Analysis of Multiple Binary Responses Using a Threshold Model

Several discrete responses, such as health status, reproduction performance and meat quality, are routinely collected for several livestock species. These traits are often of binary or discrete nature. Genetic evaluation for these traits is frequently conducted using a single-trait threshold model, or they are considered continuous responses either in univariate or in multivariate context. Implementation of threshold models in the presence of several binary responses or a mixture of binary and continuous responses is far from simple. The complexity of such implementation is primarily due to the incomplete randomness of the residual (co)variance matrix. In the current study, a multiple binary trait simulation was carried out in order to implement and validate a new procedure for dealing with the consequences of the restrictions imposed to the residual variance using threshold models. Using three and eight binary responses, the proposed method was able to estimate all unknown parameters without any noticeable bias. In fact, for simulated residual correlations ranging from ?0.8 to 0.8, the resulting HPD 95% intervals included the true values in all cases. The proposed procedure involved limited additional computational cost and is straightforward to implement independent of the number of binary responses involved in the analysis. Monitoring of the convergence of the procedure must be conducted at the identifiable scale, and special care must be placed on the selection of the prior of the non-identifiable model. The latter could have serious consequences on the final results due to potential truncation of the parameter space.     

氮肥及硝化抑制剂配合施用对石灰性土壤二氧化碳释放的影响

为研究施用氮肥对同时含有有机碳及无机碳石灰性土壤碳释放的影响,在陕西杨凌进行田间试验,比较了不同施氮量(0、160、220 kg·hm~(-2))及其与硝化抑制剂(DCD)配合(N160、N220及N160+DCD、N220+DCD)对土壤pH值、矿质态氮含量和二氧化碳(CO_2)释放量的影响。结果表明:施用氮肥显著降低了耕层土壤pH;配施DCD后土壤pH降低幅度小于未加DCD处理;加入DCD使氮肥的硝化过程推迟了约20 d;未加DCD处理的土壤CO_2释放量随施氮量增加而增加,试验结束时(施肥37 d后)土壤CO_2累积释放量最高达到167.1 g·m~(-2)。与N0处理相比,N160和N220处理的土壤CO_2累积释放量显著增加,增幅分别为20.9%和25.7%;N160+DCD和N220+DCD处理显著降低了土壤CO_2累积释放量,比对应相同施氮量处理分别降低了13.5%和11.0%。上述结果说明施用氮肥会同时影响石灰性土壤有机碳及无机碳的释放,施用氮肥引起的土壤无机碳的释放值得关注。     

Genetic dissection of grain yield traits in a large collection of spring wheat (Triticum aestivum L.) germplasm

Journal of Crop Science and Biotechnology - Understanding genetic architecture of a crop germplasm is necessary for designing a successful breeding program. Herein, we evaluated a large collection...     

Zinc Ameliorates Fruit Yield and Quality of Mangoes Cultivated in Calcareous Soils

Zinc (Zn) deficiency is frequently observed in mangoes grown in calcareous soils. Inherent inability of mango to extract sufficient Zn from the soil exacerbates this situation. Therefore, mitigating effects of Zn application was investigated on flowering, fruit setting, yield and quality of mango cv. Samar Bahisht Chaunsa growing in calcareous soils. The experiment consisted of five treatments: control—no Zn, soil application of 50 and 100 g ZnSO₄ per tree and foliar application of 0.5? and 1.0?% ZnSO₄ solution. Zn was applied twice in the 2^nd week of November, 2011 and 3^rd week of March, 2012, respectively. The experiment was repeated on the same dates during the next growing season. Zn application significantly increased number of flower panicle, fruits matured panicle, leaf Zn concentrations, fruit size, peel thickness, fruit weights at harvest and after ripening and fruit yield tree, whereas it reduced malformed panicles and early fruit drop. However, flower sex ratio and fruit set remained statistically unaffected. Similarly, fruit quality in terms of total soluble solids, flesh color, aroma, flavor and overall acceptability significantly improved as compared to control. Foliar application mitigated Zn deficiency more effectively than the soil application in calcareous soils.     

遥感数据结合地统计学方法在林业中的应用

在林业研究中,具有空间属性的林业数据分析、建模和预测越来越受到关注。遥感技术与地统计学方法相结合,提供了大尺度空间格局分析、森林资源动态监测和预测的方法。文中简单介绍了遥感技术与地统计学的方法和特点,从监测与分类、估计与模拟2个方面综述地统计学结合遥感技术在林业中的应用,并针对遥感数据结合地统计学方法在林业研究中存在的问题加以讨论。     

Denitrification and total fertilizer-N losses from an irrigated cotton field

 In a 2-year field study, denitrification loss was measured from an irrigated sandy-clay loam under cotton receiving urea-N at 158–173 kg ha^–1. An acetylene inhibition-soil core method was employed for the direct measurement of denitrification, considering also the N₂O entrapped in the soil. Taking into account the N₂O evolved from soil cores and that entrapped in the soil, a total of 65.7 kg N ha^–1 and 64.4 kg N ha^–1 was lost due to denitrification during the 1995 and 1996 cotton-growing seasons, respectively. Most (>70%) of the denitrification loss occurred during June–August, a period characterized by high soil temperatures and heavy monsoon rains. On average, 35% of the denitrification-N₂O was found entrapped in the soil and the amount of entrapped N₂O was significantly correlated with head space N₂O concentration and with water-filled pore space. ¹⁵N-balance during the 1996 growing season revealed a loss of 71.8 kg N ha^–1. It was concluded that a substantial proportion of the fertilizer-N applied to irrigated cotton is lost under the semiarid subtropical climatic conditions prevailing in the Central Punjab region of Pakistan and that denitrification is the major N loss process under irrigated cotton in this region. Received: 8 March 1999     

Comparative effectiveness of Pseudomonas and Serratia sp. containing ACC-deaminase for coinoculation with Rhizobium leguminosarum to improve growth, nodulation, and yield of lentil

Three plant growth-promoting rhizobacteria strains containing ACC-deaminase (Pseudomonas jessenii, Pseudomonas fragi, and Serratia fonticola) and Rhizobium leguminosarum were selected and characterized by conducting some experiments under axenic condition. The selected isolates had the potential to improve the growth of lentil seedlings under axenic conditions. Pot and field experiments were conducted to evaluate the potential of these selected strains for improving growth and yield of lentil under natural conditions. A classical triple response (reduction of stem elongation, swelling of hypocotyle, and change in the direction of growth) bioassay was also conducted to evaluate the effect of high ethylene concentration on the growth of etiolated lentil seedlings, and the performance of coinoculation was evaluated to reduce the classical triple response in comparison with cobalt (Co²⁺), a chemical inhibitor of ethylene. Results showed that coinoculation of Pseudomonas and Serratia sp. with R. leguminosarum significantly increased the growth and yield of lentil. However, synergistic/coinoculation effect of P. jessenii with R. leguminosarum was more pronounced compared to that with P. fragi and S. fonticola. It increased the number of pods per plant, number of nodules per plant, dry nodule weight, grain yield, and straw yield up to 76%, 196%, 109%, 150%, and 164% under pot and up to 98%, 98%, 100%, 82%, and 78%, respectively, under field conditions as compared to uninoculated control. Similarly, combined inoculation significantly increased N concentration of grains under both pot and field conditions. The results from classical triple response assay showed that the effects of classical triple response decreased due to coinoculation in etiolated lentil seedlings and due to a decrease in the ethylene concentration. It is suggested that the strategy adopted by Pseudomonas sp. containing ACC-deaminase with Rhizobium to promote nodulation and yield by adjusting ethylene levels could be exploited as an effective tool for improving growth, nodulation, and yield of lentil.     

Improving the Drought Tolerance in Pistachio (Pistacia vera) Seedlings by Foliar Application of Salicylic Acid

Gesunde Pflanzen - Pistachio (Pistacia vera L.) is an economically important nut crop that is prone to drought stress since it is mainly produced in arid and semi-arid regions. Considering...