Measuring water stress in a wheat crop on a spatial scale using airborne thermal and multispectral imagery

A modified stress index is proposed that accounts for both chronic and acute water stress. Current trapezoid methods that use vegetation cover and temperature indices do not necessarily measure chronic conditions. The modified method describes the chronic stress as the ratio of actual crop cover to its potential expressed such that zero stress occurs when actual cover equals or exceeds the potential as determined by a simulation model. The advantage of such a definition is that in areas where full groundcover is rarely achieved, such as semi-arid regions, a more realistic and conservative stress condition will be observed. Airborne thermal and multispectral images were acquired at four growth stages of a wheat crop from a site in Victoria, Australia with experimental plots having rain-fed and irrigated regimes over two seasons (2005 and 2006). The theoretical basis of vector determination was adopted for trapezoidal extent per season. The relationship between such chronic stress and acute stress is explored and show that in any 2 years large differences between these stresses exist.     

贵州茶叶生产规模发展中的剪采矛盾

茶产业是贵州省重要的传统优势产业。本文就贵州茶叶发展现状与趋势、规模发展后将会带来的茶叶剪、采矛盾,提出了的相应缓解矛盾的措施和具体推广茶园剪采机械作业的想法。     

Spatial variability of bulk soil electrical conductivity in a Malaysian paddy field: key to soil management

On-the-go EC sensor is a useful tool in mapping the apparent soil electrical conductivity (EC_a) to identify areas of contrasting soil properties. In non-saline soils, EC_a is a substitute measurement for soil texture. It is directly related to both water holding capacity and cation exchange capacity (CEC), which are key ingredients of productivity. This sensor measures the EC_a across a field quickly and gives detailed soil features (1-s interval) with few operators. Hence, a dense sampling is possible and therefore a high resolution EC_a map can be produced. This paper presents experiences in acquiring detailed EC_a information that is correlated to other soil properties for precision farming of rice. The study was conducted on a 9 ha rice plot in MARDI Seberang Prai Station, Penang. The VerisEC3100 was pulled across the field in a series of parallel transects spaced about 15 m apart. The study showed that shallow and deep EC_a had high correlation and shallow EC_a had significant correlation to P. Deep EC_a had significant correlation to P, K and yield. Regression equations showed that N and P could be estimated by shallow EC_a but, pH, K and yield were better estimated by deep EC_a. This study was able to draw some basic ideas of nutrient zone management according to precision farming technique.     

Scaling up of a mechanistic dynamic model in a GIS environment to model temperate grassland production at the regional scale

Regional‐scale ecological processes are mediated by processes occurring at local scales. Spatially explicit models are needed to understand the broad‐scale consequences of a large number of local processes, driven by factors which are heterogeneous at a broad scale. A Geographic Information System (GIS)‐based mechanistic model, which can be used as a flexible tool to investigate the regional‐scale effects of changes in environmental factors on herbage production from a Lolium perenne sward, was developed and used to investigate the consequences of aggregating driving variables at different resolutions. The model allows rigorous scaling up of previously existing field‐based modelling approaches within a GIS context. The model's mechanistic approach allows flexibility in the simulation of the separate effects of environmental driving variables and of cutting regimes. The driving variables (temperature, solar radiation, available soil moisture and soil nitrogen status) are scaled up using geostatistical techniques. The model is used to evaluate weekly changes in herbage production under environmental conditions, variable both in space and time, under different cutting regimes. It is shown that, in this model, aggregation at 1 km² is a good compromise between accuracy and practical feasibility, and that, while ignoring heterogeneity over many square kilometres can induce large errors, their magnitude and direction also depend on the model response curve to an input variable. The results obtained were consistent with the known trends in influential environmental factors. The programming within a GIS makes the model flexible in its application and, therefore, makes it easy to apply at a variety of scales.     

Assessment of regional variation in climate on the management of dairy cow systems in Ireland using a simulation model

A dairy system simulator, Dairy_sim, was designed to assess the interactions between climate and management in spring‐calving milk production systems based on the grazing of grass pastures. The simulator comprises three main components: a grass herbage growth model, an intake and grazing behaviour model, and a nutrient demand model. The simulator was initially parameterized using the Irish National Dairy Blueprint. Sensitivity analysis indicated that the simulator was most sensitive to stocking rate, milk output per cow and nitrogen fertilizer inputs, but less sensitive to other variables. Field data from four grazing systems were used to test the simulator and it was concluded that Dairy_sim was suitable for evaluating the interaction of climate and management for rotational grazing dairy systems based on perennial ryegrass pastures with Friesian cows. The simulator, Dairy_sim, was then used to evaluate the effects of the regional climates of Ireland on system management. The results indicated that, between regions, herbage production at the same input of nitrogen may vary proportionally by 0·10 and that the length of the grazing season may vary by 0·25. It was concluded that the simulator could be a useful tool for developing region‐specific dairy production blueprints.     

Responses of C3 and C4 grasses to application of nitrogen and phosphorus fertilizer at two dates in the spring

In grasslands composed of C₃ and C₄ plants, a different pattern of response by the two photosynthetic types to fertilizer may change the floristic composition of the community. In this study, we evaluated the effects of an application of nitrogen (N) and phosphorus (P) fertilizer at two dates in the spring on the aerial growth of C₃ and C₄ grasses. Danthonia montevidensis and Stipa neesiana ( C₃), and Setaria geniculata and Sporobolus indicus (C₄), were selected from a native grassland of the Flooding Pampa, Argentina. Two consecutive experiments (early and late spring) were conducted in pots filled with the local soil. The C₃ grasses showed no response in aerial biomass, and only minor responses in aerial concentrations of N and P, numbers of leaves and tillers, and nutrient use efficiency to an application of P or N fertilizer. In contrast, their C₄ counterparts showed a consistent positive response. C₄ species performance was considerably influenced by date of fertilizer application in the spring. There was on average a 1·8 and a 2·5 increase in aerial biomass in early and late spring, respectively, to fertilizer application. The later date in spring was associated with higher ambient temperatures and it appeared that temperature rather than fertilizer application was the main limiting factor for C₃ species. It was concluded that the positive response in C₄ species to an application of P and N fertilizer indicates that the differences between C₃ and C₄ species were related to a higher demand to sustain greater growth rates in C₄ species.     

An alternative rotational stocking management designed to favour butterflies in permanent grasslands

Grassland butterflies are on the decline throughout Europe. We tested an ‘alternative rotational stocking’ (ARS) strategy based on theoretical and practical aspects of grassland ecology, designed to increase butterfly diversity while also meeting farmers’ production objectives. This management strategy implies taking animals away from one subplot of the rotation during the main flowering period. Its feasibility and benefits on butterfly diversity were tested by comparing ARS with continuous stocking (CS) in plots grazed by cattle at the same stocking rate: high in 2005 and 2006 then lenient in 2007 and 2008. At the high stocking rate, butterfly abundance (21·9 vs. 8·3, P < 0·01) and butterfly species richness (7·4 vs. 3·7, P < 0·001) were significantly higher in ARS than in CS plots, matching the increase in pasture flowering intensity and sward structural diversity. ARS was led according to the pre‐planned schedule in 2005, but in 2006, the number of heifer grazing days in ARS was reduced by 19% because of unfavourable spring grass growth. At the lenient stocking rate, ARS was less beneficial for butterflies (abundance: 17·4 vs. 13·0, P < 0·10; species richness: 5·9 vs. 5·2, P = 0·35) but would present less risk for farmers in terms of providing livestock with sufficient forage. Alternative rotational stocking thus has potential to be integrated into grassland‐based systems, but would require earlier grazing on the excluded subplot of the rotation in the event of unfavourable grass growth during spring.     

海南省农业部门能源消耗与农业生产总值的实证分析

利用自回归模型、脉冲响应函数、预测方差分解和格兰杰因果关系对海南省1988～2008年农业能源消耗与农业生产总值之间的关系进行实证分析。结果表明：农业能源消耗与农业生产总值变量序列之间存在高度线形关系,农业总产值对农业能源消耗具有明显的持续效应,但是增加能源消耗量,对农业总产值的影响不大,采取节约能源的政策并不会对海南省农业造成较大的冲击。     

高O_2与高CO_2气调包装对鲜切火龙果品质的影响

在高氧高二氧化碳(70%O2+30%CO2、50%O2+50%CO2)气调并结合CPP膜包装条件下,测定5℃贮藏15 d时,包装盒中CO2/O2浓度的变化、鲜切火龙果外在品质和营养成分的变化,探讨鲜切火龙果贮藏期间的品质变化规律。结果表明,高氧高二氧化碳气调包装能够避免无氧酵解,但在贮藏0~12 d,能促进鲜切火龙果的呼吸作用;而在整个贮藏期,高氧高二氧化碳气调能够明显地维持鲜切火龙果的硬度,减缓其甜菜红色素的降解;在贮藏的0~6 d,高氧高二氧化碳处理抑制可溶性总糖、总酚的消耗和加速总Vc分解,但对可溶性蛋白没有显著影响。因此,高氧高二氧化碳气调包装有利于鲜切火龙果营养品质的维持。结果可为鲜切火龙果商业化贮藏提供参考。     

小麦水分利用效率对CO2浓度响应的模型研究

为了定量研究水分利用效率(water use efficiency, WUE)对CO_2浓度的响应,在植物光合作用对CO_2响应模型的基础上构建了WUE(分为内禀水分利用效率和瞬时水分利用效率,即WUE_i和WUE_(inst))对CO_2(包括大气CO_2浓度和胞间CO_2浓度,即C_a和C_i)的响应模型,并应用新构建的模型对小麦(Triticum aestivum L.)测量数据进行了拟合。结果表明,新构建的模型不仅可以很好地拟合小麦叶片WUE对CO_2浓度的响应曲线(包括WUE_i-C_a、WUE_i-C_i、WUE_(inst)-C_a和WUE_(inst)-C_i曲线),而且还可以直接给出小麦的最大WUE_i和WUE_(inst)以及相对应的饱和C_a和C_i。以小麦WUE_i-C_a和WUE_(inst)-C_a曲线拟合结果为例,得到的最大WUE_i和WUE_(inst)分别为176.29μmol·mol~(-1)和8.65 mol·mmol~(-1),其对应的观测值分别为172.96μmol·mol~(-1)和8.62 mol·mmol~(-1);拟合得到的饱和CO_2浓度分别为1 410.52和1 399.73μmol·mol~(-1),对应的观测值分别为1 294.05和1 332.84μmol·mol~(-1)。拟合值与观测值之间均无显著差异。由此可见,新建模型拟合得到的这些参数与观测值高度相符,可用于植物WUE对未来CO_2增加响应规律研究。     

硝酸镧处理对短穗鱼尾葵幼苗耐寒性的影响

为探明硝酸镧对短穗鱼尾葵(Caryotamitis)耐寒生理指标的影响,用4个不同浓度的硝酸镧溶液(0、100、350、500mg/L)喷施盆栽短穗鱼尾葵叶片,经变温处理后检测各项耐寒指标。结果表明,超氧化物歧化酶(SOD)、过氧化物酶(POD)、丙二醛(MDA)、脯氨酸、可溶性蛋白和叶绿素的含量表现出明显的浓度效应,而且25℃恢复后幼苗叶片的各项耐寒指标的模糊隶属函数值分别为0.41、0.46、0.70、0.50,其中350mg/L硝酸镧溶液处理对提高短穗鱼尾葵幼苗的耐寒性具有显著的效应。     

The effects of nitrogen rate and the ratio of NO3:NH4 on Bemisia tabaci populations in hydroponic tomato crops

Nitrogen fertilization is one of the factors that influences Bemisia tabaci (Gennadius) population density. The aim of this study was to determine the effects of three N application rates (75, 205 and 335 mg/l) and three ratios of NO₃⁻:NH₄⁺ ions (92:8, 75:25 and 55:45) in standard nutrient solution (205 mg/l N) on the population density of B. tabaci. The experiments were conducted on spring-summer hydroponic crops of tomato. The effect of plant stratum on the whitefly population was also determined. The aggregation of B. tabaci adults as well as their oviposition rate was higher at 205 and 335 mg/l N than on plants grown at 75 mg/l N. By the end of the experiment (60 d after infestation), the number of nymphs on plants at 205 mg/l N was higher than on plants at 75 mg/l N. The number of pupae was lowest on plants supplied with 75 mg/l N. An increase in NH₄⁺ percentage in standard nutrient solution (from 25% to 45% of the total N) reduced adult population density and oviposition rate. The density of nymphs and pupae, at 60 d after infestation, was lower on the tomato plants grown at 75:25 and 55:45 NO₃⁻:NH₄⁺ ratios compared to the 92:8 ratio. The 75:25 and 55:45 NO₃⁻:NH₄⁺ ratios resulted in a higher incidence of blossom-end rot of tomato fruit, with a lower incidence of disorder at 75:25 than at the 55:45 ratio. Plant stratum influenced adult whitefly distribution in two years of the study. Middle stratum leaves were more attractive to adults in both years. The results demonstrate the effects of N fertilization (N rate and the ratio of NO₃⁻:NH₄⁺) and plant stratum on B. tabaci population density.     

逆境条件下烟草维生素B6存在形态的变化

维生素B6(VB6)是一类吡啶化合物的总称.以组培烟草为材料,采用高效液相色谱结合荧光检测技术,分析紫外线、低温、盐和弱光胁迫对烟草体内VB6各存在形态含量的影响.结果表明:逆境条件下,VB6各存在形态含量发生变化,其中以磷酸吡哆醛和吡哆醇含量升高最明显.     

玉米F0代子粒品质性状杂种优势的研究

用4个不同来源的自交系花粉分别与4个母本自交系杂交，分析杂交当代子粒中蛋白质、淀粉、赖氨酸含量和百粒重的当代杂种优势。试验结果表明：当代子粒的蛋白质含量、淀粉含量、赖氨酸含量和百粒重均存在当代杂种优势。其中F₀子粒中蛋白质当代杂种优势最高达54.1%。     

钾肥对玉米子粒灌浆的影响研究

研究钾肥对玉米光合特性、子粒灌浆特性及产量的影响。结果表明,施用钾肥对玉米果穗叶片的叶绿素含量、光合强度和玉米子粒灌浆及产量均有明显的促进作用。钾肥的适宜施用量在90～135 kg/hm²。     

Successful factors and activation theory/concept of water users’ organizations - based on the MWMS project in Thailand

This paper analyzes successful factors and develops theory/concept for the activation of the Water Users’ Organizations (WUOs) in the Modernization of Water Management System (MWMS) project in Thailand. The main successful factors are as follows: (1) improvement of irrigation facilities with the farmers’ participation; (2) providing an opportunity for discussions with farmers to enable the adjustment of water allocation through the establishment of an Integrated Water Users’ Group (IWUG) in the early stages of the project; (3) holding monthly meetings of the IWUG; (4) developing, operating, and monitoring the water allocation plan in cooperation with both farmers and government officials. That is to say, initiation of the facilities’ improvement and the establishment of the WUOs were performed concurrently. Moreover, the farmers participated from the beginning of the planning stage to the management stage. The MWMS project contributed to create a system that farmers can acquire and use irrigation water with reliability. Through this system, farmers could have ownership in their facilities, and then they participated in the operation and maintenance spontaneously. The most important thing is to give priority to a joint study process between the farmers and government officials for producing mutual understanding and building a good confidential relationship.     

海南休闲农业集群化发展思路及模式探讨

休闲农业集群是农业与旅游业相互结合而形成的一种新型产业集群,海南的休闲农业更适合走集群化的发展道路。从产业集群的理论与实践出发,指出目前在海南休闲农业集群化发展过程中仍存在一系列障碍因素,有针对性地从四个方面分析了海南休闲农业集群化发展的思路,在此基础上对海南休闲农业集群化发展的模式选择进行初步探讨。     

基于灰色关联理论的海南农业经济发展分析

运用灰色系统理论中关联分析方法,对海南农业经济发展进行分析。研究结果表明,各行业增加值与农林牧渔增加值的关联度排序为：γ旅游业＞γ商业餐饮业＞γ建筑业＞γ交通邮电业＞γ工业;农业内部各产业总值与农林牧渔总产值的关联度排序为：γ牧业＞γ种植业＞γ渔业 ＞γ林业。在此基础上,根据灰色关联的分析结果,为促进海南农业经济持续稳定发展提出了相应的建议。     

GA3处理对木薯类胡萝卜素生物合成的影响

木薯(Manihot esculenta Crantz)属大戟科木薯属热带作物,具有耐干旱贫瘠等特性,木薯叶片富含蛋白质,块根富含淀粉但是缺乏类胡萝卜素,是热带低收入人口的主粮.国家木薯产业技术体系"十三五"期间关于木薯产业问题指出,类胡萝卜素是粮饲化的重要指标,类胡萝卜素也是维生素A的前体物质.本文在前期研究中筛选到...     

Understanding the dynamics of neonicotinoid activity in the management of Bemisia tabaci whiteflies on poinsettias

The relative efficacies of registered label rates for foliar and soil drench treatments of imidacloprid and dinotefuran at preventing the establishment of Bemisia tabaci B biotype whitefly populations on newly infested poinsettia plants were evaluated. Pesticide levels within and on plant leaves were monitored for 10 weeks by ELISA and LC/MS in an effort to better understand the dynamics of neonicotinoid activity against this insect and to estimate insecticide concentrations needed to kill the nymphal and adult stages. While all treatments proved equally effective as a remedial measure for the control of the resident adult populations, thereby accomplishing the objective of foliar contact treatments, the dinotefuran soil drench application was the only treatment that provided multi-generational control of Bemisia populations.