有益菌根真菌及其互作对带叶兜兰试管苗生理生长的影响

为探讨菌根真菌的互作效应,筛选协同互作模式组合,对从野生兜兰新鲜营养根中分离、筛选出的3种菌根真菌（PF02、PF06和PF07）,采用单菌接种、双菌混合接种和三菌混合菌种等7种接种方式,开展菌−苗共生培养,筛选出优势菌株PF02和PF07,揭示在实验室环境下接菌方式与接种效应之间的相互联系,分析菌根真菌互作对带叶兜兰植株生长和生理的影响。结果表明：显示菌根真菌互作对宿主植株的生物量、保护酶活性及叶绿素总量具有较好的正向效应。3种双菌混合接种方式PF02−PF06、PF02−PF07及PF06−PF07均能有效促进带叶兜兰生物量增长,尤其是PF02−PF06接种方式,抗氧化酶POD、超氧化物歧化酶SOD、过氧化氢酶CAT活性及叶绿素总量提高显著。选择优化的接种方式,以及能够协同促进、达到共生平衡的最佳接种方式组合,最大限度发挥菌根对宿主植物的益生作用。     

Effect of Steeping Conditions on Wet-Milling Characteristics of Hard Red Winter Wheat

A batch-wise small-scale wet-processing laboratory for whole wheat kernel has been designed and constructed to produce wheat starch and gluten from wheat grains. Hard red winter wheat kernels were steeped in three steeping media: SO₂ solution, lactic acid, and hydrochloric acid. Acid concentrations of 0.1, 0.3, and 0.5%, were used for SO₂ solutions and hydrochloric acid, and 0.1, 0.6, and 3.0% for lactic acid. After 16, 20, and 24 hr of steeping, the wheat was wet-milled. Yields and protein contents of wet-milling fractions were compared. Both high concentration of steeping media and long steeping time increased the starch yield and decreased the protein contents of the starch. However, the steeping time and acid concentration could be reduced from 24 to 20 hr and from 0.5 to 0.3%, respectively, without any statistically significant difference in starch yields or protein contents of the starch. Consistency and color of the starch were affected by both steeping time and acid concentrations of steeping media.     

Forest biomass and root–shoot allocation in northeast China

Temperate and boreal forests act as major sinks for atmospheric CO₂. To assess the magnitude and distribution of the sinks more precisely, an accurate estimation of forest biomass is required. However, the determinants of large-scale biomass pattern (especially root biomass) are still poorly understood for these forests in China. In this study, we used 515 field measurements of biomass across the northeast part of China, to examine factors affecting large-scale biomass pattern and root–shoot biomass allocation. Our results showed that, Picea & Abies forest and coniferous & broadleaf mixed forest had the highest mean biomass (178–202 Mg/ha), while Pinus sylvestris forest the lowest (78 Mg/ha). The root:shoot (R/S) biomass ratio ranged between 0.09 and 0.67 in northeast China, with an average of 0.27. Forest origin (primary/secondary/planted forest) explained 31–37% of variation in biomass (total, shoot and root), while climate explained only 8–15%, reflecting the strong effect of disturbance on forest biomass. Compared with shoot biomass, root biomass was less limited by precipitation as a result of biomass allocation change. R/S ratio was negatively related to water availability, shoot biomass, stand age, height and volume, suggesting significant effects of climate and ontogeny on biomass allocation. Root–shoot biomass relationships also differed significantly between natural and planted forests, and between broadleaf and coniferous forests. Shoot biomass, climate and forest origin were the most important predictors for root biomass, and together explained 83% of the variation. This model provided a better way for estimating root biomass than the R/S ratio method, which predicted root biomass with a R² of 0.71.     

内蒙古典型草原草畜系统适宜放牧率的研究Ⅰ.以绵羊增重及经济效益为管理目标

(1)绵羊个体增重与放牧率呈线性负相关,个体最大增重临界放牧率,因季节不同而变化,随着个体增重与放牧率回归系数b绝对值的增大而降低,以始、终放牧期间所得临界放牧率最小,(2.04羊/hm²)。(2)公顷增重与放牧率的关系符合二次曲线,在达到公顷最大增重以前,随着放牧率的增大而增大,之后则随着放牧率的增大而下降,平均543羊/hm²。(3)公顷最大增重并不一定获取公顷最大利润,主要视买卖价格及其差值而定。(4)以冷蒿小禾草为主的退化草原,宜以个体最大增重的适宜放牧率作为管理标准,以使该类草原在利用中得以恢复。     

黄粉虫粪不同用量对制种黄瓜幼苗质量的影响

研究了营养土中不同黄粉虫粪搀入量对马坊营旱黄瓜幼苗生长的影响，结果表明：用黄粉虫粪与营养土按1：(160-320)(体积比)混配的基质进行黄瓜育苗，能促进幼苗生长，显著提高幼苗简单指标、相对指标和复合指标的值。     

磷化氢熏蒸对桔小实蝇氧化代谢体系的影响研究

为阐明磷化氢的生化毒理机制,本试验以重要检疫性害虫桔小实蝇(Bactrocera dorsalis Hendel.)为试虫,研究了25℃下磷化氢熏蒸对桔小实蝇3龄幼虫的毒力以及磷化氢熏蒸不同时间对桔小实蝇3龄幼虫氧化代谢体系的影响。结果显示：（1）25℃条件下磷化氢熏蒸桔小实蝇3龄幼虫48 h的LD50、LD90、LD99分别为0.28、0.37、0.46 mg/L;（2）磷化氢熏蒸抑制了桔小实蝇的呼吸作用;（3）随熏蒸时间延长,桔小实蝇体内过氧化氢含量和脂质过氧化水平不断上升,氧化压力逐渐增加;（4）磷化氢抑制了过氧化氢酶活性,最大抑制率为55.99%,增强了过氧化物酶活性、超氧化物歧化酶活性及抑制羟自由基能力,最大提高率分别为141.48%、130.21%、155.90%。本研究确认了磷化氢熏蒸杀灭桔小实蝇的有效性,其作用机制可能是通过抑制过氧化氢酶活性进而加剧活性氧积累实现的。     

不同密度杉木林内辐射与叶面积垂直分布对生长的影响

本文通过对八年生杉木人工林内太阳辐射与叶面积垂直分布的观测与研究,用计算机绘图与计算,得出以下结果:杉木叶面积的垂直分布和叶面积指数与密度有关,冠形因密度增加由圆锥形变为圆柱形,叶面积指数是先上升后下降。杉木林内辐射的消减随密度的增加而加剧,在冠层深3/4处趋于平缓,当郁闭度低于0.85时,林冠下辐射有回升。用累加叶面积指数分层计算林冠消光系数,可减少因叶片分布不均匀而产生的误差。用累计值计算辐射,可简化观测与计算。用辐射吸收率、叶面积指数、杉木个体生物量及年均生物增长量4个指标对杉木林生长作综合评价,八