A model to estimate economic weight of tree survival relative to volume production taking patchiness into account

Abstract

Economic weights are needed for genetic selection to weigh different traits in multitrait breeding. The aim of this study was to develop, for commercial forest species, a model for estimating economic weights of survival relative to volume production per unit area. The model takes the patchiness across a stand and the polygenic nature of the factors influencing survival into account and consists of three submodels. The first submodel calculates volume production and a patchiness coefficient, using a production area that is divided into smaller units or production cells. The patchiness coefficient is defined in the model as the variance of survival between the production cells. The second submodel calculates volume production as a function of survival and the patchiness coefficient. The third submodel is a threshold model, which transforms the genetic change in survival from the observable scale to the underlying (liability) scale, thus providing a measure of economic weight. The model behaviour was studied using growth functions for Pinus sylvestris L. in northern Sweden. Both the absolute value of survival and its patchiness coefficient affected the projected production per unit area. When survival was higher than 50%, the relative economic weight of survival increased with decreasing survival and an increasing patchiness coefficient. The relative economic weight of survival was found to be insensitive to changes in site index and harvesting age, but was clearly affected by different initial stand densities.     

Economic weight of tree survival relative to volume production in tree breeding: A case study with Pinus sylvestris in northern Sweden

Abstract

The primary aim of the study was to estimate economic weights of survival relative to volume production per unit area, and to analyse the observable impact of changing survival, for five different breeding populations of Scots pine in northern Sweden. The economic weights were calculated from the model previously presented by the authors. Data from genetic field trials associated with the breeding populations were used both to estimate economic weights and to analyse the validity of the model. The breeding populations used were chosen to encompass a range of climatic conditions. The effects on the estimates of economic weights of increasing harshness (expressed as decreasing temperature sum), actual levels of both survival and patchiness of survival, and different initial stand densities were also analysed. The results showed that an appropriately parameterized model can be used to estimate economic weights for Scots pine in northern Sweden. Both the economic weight of survival and the observable impact of changing survival varied markedly between the studied breeding populations. Decreasing temperature sum had no trend with increasing economic weight of survival whereas decreasing survival and increasing patchiness of survival increased the estimated economic weight of survival more than three-fold.     

Selection indices for improving selection efficiency in Indian mustard

In Indian mustard (Brassica juncea L. Czern & Coss), a major oilseed brassica crop, oil yield is the ultimate trait of economic value, which is determined by seed yield (SY) and oil content (OC). SY, the end product of many complex biological processes, is influenced by many traits, such as plant height (PH), branch number, siliqua number, seed weight, seed size and pod length. It is difficult to accurately select for high-yielding genotypes based exclusively on SY, neglecting other yield-determining traits in commercial breeding programs. Therefore, it is desirable for breeders to simultaneously improve several traits of economic importance, most of which are quantitative in nature. The purpose of the present study was to develop selection indices for simultaneous selection of multiple quantitative traits to enhance selection efficiency of the mustard breeding program of Punjab Agricultural University (PAU) located in Abohar, Punjab. A set of 487 diverse mustard genotypes, comprising germplasm accessions of Indian and European origin, advanced breeding lines, landraces, and cultivars, was evaluated using an alpha lattice design for 2 years (2015–16 and 2016–17) at the Regional Research Station of PAU, Abohar, District Fazilka (the major mustard-growing region of the Punjab state). Data on PH, main shoot length (MSL), number of primary branches (NPB), number of secondary branches (NSB), number of siliquae on main shoot (NSMS), siliqua length (SL), number of seeds per pod (NSP), 1000-seed weight (TSW), SY on a plot basis and OC were recorded. To compute selection indices, economic weights, as determined via path coefficient analysis, were assigned to major yield-determining traits. Out of eight recorded agronomic traits, four traits, viz., NSMS, TSW, NSB and NPB, had larger direct effects on SY than other traits, and hence were assigned relative economic weights of 0.60, 0.20, 0.12 and 0.08, respectively. Selection indices were computed using different combinations of traits via Kang_SASPath computer program. When seven traits were used in a selection index (PH, NPB, NSB, NSMS, SY, TSW and MSL; or PH, NPB, NSB, NSMS, SY, TSW and OC), expected genetic advance (GA)at 5% selection intensity was about the same (9.55; selection efficiency or SE = 163% compared with selection based on SY alone).The GA was 9.46 (SE = 161%)for five traits, viz., NPB, NSB, NSMS, SY and TSW; and 9.30 (SE = 159%)for four traits, viz., NPB, NSB, NSMS, and TSW. These GAs were compared with the GA for SY only, which was 5.90 (benchmark; SE = 100%). We concluded that simultaneous selection based on multiple traits was always more efficient than selection based on SY alone. As there was only a small difference between the GA based on four traits (SE = 161%) and GA based on seven traits (SE = 163%), we suggest that mustard breeders use the parsimonious combination of four traits, viz., NPB, NSB, NSMS, and SY, to enhance SY and, consequently, oil yield in mustard.     

加权空间模糊动态聚类算法在土壤肥力评价中的应用

 【目的】改进和提高空间模糊聚类算法。【方法】首先利用层次分析法得到各属性的权值,然后将权值与空间模糊动态聚类法相结合,最后利用概率统计中的F分布来确定最佳分类,以提高空间模糊聚类算法的智能性。【结果】加权空间模糊动态聚类算法与基于模糊等价关系的传递闭包方法进行比较表明,当λ取0.993时,F值最大,分类效果最好。此时,加权的F值为4.898,未加权的F值为2.957,说明加权的类间的差距比未加权的明显,即该算法聚类准确率要明显高于未加权的模糊聚类算法。【结论】将其改进的算法运用到精准农业的土壤肥力评价中,试验结果与实际情况相符,证明了该算法的有效性。     

Some Production Characteristics of Sudan Desert Sheep under Range Conditions in North Kordofan,Sudan

The records on the flocks of sheep at El-Obeid Research Station during 1988–1990 were analysed using least-squares mixed-model procedures. The objective was to study some production characteristics of Sudan Desert sheep in North Kordofan, Sudan, in relation to the seasonal variation and husbandry systems. No significant differences (p>0.05) were found between sedentary and nomadic flocks in the number of ewes serviced and the conception, lambing or abortion rates. Mortality rates were significantly (p<0.05) higher in the nomadic flock. The breeding season had a significant effect on all the parameters measured. Higher conception (p<0.05) and lambing (p<0.01) rates were recorded for the rainy and late dry seasons. However, the highest ewe mortality (p<0.01) was in the rainy season. The highest (p<0.01) lamb weights at birth and at 30 days of age were recorded under the nomadic system. None the less, lambs kept under the sedentary system had somewhat higher weight gains from 60 to 150 days of age. Lambs born during the rainy season had the highest birth weights (p<0.05) and the highest weight at 30 days of age. However, the live weights from 60 to 150 days of age were significantly higher in lambs born in the late dry season. The highest lamb mortality was recorded in the lambs born in the rainy season. Lambs born under the nomadic system and during the rainy season had the highest (p<0.05) weights at 30 and 60 days of age, and also higher (p<0.01) mortality rates compared to the other flock×season combinations. It was concluded that the production characteristics of Sudan Desert sheep reflect the seasonal nutritional status and husbandry system. The effects of supplementary feeding on breeding and pregnant ewes, and on the performance of weaned lambs in the area should be studied. Moreover, the socioeconomic factors governing mobility in nomadic flocks should be thoroughly investigated.     

鲁西黄牛肉用品系育种目标性状经济权重计算

根据鲁西黄牛肉用品系的育种和生产实际,在基础母牛群体规模固定的二阶开放核心群育种生产体系下,构建了核心群和商品群中犊牛、青年母牛、青年公牛、成年母牛、成年公牛和育肥牛6个群体,包含断奶重、周岁重、成年母牛体重、育肥期日增重、胴体等级、屠宰率、初产年龄、产犊间隔和生产年限9个目标性状的利润函数模型。采用边际预算法计算目标性状的经济值,经贴现指数和遗传标准差校正后估算其经济权重。结果表明,6个群体体系中,每头母牛年利润为-1033.96元;9个目标性状经济值分别为:1.44元/kg,1.49元/kg,-3.02元/kg,1.81元/g,315.45元/级,66.85元/%,-0.54元/d,-4.43元/d,0.09元/d;相对经济权重分别为0.11,0.11,0.14,0.26,0.14,0.12,0.01,0.08,0.03。结果表明,鲁西黄牛从役肉兼用向专门化肉用方向选育,需要加强生长发育性状选择的同时,兼顾胴体性状和繁殖性状。     

Competition control in juvenile hybrid poplar plantations across a range of site productivities in central Saskatchewan,Canada

The response of hybrid poplar plantations established on former agricultural land in Saskatchewan to competition from weeds on a range of site productivities was studied. The short-term impact of competition control on the growth of juvenile trees and how tree responses to competition control differed across the productivity gradient was of particular interest, as was the determination of which resource was most highly competed for and was most important in determining tree growth. Eight sets of paired plots in juvenile hybrid poplar plantations were established in central Saskatchewan across a range of site productivities. In each pair, one plot had complete weed control (weed-free) while in the other plot weeds were allowed to grow. The best soil predictor of tree growth was soil texture, represented by a combination of the percentage silt and clay, with finer textures showing better growth. Competition control significantly increased tree growth on all sites with the benefit being greatest on the higher productivity sites. Soil water appeared to be highly competed for between trees and weeds and was a dominant resource controlling growth. For soil nutrients, nitrogen and phosphorous were highly competed for between trees and weeds. However, leaf phosphorous concentration of the weed-free plots had a strong positive relation to tree growth while nitrogen did not, indicating that when trees are free of competition they can access sufficient nitrogen from these soils.     

属性层次模型的决策方法与应用

在属性测度基础上,提出了相同对属性测试和属性判断矩阵,并由属性判断矩阵构成相对权重和合成权重。最后用ＡＨＭ方法讨论一实际问题。     

Multicriteria analysis for design of microirrigation systems. Application and sensitivity analysis

This paper presents a practical application of the DSS MIRRIG for the design of a microirrigation system for a citrus orchard in Algarve (Portugal). Several alternatives were considered using different emitter types (drippers, sprayers, pressure-compensating and non-pressure compensating emitters), different pipe sizes and layouts with and without pressure regulation valves, as well as different pressure head and discharge at the upstream end of the systems. This application is described and the ranking of alternative designs is analysed using the weights given by the farmer to the hydraulic, economic and environmental criteria. An analysis of impacts resulting from selecting different weights is presented aimed at understanding the sensitivity of the model in relation to those criteria. In addition, a sensitivity analysis is performed to test the robustness of the algorithms used for ranking with respect to changes in concordance and discordance threshold values, which show that the values selected by the model are those providing for a more clear ranking of design alternatives.     

基于带权值的模糊关联规则的土壤质量评价

Fuzzy association rules (FARs) can be powerful in assessing regional soil quality, a critical step prior to land planning and utilization; however, traditional FARs mined from soil quality database, ignoring the importance variability of the rules, can be redundant and far from optimal. In this study, we developed a method applying different weights to traditional FARs to improve accuracy of soil quality assessment. After the FARs for soil quality assessment were mined, redundant rules were eliminated according to whether the rules were significant or not in reducing the complexity of the soil quality assessment models and in improving the comprehensibility of FARs. The global weights, each representing the importance of a FAR in soil quality assessment, were then introduced and refined using a gradient descent optimization method. This method was applied to the assessment of soil resources conditions in Guangdong Province, China. The new approach had an accuracy of 87%, when 15 rules were mined, as compared with 76% from the traditional approach. The accuracy increased to 96% when 32 rules were mined, in contrast to 88% from the traditional approach. These results demonstrated an improved comprehensibility of FARs and a high accuracy of the proposed method.