Variation and inheritance of leaf angle, and its association with spot blotch (Bipolaris sorokiniana) severity in wheat (Triticum aestivum)

One thousand four hundred and seven spring wheat germplasm lines belonging to Indian and CIMMYT wheat programs were evaluated for their leaf angle and resistance to spot blotch caused by Bipolaris sorokiniana during three consecutive crop seasons, 1994–95, 1995–96 and 1996–97.Disease severity was recorded at six different growth stages beginning from tillering to late milk stage. Three crosses (M 3109 × Sonalika, HP 1808 × K 9006 and HD 2662 × K 9006) were made between genotypes with erect and drooping leaves. M 3109 was resistant, Sonalika susceptible while the other three lines possessed moderate resistance to spot blotch. Individually threshed F₂ plants were used to advance the generations. Leaf angle and spot blotch resistance were recorded in parents, F₁, F₃, F₄and F₅ generations. Leaf erectness in F₁ generation showed partial dominance. Evaluation of F₃, F₄ and F₅ progenies(120–150) revealed that leaf angle was under the control of few genes that appeared to be close to three. Germplasm lines with erect and semi-erect leaves displayed lower spot blotch severity than those having drooping and semi-drooping leaves. Lines homozygous for erect leaf posture in F₃,F₄ and F₅ generations showed significantly lower mean AUDPC than those with drooping leaves. A positive correlation (0.58) between leaf angle and AUDPC further indicated a positive influence of leaf erectness on severity to spot blotch disease. This revised version was published online in August 2006 with corrections to the Cover Date.     

Can salt stress-induced physiological responses protect tomato crops from ozone damages in Mediterranean environments?

The main route for ozone entry in plants is through the stomata. Consequently, environmental factors that may expose plants to any stress that will eventually lead to stomatal closure, will also reduce the rate of ozone entry into the plant and will possibly counteract ozone damages. In addition, several abiotic stresses activate the synthesis of antioxidant compounds, which are responsible for neutralizing toxic ozone derivatives. Due to this complex response, it is critical to assess how abiotic stresses and ozone toxicity will interactively affect plant growth and yield, especially in those areas, such as the coastal Mediterranean regions, where these types of stress and ozone exposure typically coexist. In this research we exposed tomato plants to salt stress in presence and absence of ozone to assess how salinity and ozone may interfere in terms of physiological responses and final yield. Plants grown in absence of ozone had a greater total biomass and higher yield compared to those grown in presence of ozone. Nevertheless these differences disappeared upon salinization. The reduced ozone damage in saline environment must be interpreted on relative terms, however, since salinity by itself caused a general inhibition of plant growth and yield. Based on these results, it was concluded that defining environment-specific ozone toxicity thresholds is necessary for developing reliable prediction models and/or assessing environmental safeguard levels.     

美洲黑杨新无性系木材细胞次生壁S_2层微纤丝角株内变异的初步研究

对６年生美洲黑杨无性系３６６、３７０，Ｉ—６９的Ｓ２层微纤丝角（ＭＦＡ）进行了研究。ＭＦＡ在不同无性系间，同一年轮的不同高度之间存在显著差异；而胸高部位径向变异不显著。同一年轮的ＭＦＡ随高度增加而降低；在径向，ＭＦＡ有从髓心向外逐渐减小的趋势。从无性系平均看，三无性系ＭＦＡ的大小次序为３６６＜３７０＜Ｉ—６９。     

贵南县露天甘蓝高产栽培技术

总结了贵南县露天蔬菜甘蓝高产栽培技术,包括生长特征、环境条件的要求、品种选择、整地播种、培育壮苗、定植、田间管理、病虫害防治、采收等方面内容,为贵南县菜农提高甘蓝栽培水平提供参考。     

竹材等离子体处理工艺优化及其在重组竹中的应用

采用响应面分析法考察了等离子体处理时间、功率、氧气介质压强等因素对炭化竹材表面润湿性的影响,以炭化竹材表面对PF树脂胶的接触角综合降低比作为评定指标,并将等离子体处理最佳工艺应用于重组竹的制造．结果表明等离子体处理最佳工艺为：时间82s,功率143W,氧气压强39Pa．在该工艺条件下表面接触角综合降低比为1．29．采用等离子体处理工艺使所生产的重组竹的弹性模量提高了26．59％,静曲强度提高了30．05％．电子扫描电镜分析结果显示,炭化竹材经氧等离子体处理后,表面因受到刻蚀而更加粗糙,表面湿润性提高．     

鳀鱼仔鱼饥饿试验及不可逆点的确定

2000年6月26日8-10时在35°00′N、121°00′E周围海域利用大型浮游生物网采集了大量鳀鱼的天然受精卵,11时受精卵开始孵化,12时收集初孵仔鱼进行饥饿试验。试验结果表明:在培养水温为23.0～24.8℃条件下,鳀鱼仔鱼的混合营养期仅1d多时间;仔鱼的不可逆点发生在孵化后第6天。鳀鱼后期仔鱼发育阶段都具有胸角这一形态特征,其胸角不能作为鉴别健康仔鱼和饥饿仔鱼的依据。这一发现补充和完善了鱼类学上关于仔鱼胸角的理论。     

湿地松枫香混交林林分空间结构特征研究

于湖南省杜家冲林场湿地松枫香混交林内设置4块具有代表性的样地进行调查,利用混交度、大小比数、角尺度3种结构参数,分析其林分空间结构特征。结果表明:该林分的平均混交度为0.678,属于中度偏强混交,说明该森林群落较为复杂与稳定;林分平均角尺度为0.475,林木空间分布格局为均匀到随机分布;样地平均胸径大小比数的取值范围在0.27~0.87之间,且湿地松(0.27)枫香(0.47)香樟(0.59)木荷(0.87),说明各树种在样地中分化较严重,湿地松和枫香在样地中较占优势。     

林分空间结构参数——角尺度的研究进展

角尺度作为测度林木空间分布格局的林分空间结构参数之一,具有检验能力强,调查简单易行等优点,现已得到了广泛应用。目前,有很多研究对这一参数应用不当并因此得出不合理的结论,究其原因是对角尺度理论基础缺乏了解。本文从角尺度概念的提出、相邻木个数的选择、标准角和随机分布阈值的确定、角尺度的应用等几个方面作详细阐述与总结,并指出目前的研究方向为空间结构单元大小对角尺度分析的影响及如何利用点抽样调查数据对种群分布格局进行检验等。