Tree improvement effects on tree size distributions for Picea glauca and Picea mariana in New Brunswick,Canada

Abstract

Height and diameter distributions between improved and unimproved (checklot) seedlots for white spruce [Picea glauca (Moench) Voss] and black spruce [Picea mariana (Mill.) BSP] were compared using the two-parameter Weibull function. Individual tree height at age 5–15 years and diameter at breast height at age 15 years that were collected from two series of large-plot realized gain tests were used for this purpose. For both species, improved seedlots did not significantly (α=0.05) change the shape parameter of the distributions relative to their checklots, suggesting that an overall shape value will be adequate to predict tree size distributions of various improved seedlots. The most important finding was that seedlot influenced the scale parameter (related to the range of the distribution) significantly, but from a practical viewpoint, only those scale values of the higher rated seedlots (i.e. seedlots collected from a rogued seed orchard or superior families) were significantly higher (α=0.05) than those of the respective unimproved seedlot. The changes in scale value of the alternative improved seedlots relative to the checklot (Δ_Scale) were comparable in magnitude to the respective realized genetic gains, suggesting that tree improvement effects on the scale value can be adjusted by realized genetic gains. The results also suggest that site and age significantly affected the scale value; in general, Δ_Scale became larger at earlier ages or on better sites. The findings reported here will be used in the development of yield functions for genetically improved white and black spruce in New Brunswick.     

羔羊30日龄早期断乳及代乳料研究

［目的］提高羊只的生产性能。［方法］根据母羊的泌乳曲线和羔羊的生长发育规律，配制标准营养水平（试验1组）和低于标准营养水平15%（试验2组）的代乳料对30日龄羔羊进行早期断乳试验，以正常断乳（90日龄）为对照，比较不同试验组羔羊的日增重和饲料转化率及母羊的发情情况。［结果］试验1组和试验2组羔羊日增重和料重比均高于对照，30-90日龄2组羔羊的日增重分别为164.6、159.4 g，分别与对照（日增重118.7g）达到极显著和显著差异水平；试验1组和试验2组母羊发情较早，分别为51、54 d，对照组母羊平均发情期为66 d。［结论］羔羊早期断乳可使母羊的发情提早12-15 d。     

油松优树子代测定及遗传增益的初步研究

通过对５３０株油松优树子代林内８２９个家系（次）生长疸的测定，初步选出了较为优良的油松家系，并对不同来源的优树家系和单株的树高及地径的遗传率进行了估算。     

荷斯坦育肥牛日粮中添加碳酸氢钠的增重效果

荷斯坦育肥牛日粮中添加５０ｇ碳酸氢钠，观察增重效果，试验期５０ｄ。结果表明，试验组牛头均日增重比对照组提高１８．０％，差异显著。     

南方春大豆不同播季主要农艺性状的变化及其遗传研究

本文以１２个南方春大豆早熟品种（系）和１２个中熟品种（系）为材料，进行春，秋播试验，研究主要农艺性状的秋播变异率，遗传变异系数，遗传力和遗传进度，结果表明：１，两熟期组秋播变异率平均，除分枝起点为负值以外，其它１１个性状在２．３６％－５２．８８％之间，说明秋播对为结性状均有一定影响；熟期组之间各性状秋播变异率的大小亦存在较大差异，如秋播对早熟组株高，主茎节数，结荚节数，结荚高度，主茎荚数和百粒重的     

天农肥育牛用添加剂饲喂肉牛试验

选择年龄２～３岁，体重３００～４００千克的夏洛来杂公牛，西门塔尔杂交牛及黑白花公牛等品种牛共２０头，用天津农学院研制的“天农肥育牛用添加剂”进行了肥育试验，结果表明：试验组牛平均日增重１．２８２千克，对照组牛为１．０１２千克，试验组比对照组牛平均头日增重多０．２７千克，经ｔ经验两组牛日增重差异显著（Ｐ〈０．０５），经济收益比对照组头日净协１．９３元。     

Effect of stage of maturity of whole-crop barley on intake and liveweight gain by dairy steers differing in initial live weight

The effect of maturity at harvest of whole-crop barley for ensiling on intake and liveweight gain of dairy steers differing in initial live weight (LW) was evaluated in an experiment over two years. Light (104–120 kg) and heavy (402–419 kg) dairy steers were fed diets containing predominantly whole-crop barley silage harvested at the milk stage [dry matter (DM) content of 284 g kg⁻¹ and neutral-detergent fibre (NDF) concentration of 526 g kg⁻¹ DM] or the dough stage of maturity (DM content of 328 g kg⁻¹ and NDF concentration of 445 g kg⁻¹ DM) and supplemented with up to 1 kg of concentrate. Dry matter intake (g kg⁻¹ LW) was higher for whole-crop barley harvested at the dough stage than at the milk stage of maturity and the difference was greater in heavy than in light steers ( P <  0·001). Liveweight gain was higher and feed conversion ratio was lower for dough-stage compared with milk-stage silage ( P  <   0·05) but there was no interaction with size of steer. Whole-crop barley harvested at the dough stage of maturity promoted higher liveweight gains in dairy steers compared with whole-crop barley harvested at the milk stage due to a higher DM intake.     

蓝桉、直干桉重要材性性状的遗传参数和预期增益

在种子园育种区4个区组内,从蓝按和直干按中各抽30个家系对它们的纤维长度、木材密度的遗传力、遗传相关和遗传增益作了估算.蓝按纤维长度和木材密度的单株遗传力分别为,0.6745±0.0746和0.3546±0.1010;直干按两性状的遗传力分别为0.3416±0.1011和0.0670±0.0850.两树种的纤维长度与木材密度、树高和胸径的遗传相关系数均为正值,而木材密度与树高和胸径的遗传相关系数都是负数.为这两树种提出了选择的主要性状、选择方法和标准,还为高世代育种应注意的事项作了建议.     

The carbon budget of an adult <Emphasis Type="Italic">Pinus cembra</Emphasis> tree at the alpine timberline in the Central Austrian Alps

We investigated carbon (C) uptake and respiratory losses of an adult Pinus cembra tree at the alpine timberline throughout an entire year by means of an automated, multiplexing gas exchange system. These chamber measurements were then combined with biomass data for scaling up the C budget to the tree level. Integrated over an entire year, the cumulative C gain of the tree under study was 23.5 kg of C in 2002. The daily C balance was negative for 5 months and the estimated total wintertime respiratory losses were 9% of the amount of C fixed during the growing season. The total annual C loss of the tree consumed 55% of the annual net C gain and the remaining surplus was stored in new tissues (36%) and used for fine root growth (9%). Thus, the overall C budget of P. cembra at the upper timberline is balanced fairly well, although the C sink strength in fine roots is strongly limited owing to low root zone temperatures when compared to conifers at lower elevation sites.