{s}}}$ of 1 when FTSW > 0.8, and increased by 50% with soil drying to FTSW 0.7–0.4. Mild soil drying slightly increased ABA in the xylem. It is concluded that during soil drying, quinoa plants have a sensitive stomatal closure, by which the plants are able to maintain leaf water potential (ψ_l) and A_max, resulting in an increase of WUE. Root originated ABA plays a role in stomata performance during soil drying. ABA regulation seems to be one of the mechanisms utilised by quinoa when facing drought inducing decrease of turgor of stomata guard cells.     

Response of Vitis vinifera cv. ‘Tempranillo’ to partial rootzone drying in the field: Water relations, growth, yield and fruit and wine quality

This paper reports the effects of irrigation amount and partial rootzone drying (PRD) on water relations, growth, yield and wine quality of Vitis vinifera cv. ‘Tempranillo’ during two consecutive years in a commercial vineyard with a deep, light-clay soil located in Requena, Valencia, Spain. Partial rootzone drying applied at two amounts (100% and 50% of the estimated crop evapotranspiration), was compared to conventional drip irrigation, and also to rainfed vines. Results showed that the effects of irrigation amount on yield and wine quality were different between years. In 2003 with low yield values (around 6.3 t ha⁻¹) irrigation did neither affect grape production nor wine quality. However, in the following year, with much higher general yield (17 t ha⁻¹), the high irrigation dose increased yield by 30% compared to rainfed vines and it also increased must total soluble solids and wine alcohol content. In both seasons, PRD did not significantly affect physiological parameters, nor growth, yield or fruit and wine quality, when compared to the same amount of water applied by conventional drip irrigation. Overall these results suggest that, under our experimental conditions, it was the irrigation amount rather than the system of application what affected vine performance, indicating the difficulties of successfully employing the PRD type of irrigation with a drip system in heavy and deep soils.     

农业灌溉节水潜力及回归水利用研究进展

目前,对农业灌溉节水潜力尚未形成一个统一、公认的概念,相应的评价和计算体系也没有很好地建立起来.对农业灌溉节水潜力方面的研究成果进行了全面的回顾总结,提出了存在的问题和以后研究的重点.指出不同尺度回归水重复利用的量化是合理计算真实节水潜力的关键.最后,对回归水重复利用研究计算方法进行了归纳总结,提出了考虑回归水重复利用率的灌溉节水潜力评价思路.     

比格犬胫神经皮层体感诱发电位正常值研究

为了测定比格犬胫神经皮层体感诱发电位(somatosensory evoked potential,SEP)的波形及其潜伏期和波幅的正常值。选用15只健康比格犬,在异氟烷吸入麻醉状态下,使用肌电诱发电位仪电刺激其胫神经,将自制参考电极和记录电极分别放置于头部Fz处和Cz处记录SEP波形。结果表明:15只比格犬刺激左右侧胫神经均可记录到清晰的双向SEP波。刺激左侧胫神经引发的波形潜伏期为P(21.71±1.978)ms、N(32.61±2.568)ms、P-N(10.90±1.338)ms,其变异系数分别为9.11%、7.87%、12.88%;波幅为(2.762±1.230)μV,变异系数为41.47%;刺激右侧胫神经引发的波形潜伏期为P(21.49±1.985)ms、N(32.55±2.359)ms、P-N(11.06±1.153)ms,其变异系数分别为9.24%、7.25%、10.24%;波幅为(2.634±1.092)μV,变异系数为44.55%。潜伏期和波幅左右侧差异均不显著(P0.05)。对正常比格犬胫神经皮层SEP的测定,获得了清晰的SEP波形及各波潜伏期和波幅的正常值,印证了潜伏期的稳定性优于波幅的稳定性,可以为实验室研究犬病理状态下的SEP和宠物临床应用SEP诊断疾病提供参考依据。     

滴灌控制土壤基质势对土壤水分分布和苜蓿生长的影响

采用在滴头正下20 cm深度处埋设负压计,分别设置-15、-25和-35 k Pa的土壤基质势控制滴灌,通过田间试验,研究了不同土壤基质势下土壤水分变化特点和紫花苜蓿的生长特性,分析了蒸发、降雨和灌水与土壤基质势之间的关系。从土壤剖面水分分布来看,整个生育期内-15 k Pa处理下的土壤剖面含水率整体集中在14%~15%,较-25和-35 k Pa处理的更为均匀,水分密集区域距离滴头最近;-15 k Pa处理下苜蓿株高达到41.7 cm,盖度为15.3%,生物量值达到了281.29 g/m~2,在所有处理中均为最高。     

西北干旱区节水灌溉效益及潜力分析——以新疆乌苏市为例

基于西北地区农业灌溉特点,以新疆乌苏市为例,分析当前的节水灌溉措施和效益,指出了其中的不足之处,并通过对该地农业节水途径的分析,定量计算了未来10年该地和新疆以及西北地区的节水潜力,同时提出几点有针对性的建议和改进措施,以求为广大西北地区农业可持续提供发展思路.     

刺蒺藜草在我国的适生区预测

本研究基于MaxEnt模型,依据气候、海拔、人类活动等不同层面的12个环境变量建立刺蒺藜草适生性预测模型,模型AUC值高于0.9,表明模型结果可靠。预测显示：我国刺蒺藜草非适生区占73.66%;低度适生区占18.24%;中度适生区占5.11%;高度适生区占2.99%。其中广东、广西、海南几乎全境,福建、台湾、云南的大部分地区为中、高度适生区,具有最大的传入定殖风险。通过预测模型可以看出,bio＿11（最冷季度平均温度）、hf＿v3geo（人类足迹）、bio＿18（最暖季度降水量）和bio＿04（温度季节性变化标准差）等4个环境变量对刺蒺藜草在某地适生产生重要影响。     

基于GIS的绿色农产品基地适宜性评价

建立和完善绿色农产品基地适宜性评价方法,提高评价结果的实用性和准确性,是实现农产品安全的根本保障。研究依据基地认证者、规划者、生产者3种评价主体实际需求,分别引入污染潜在风险指标和经济状况指标,建立面向不同评价主体需求的多种主导因子评价指标体系,并借助GIS的空间分析方法进行定量评价,最后以北京大兴区为例进行了案例分析研究。结果表明,基地与工矿企业距离、与居民地距离等潜在污染风险对基地适宜性限制大,且不同评价主体下建立不同指标体系使评价更具针对性,利用GIS功能可提高效率,评价结果可视化程度好,具有很强的