Combined use of optical and radar satellite data for the detection of tillage and irrigation operations: Case study in Central Morocco     

R. Hadria  B. Duchemin  T. Le Toan  G. Dedieu 《Agricultural Water Management》2009,96(7):1120-1127

The objective of this study is to present a new application of optical and radar remote sensing with high spatial (∼10 m) and temporal (a few days) resolutions for the detection of tillage and irrigation operations. The analysis was performed for irrigated wheat crops in the semi-arid Tensift/Marrakech plain (Central Morocco) using three FORMOSAT-2 images and two ASAR images acquired within one week at the beginning of the 2005/2006 agricultural season.The approach we developed uses simple mapping algorithms (band thresholding and decision tree) for the characterisation of soil surface states. The first images acquired by FORMOSAT and ASAR were processed to classify fields into three main categories: ploughed (in depth), prepared to be sown (harrowed), and not ploughed-not harrowed. This information was combined with a change detection analysis based on multitemporal images to identify harrowing and irrigation operations which occurred between two satellite observations.The performance of the algorithm was evaluated using data related to land use and agricultural practices collected on 124 fields. The analysis shows that drastic changes of surface states caused by ploughing or irrigation are detected without ambiguity (consistency index of 96%). This study provided evidence that optical and radar data contain complementary information for the detection of agricultural operations at the beginning of agricultural season. This information could be useful in regional decision support systems to refine crop calendars and to improve prediction of crop water needs over large areas.  相似文献   

Characterization by gas chromatography/mass spectrometry of sterols in saccharomyces cerevisiae during autolysis.     

Y Le Fur  G Maume  M Feuillat  B F Maume 《Journal of agricultural and food chemistry》1999,47(7):2860-2864

Yeast autolysis affects membrane stability and induces a release of vacuolar enzymes into the cell cytoplasm. Consecutively, it was important to study the evolution of sterol content in Saccharomycescerevisiae for a fourteen day period of accelerated autolysis. Unesterified and esterified sterols were analyzed both in the biomass and in the autolysis medium. Ten sterols were identified by gas chromatography/mass spectrometry. A second group of six sterols was separated and partially characterized. Among the first group of 10 sterols, a dehydroergosterol was identified as ergosta-5, 7,9(11),22-tetraen-3beta-ol, not yet charaterized in S. cerevisiae. Yeast autolysis induced a decrease of esterified sterol content, especially first intermediates in the sequence of the ergosterol biosynthesis, as zymosterol. In contrast, the yeast autolysis resulted in the release of a low quantity of sterols into the medium. At the end of the fourteenth day of autolysis, 0.015% of the total sterol content of the initial biomass was found in the medium.  相似文献   

Fish genotype significantly influences susceptibility of juvenile rainbow trout, Oncorhynchus mykiss (Walbaum), to waterborne infection with infectious salmon anaemia virus     

Biacchesi S  Le Berre M  Le Guillou S  Benmansour A  Brémont M  Quillet E  Boudinot P 《Journal of fish diseases》2007,30(10):631-636

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基于层次分析法的节水型社会评价研究   总被引：1，自引：0，他引：1  

徐海洋  杜明侠  张大鹏  潘乐  姚宛艳  韩栋 《节水灌溉》2009,(7)

以郑州市为例,根据实际情况,建立了节水型社会定量评价指标体系,采用层次分析方法对建立的评价指标体系做了评价,计算得出,2010年将初步建立节水型社会,2020年将全面建成与小康社会相适应的节水型社会.  相似文献   

最大熵技术分析湖南汽车工业发展优序     

王道平  李树丕 《湖南农业大学学报(自然科学版)》1998,25(6)

运用最大熵技术对湖南汽车工业部分重点企业进行了优序分析，并以此为基础，探讨了湖南汽车工业应优先发展的产品，针对性地提出了加快发展湖南汽车工业的若干建议。  相似文献   

Adaptability of water-plant cultivated in different mediums     

DING Hua-qiao  LI Fang  CHEN Tian-tian  CHANG Le  WU Tie-ming 《湖南农业大学学报(自然科学版)》2008,34(6)

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Changes in fatty acid and sterol composition during oogenesis in the pearl oyster Pinctada margaritifera     

Isabelle Vahirua‐Lechat  Frédéric Laure  Jean René LeCoz  Jean Pierre Bianchini  Mereani Bellais  Gilles Le Moullac 《Aquaculture Research》2008,39(16):1739-1746

The fatty acid and sterol composition of the oyster Pinctada margaritifera during oogenesis and in eggs was analysed. No major differences were observed during oogenesis, but the egg composition was significantly different from that of gonads. The amount of saturated fatty acids was the highest in eggs and the C16:0 predominant (P<5%); by contrast, the amount of 22:6(n‐3) was significantly lower (P<5%) than in gonads. No major differences were observed for the polar lipid (PL) composition during oogenesis. The main free sterols in gonads and eggs were cholesterol and brassicasterol. Among free sterols, the proportion of cholesterol diminished continuously from the beginning to the end of gonad maturation, and this decrease persisted in eggs after spawning. Cholesterol represented 40% to 55% of the sterol ester encountered in gonad and eggs. This study allowed us to investigate the fatty acid and sterol composition during oogenesis of the pearl oyster P. margaritifera, leading to a clearer understanding of the nutritional requirements of pearl oyster during the reproduction process.  相似文献   

Effects of dietary highly unsaturated fatty acids and astaxanthin on the fecundity and lipid content of pond-reared Penaeus monodon (Fabricius) broodstock     

Jian-Hua Huang  Shi-Gui Jiang  Hei-Zhao Lin  Fa-Lin Zhou  & Le Ye 《Aquaculture Research》2008,39(3):240-251

Five diets that contained fresh squid meat as the basic constituent and were supplemented with different amounts of highly unsaturated fatty acids (HUFA) and astaxanthin were fed to pond‐reared Penaeus monodon broodstock. Diet A was sole squid meat. Diets B and C were supplemented with astaxanthin 50 and 100 mg kg^?1 respectively. Diets D and E were supplemented with HUFA 5 and 10 g kg^?1 and astaxanthin 50 mg kg^?1 respectively. The result showed that the group fed diet E had the best reproductive performance in all experimental groups. It had a higher proportion of spawns (71.5%), spawning rate (0.047), a shorter latency period (7.7±0.3 d), higher absolute fecundity (× 10³) (361.6±5.5) and egg production/female (× 10³) (597.0±18.0) than all the other experimental groups. The fatty acid composition in broodstock diets strongly affected the tissue and fecundity of broodstock. Good correlations between the content of 20:4n‐6 in eggs and the fecundity (r²=0.6109) and egg production (r²=0.9876) of broodstock were found. On the other hand, 22:6n‐3 and DHA/EPA ratio was negatively correlated with the fecundity of broodstock (r²=0.5362, 0.8702 respectively). The result also showed that the balance between n‐3 and n‐6 fatty acid families, total polyunsaturated fatty acids and total saturated fatty acid and 20:5n‐3 (EPA) and 22:6n‐3 (DHA) may play vital roles in maturation and reproductive performance of P. monodon broodstock.  相似文献   

Interaction between energy level in the diet and environmental temperature on the utilization of energy in growing pigs   总被引：2，自引：0，他引：2  

J Noblet  J Le Dividich  T Bikawa 《Journal of animal science》1985,61(2):452-459

Thirty-two pigs weighing approximately 50 kg were maintained in respiration chambers to measure their heat production and the partition of energy retention between protein and fat deposition at two environmental temperatures (23 and 13 C) and with two energy levels in the diet: 3.39 (HE) and 2.92 (LE) Mcal ME/kg. From energy balance data, maintenance requirements (MEm) and the efficiency (k) of energy (ME) utilization for energy deposition were calculated for each treatment. For both diets, MEm averaged 122 kcal ME/kg.75 at 23 C, the rate of increase of MEm being 3.7 kcal ME/kg.75 for each 1 C decrease in the environmental temperature. At 23 C, k was higher with the HE diet (.81 vs .55) and similar for both diets (.78) at 13 C. At comparable ME intakes, heat production was higher with the LE diet at 23 C, and the rate of increase of heat production between 23 and 13 C was lower with the LE diet (1 kcal/kg.75) than with the HE diet (3 kcal/kg.75), resulting in similar heat production at 13 C for both diets. This resulted in an interaction (P less than .01) between temperature and diet on heat production. Protein retention was lower (P less than .01) at 13 C but unaffected by diet at both temperatures. This resulted in an interaction (P less than .01) between temperature and diet on fat retention. Consequently, energy of LE and HE diets was similarly utilized at 13 C, while at 23 C, the HE diet was better utilized. The comparison between these results and those obtained in growth experiments is discussed.  相似文献   

基于ELES模型的农民灌溉水价支付能力水平界定     

陈丹  陈菁  胡乐  陈运怀 《节水灌溉》2009,(7)

从支付能力的角度定量研究农民对灌溉水价的承受能力,采用扩展线性支出系统(ELES)模型,通过实例计算分析了农户总体收支及水费支出、农民基本消费需求支出和支付能力水平的界定标准等,并分析了支付能力的主要影响因素.结果表明:研究区域内农民年人均纯收入774元和1 300元是支付能力水平的分界线,无支付能力、有一定支付能力和有支付能力的农户分别占6.1%、9.7%和84.2%;支付能力较低的农户均以农业生产为主要收入来源;不同支付能力组之间农民年人均水费支出与平均水费支出均无显著差异;耕地面积、农业收入和非农业收入对农民支付能力具有显著的影响.  相似文献