利用短波红外高光谱成像技术检测洋葱酸皮病(Burkholderia cepacia)

酸皮病是一种重要的洋葱采后病害,对洋葱的采后生产造成了巨大的经济损失。本研究利用短波红外高光谱成像系统对洋葱采后酸皮病进行检测,分别从健康的和已感染酸皮病的洋葱上采集高光谱反射图像(950~1 650 nm),通过对两种洋葱的光谱进行主成分分析的结果表明,洋葱的颈部区域在1 070、1 400 nm波长下对酸皮病的发生最具指示性。采用两种最佳波长下获得的对数比率图像对两种不同的图像进行分析研究。第一种分析方法是利用全局阈值(0.45)将感染酸皮病的图像区域从对数比率图像中分离出来,通过对分离图像区域的象元素进行Fisher判别分析,可辨别出80%感染酸皮病的洋葱。第二种分析方法是从对数比率图像上获得三个参数(最大值、对比度及匀质性),再将这三个参数作为输入特征向量导入到支持向量机(Gaussian kernel,γ=1.5)中,利用这种方法,可辨别出87.14%感染酸皮病的洋葱。应用本研究结果可进一步开发出一种多光谱成像系统,用于洋葱包装流水线上酸皮病的检测。     

A QTL controlling low temperature induced spikelet sterility at booting stage in rice

Low temperature is a major abiotic stress for rice cultivation, causing serious yield loss in many countries. To identify QTL controlling low temperature induced spikelet sterility in rice, the progeny of F2, BC1F1 and BC2F1 populations derived from a Reiziq × Lijiangheigu cross were exposed to 21/15°C for 15 days at the booting stage, and spikelet sterility was assessed. For genotyping, 92 polymorphic markers from 373 SSR and 325 STS primer pairs were used. A major QTL was initially indentified on the short arm of chromosome 10 by selective genotyping using highly tolerant and susceptible progeny from F2 and BC1F1 populations. The QTL (qLTSPKST10.1) was validated and mapped by genotyping the entire F2 (282 progeny) and BC1F1 (84 progeny) populations. The results from the F2 population showed that qLTSPKST10.1 could explain 20.5% of the variation in spikelet sterility caused by low temperature treatment with additive (a = 14.4) and dominant effect (d = −7.5). From the analysis of 98 selected BC2F1 progeny, the QTL located in the 3.5 cM interval between S10010.9 and S10014.4 was further confirmed. Based on the studies of 3 generations in 2 years, it was clear that the QTL on chromosome 10 is a major determinant of the control of low temperature induced spikelet sterility at booting stage.     

1-methylcyclopropene increases storability and shelf life in climacteric and nonclimacteric plums

The effect of 1-methylcyclopropene (1-MCP) at three different doses (0.25, 0.50, and 0.75 microL L(-1)) on the ripening processes of a climacteric, cv. Santa Rosa, and a suppressed climacteric type, cv. Golden Japan, plum was studied. For both cultivars, positive effects were observed in terms of inhibition of ethylene production and delays of the physical, chemical, and biochemical changes associated with ripening. 1-MCP-treated plums were firmer with lower weight loss, reduced degrees Brix/titratable acidity ratios, and lower color changes during cold storage and subsequent shelf life at 20 degrees C than controls. For most factors, the effectiveness of 1-MCP was dose-dependent in Santa Rosa but dose-independent for Golden Japan.     

Tillage effects on microbial biomass and nutrient distribution in soils under rain-fed corn production in central-western Mexico

Quantifying how tillage systems affect soil microbial biomass and nutrient cycling by manipulating crop residue placement is important for understanding how production systems can be managed to sustain long-term soil productivity. Our objective was to characterize soil microbial biomass, potential N mineralization and nutrient distribution in soils (Vertisols, Andisols, and Alfisols) under rain-fed corn (Zea mays L.) production from four mid-term (6 years) tillage experiments located in central-western, Mexico. Treatments were three tillage systems: conventional tillage (CT), minimum tillage (MT) and no tillage (NT). Soil was collected at four locations (Casas Blancas, Morelia, Apatzingán and Tepatitlán) before corn planting, at depths of 0–50, 50–100 and 100–150 mm. Conservation tillage treatments (MT and NT) significantly increased crop residue accumulation on the soil surface. Soil organic C, microbial biomass C and N, potential N mineralization, total N, and extractable P were highest in the surface layer of NT and decreased with depth. Soil organic C, microbial biomass C and N, total N and extractable P of plowed soil were generally more evenly distributed throughout the 0–150 mm depth. Potential N mineralization was closely associated with organic C and microbial biomass. Higher levels of soil organic C, microbial biomass C and N, potential N mineralization, total N, and extractable P were directly related to surface accumulation of crop residues promoted by conservation tillage management. Quality and productivity of soils could be maintained or improved with the use of conservation tillage.     

Irrigation scheduling of plastic greenhouse vegetable crops based on historical weather data

Irrigation scheduling based on the daily historical crop evapotranspiration (ET_h) data was theoretically and experimentally assessed for the major soil-grown greenhouse horticultural crops on the Almería coast in order to improve irrigation efficiency. Overall, the simulated seasonal ET_h values for different crop cycles from 41 greenhouses were not significantly different from the corresponding values of real-time crop evapotranspiration (ET_c). Additionally, for the main greenhouse crops on the Almería coast, the simulated values of the maximum cumulative soil water deficit in each of the 15 consecutive growth cycles (1988–2002) were determined using simple soil-water balances comparing daily ET_h and ET_c values to schedule irrigation. In most cases, no soil-water deficits affecting greenhouse crop productivity were detected, but the few cases found led us to also assess experimentally the use of ET_h for irrigation scheduling of greenhouse horticultural crops. The response of five greenhouse crops to water applications scheduled with daily estimates of ET_h and ET_c was evaluated in a typical enarenado soil. In tomato, fruit yield did not differ statistically between irrigation treatments, but the spring green bean irrigated using the ET_h data presented lower yield than that irrigated using the ET_c data. In the remaining experiments, the irrigation-management method based on ET_h data was modified to consider the standard deviation of the inter-annual greenhouse reference ET. No differences between irrigation treatments were found for productivity of pepper, zucchini and melon crops.     

刺五加鲨烯合酶基因的表达及其对皂苷含量的影响

为了了解刺五加鲨烯合酶基因(squalene synthase,SS)的表达特点及其对刺五加中皂苷含量的影响情况,以GAPDH基因为内参照基因,采用实时定量PCR技术,分析了SS基因在刺五加不同生长发育时期不同器官中的表达量及茉莉酸甲酯对其表达的影响情况;还利用SPSS 17.0软件分析了SS基因的表达量与刺五加中皂苷总含量的相关性。结果表明,在刺五加的整个生长期中,SS基因的表达量呈现出"低—高—低—高—低"的变化趋势:萌芽期(4月26日)该基因的表达量最低,而盛花期(6月26日)该基因的表达量最高,为萌芽期的3.11倍;SS基因在刺五加根中的表达量显著高于茎、叶和叶柄中的表达量(P<0.05),其在茎中的表达量最低,仅为根中表达量的51.88%。茉莉酸甲酯可提高SS基因的表达量,但其与对照组的差异未达到显著水平。刺五加中的皂苷总含量与SS基因的表达量间呈现出同升同降的变化趋势,存在极显著的正相关关系(P<0.01)。文中初步判定,鲨烯合酶是刺五加皂苷生物合成的关键酶。     

Historical changes in land use influence current habitat preferences of large herbivores

Landscape Ecology - Predicting habitat use patterns is a key issue in the management of large herbivore populations. Particularly, indicators providing a model of the spatial distribution of a...     

Correction to: Individual based modelling of fish migration in a 2-D river system: model description and case study

Landscape Ecology - In the original publication of the article, the third author name has been misspelt. The correct name is given in this Correction. The original version of this article was revised.