不同辐射校正水平下水稻植被指数监测对比分析

归一化植被指数(NDVI)是反映植被长势特征的重要参数之一。获取准确的植被指数对揭示植被长势变化等定量遥感分析至关重要。基于不同辐射校正水平(辐射定标与大气校正),分别利用Landsat ETM+影像的灰度值(DN)、表观(TOA)反射率与地表(Surface)反射率计算相应NDVI,并根据鄱阳湖区野外定点观测数据,从农田、景观尺度揭示不同辐射校正水平下水稻生育期内NDVI动态变化特征。结果表明,根据DN、TOA反射率与Surface反射率提取的NDVI基本上可以反映出年内水稻不同熟制种植信息变化特征,即移栽期NDVI处于谷值,孕穗抽穗期NDVI达到峰值。但相应NDVI逐渐增加,且波动范围逐渐增大。就不同熟制水稻生育期而言,根据DN值计算并构建的NDVI曲线差异较小,而根据TOA反射率与Surface反射率反演的NDVI曲线差异明显。在植被定量遥感研究中,通过大气校正反演地表反射率计算植被指数相对客观准确。     

Stationary versus Fluidized-Bed Drying of High-Moisture Paddy with Rest Period

Drying of high-moisture paddy was examined experimentally under stationary and fluidized bed with and without intervening rest periods. Introduction of a rest period between first and second stage of drying improved drying rate and lowered the energy requirement and increased head rice yield. Fluidization further improved the overall drying process. A single-term drying diffusion equation was suitably fitted to first, rest, and second stage drying data of fluidized and stationary bed by applying nonlinear regression method and effective diffusion coefficients were evaluated. During the period of rest stage, paddy grain released a considerable amount of moisture as an effect of residual grain temperature. An appropriate moisture ratio at which resting should start and the length of resting were evaluated by measuring changes in relative humidity in the headspace of mass of paddy and also from the diffusion coefficient values obtained from the experimental drying data. Resting duration between 75 and 90 min at moisture ratio around 0.715 was found suitable for overall good performance in both fluidized and stationary bed drying. A considerable amount of energy (21–44%) can be saved by providing a rest period from 30 to 120 min between the two stages of drying. Fluidization further reduces (≈ 50% against continuous drying under stationary bed) the energy requirement. No significant difference was found in head rice yield obtained from fluidized and stationary bed experiments, though discontinuing drying by providing intervening rest periods considerably improved the percentage head rice when compared with the results from continuous drying.     

Performance of phosphine in fumigation of bagged paddy rice in indoor and outdoor stores

Phosphine fumigation trials were carried out on bag-stacks of paddy rice to study the differences in gas loss rates and concentration–time (Ct) products achieved during the treatment of indoor and outdoor stacks. Stacks (89–132 t) were fumigated singly under 250 μm thick polyethylene sheeting, which was sealed with a double layer of sand-snakes to the concrete floor. Phosphine was applied as an aluminium phosphide formulation and the fumigations continued for 7 days. In the first experiment, stacks of paddy rice with moisture contents ranging from 12.2 to 13.7% were held in either indoor or in outdoor storage and subjected to fumigation at the rate of 2, 3 or 4 g of phosphine/tonne. The outdoor stacks held relatively low levels of phosphine with Ct products for the indoor stacks of 135, 171 and 294 g h/m³, respectively, whilst the corresponding values for the outdoor stacks were 70, 85 and 166 g h/m³ only. The average gas loss rate was 14.5% per day for the indoor stacks and 29.5% for the outdoor stacks. In the second experiment, old stacks of paddy rice inside a godown, one each with grains at 8.8 and 9.8% moisture content, were fumigated at 3 g phosphine/tonne. Release of phosphine was delayed and fumigant sorption was less and therefore higher Ct products of 204 and 216 g h/m³ were achieved. In the stacks built outdoors, the resident infestations of Rhyzopertha dominica, Cryptolestes sp. and Oryzaephilus surinamensis were completely controlled despite lower Ct products. On the other hand, in the stacks of old paddy, R. dominica survived the treatment. Subsequent testing showed that the population had a degree of resistance to phosphine.     

STUDY ON BEHAVIOUR OF CR FORMULATION OF THIOBENCANB IN A MODEL PADDY FIE

ＳＴＵＤＹＯＮＢＥＨＡＶＩＯＵＲＯＦＣＲＦＯＲＭＵＬＡＴＩＯＮＯＦＴＨＩＯＢＥＮＣＡＮＢＩＮＡＭＯＤＥＬＰＡＤＤＹＦＩＥＬＤＳｕｎＪｉｎｈｅ（孙锦荷）；ＬｉＸｉｎｇｍｉｎｇ（李兴明）；ＣｈｅｎＺｉｙｕａｎ（陈子元）ａｎｄＺｈａｎｇＱｉｎｚｈｅｎｇ（张...     

Influence of straw mulching on fertilizer nitrogen use efficiency,moisture conservation and herb and essential oil yield in Japanese mint (Mentha arvensis L.)

In a field study, the influence of organic mulches viz. paddy straw and citronella (Cymbopogon winterianus Jowitt) distillation waste on herb and essential oil yield and fertilizer N use efficiency in Japanese mint (Mentha arvensis L.) were examined for two years. Herb yield (dry weight) increased by 17 and 31% with paddy straw and citronella distillation waste, respectively over the use of no mulch. Essential oil yield also significantly increased due to mulching. A significant response to N was observed with 200 kg N ha^–1 in unmulched plots as against 150 kg N ha^–1 in mulched plots. Mulched soils have been observed to contain 2 to 4% higher moisture as compared to unmulched soils. Nitrogen uptake by plants increased by 18 and 25% over no mulch with using paddy straw and citronella distillation waste, respectively.     

TL-4化学镀Ni-P合金在水田机械上的应用

水田机械的关键件，如水稻插秧机的移箱轴和推身杆等，均要求部件表面耐腐蚀抗磨损、有效高的硬度，特别是水稻施肥机的施肥轴是合浸在化肥中进行放置工作的，要求耐蚀非常严格。经采用ＴＬ－４化学镀Ｎi－Ｐ合金工艺对部件进行表面处理达到抗磨耐腐蚀和硬度要求，该工艺沉积速度快、镀液稳定，且施镀条件宽松、取材方便、成本低。镀层中磷含量在１２％左右，其结构为非晶态合金。镀层致密、光洁，达到产品的技术要求。     

Hermetic storage with plastic sealing to reduce insect infestation and secure paddy seed quality: A powerful strategy for rice farmers in Mozambique

Rice is the world's most important staple food and the basis of the diet of the majority of the population. In small farm agriculture, the yields obtained in cereal production are usually low and losses, both in the field and during storage, are dramatically high, particularly in developing countries. In Mozambique, these aspects, together with an increased frequency of floods, are hindering advances in rice production. Aimed at contributing to the reduction of losses in stored rice, trials were carried out to compare the effectiveness of traditional raffia bags and of hermetic storage using single and double plastic bags concerning quantitative losses and seed quality, including germination potential, after three and six months of storage. Pest identification, insect populations estimates, percentage of weight loss, germination power and seedling vigor were evaluated. The results showed that, in descending order of density, Angoumois grain moth (Sitotroga cerealella Olivier), lesser grain borer (Rhyzopertha dominica F.), rice/maize weevil (Sitophilus zeamais Mostch. and Sitophilus oryzae L.) and red flour beetle [Tribolium castaneum (Herbst)] were the main insects infesting the rice. When compared to hermetic storage with both single and duplicate airtight bags, traditional storage presented statistically significant higher mean infestation density (30.63–53.94 individuals/kg in traditional and 0.71–3.50 individuals/kg in hermetic storage) and percentage of weight loss (3.03–3.44% in traditional contrasting with 0.27–0.47% in hermetic conditions). In traditional storage a significant 38.25% drop in the germination potential was also observed, attaining values below the established minimum tolerated in Mozambique (80%), while under hermetic storage, that reduction remained within the acceptable values of 13.9–17.5%. The distinct storage methods did not produce significant differences on the moisture content of the grain. These results demonstrate that the use of hermetic storage has resulted in a safe, pesticide-free, and sustainable storage method, suitable for rice seeds, with advantages over traditional bagging. The results presented here lead to propose hermetic storage to be adopted by paddy small farmers, in order to lever food security and income generation in the country.     

几种稻田土壤对铵的矿物固定的动力学与热力学研究

本文采用振荡平衡法研究了紫泥田、河沙泥、灰泥田及红黄泥4种稻田土壤对铵的矿物固定的动力学及热力学特性。结果表明,供试土壤对添加铵的矿物固定速度很快,随着固铵量增多,固铵速度下降,反应后24小时固定基本上达到平衡,不因土壤种类而异。数学拟合结果表明,以一级动力学方程和E lovich方程描述供试土壤对铵的矿物固定资料最优,抛物扩散方程也能较满意地描述实验结果,以零级方程的拟合效果最差。供试土壤对铵的矿物固定的热力学资料均能用一元Langmu ir吸附等温式、Freund lich吸附等温式和Temk in吸附等温式拟合,拟合结果均达极显著水平,但以一元Langmu ir吸附等温式的拟合结果最优,由一元Langmu ir吸附等温式可以求得土壤对铵的矿物固定的热力学平衡常数、最大固铵量以及固铵过程中的自由能变△G°。供试土壤固铵过程的自由能变△G°均为负值,说明供试土壤对铵的矿物固定为一自发过程,4种土壤固铵强度依次为紫泥田>河沙泥>灰泥田>红黄泥。     

不同利用年限的红壤水稻土中重金属元素含量研究

本文介绍了不同利用年限的红壤水稻土中重金属元素As、Cd、Cr、Cu、Ni、Pb和Zn的含量变化,利用年限分别为3、10、15、30和80年。研究结果表明,虽然红壤水稻土中不同的重金属元素含量的变化趋势有所差异,但总体上重金属元素含量随利用年限的延长而降低,并可能达到一个相对稳定的水平;施用未经处理的城市垃圾会导致水稻土中某些重金属元素含量明显升高;研究区的水稻土已发生Cd和Cu污染。     

钉齿式双滚筒轴流脱粒与分离装置的试验研究

利用自行研制的试验台,对切向喂入的钉齿式双滚筒轴流脱粒与分离装置进行多因素的性能试验,得出了滚筒线速度、导向板导角、喂入量同功耗、脱不净率、茎秆破碎程度、夹带损失率、总损失等性能指标的试验结果,明确了相互关系及影响,分析了脱出物沿轴向分布规律。