Dark induced senescence as a tool in breeding wheat for optimum senescence pattern

Senescence can influence: (1) leaf area duration, (2) area of transpiringtissue and (3) translocation of nutrients – mainly nitrogen to grain.Therefore, selection for optimum senescence pattern might be efficient forimproving performance of wheat in a given environment. This study wasconducted to investigate the feasibility of a seedling test for estimatinggenotypic differences in senescence rate of wheat. We studied the responseof several wheat genotypes to dark exposure of seedlings, by measuring therate of chlorophyll loss in the first leaf. The rate of chlorophyll loss variedsignificantly among genotypes, the highest rate being more than double ofthe lowest. Linear regression accounted for most of the chlorophyll contentvariation during dark treatment in all cultivars. Significant correlation wasfound between the rate of chlorophyll loss following exposure to darknessand chlorophyll loss during aging in an environment relatively free ofdiseases and stresses. A good correlation was also found between theresponse of several genotypes to dark exposure and chlorophyll loss ofseedlings following starvation. We conclude that a seedling test for darkinduced senescence might allow an easy characterization of senescencepattern, allowing increased genetic progress in its optimization.     

火龙果茎段再生体系的建立

对火龙果茎段离体培养与植株再生过程进行了研究,建立了火龙果的再生体系。结果表明:愈伤最适诱导培养基为:MS+TDZ 0.4mg/L+KT 0.5mg/L+蔗糖30mg/L+琼脂8.8mg/L;丛生芽增殖最适培养基为:MS+TDZ 0.4mg/L+KT 1.0mg/L+BA 1.0mg/L蔗糖30mg/L+琼脂8.8mg/L;生根最适培养基为:1/2MS+NAA 0.3mg/L蔗糖30mg/L+琼脂8.8mg/L(pH 5.8)。     

不同苗龄“威廉斯B6”香蕉组培生根苗生产同批假植苗的研究

结合生根培养苗龄、假植基质等因素,研究了不同假植基质对不同苗龄香蕉组培生根苗假植成活率以及对假植苗假茎高度、叶片数、根系数、根系长度等生长指标的影响;同时研究了不同苗龄的瓶苗于不同季节在椰糠+珍珠岩中假植成活率的变化情况。结果表明:相同苗龄的香蕉组培生根苗在不同基质中假植成活率有显著差异,在椰糠+珍珠岩的混合基质中假植成活率最高;不同苗龄也是如此;结合假茎高度、叶片数、根系数、根系长度等生长指标认为椰糠+珍珠岩为最优假植基质,在这一基质中假植成活率可达92%～99%,能够满足不同苗龄香蕉组培生根苗在不同季节对假植基质的要求。     

不同基质配方对辣椒穴盘育苗质量的影响

在温室条件下,以泥炭土和珍珠岩为主要原料,按照不同的比例配合,对不同基质配方对辣椒幼苗生长发育的影响进行了研究。结果表明:辣椒幼苗在珍珠岩含量为25%的复合基质(泥炭土:珍珠岩=3:1)中表现最好,幼苗生长简单指标和复合指标均高于用其它3种配方;珍珠岩含量为50%的复合基质(泥炭土:珍珠岩=1:1)对辣椒幼苗生长有明显的抑制作用;综合分析表明,泥炭土与珍珠岩按照3:1配比作为辣椒穴盘育苗基质效果最佳。     

三角梅组培苗试管内外生根研究

以紫花三角梅和紫红重瓣三角梅组培苗为试材,研究其在试管内、外的生根情况.结果表明:试管内生根以1/4 MS+IBA 1.5 mg/L+NAA 0.05 mg/L处理的生根情况最好,生根率为92.53％,平均生根数量11条,平均根长4.75 cm;试管外的生根率为43％.     

H2O2诱导低温胁迫下草莓苗抗冷性研究

以草莓品种“丰香”为试材,研究了在低温胁迫下叶面喷施低浓度H2O2后草莓相关抗逆性生理指标的特性.结果表明:不同浓度H2O2处理抑制低温胁迫草莓叶细胞电解质渗透率和丙二醛(MDA)含量的增加,增强了草莓叶细胞内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)、脱氢抗坏血酸还原酶(DHAR)和谷胱甘肽还原酶(GR)的活性.     

不同栽培条件对红大戟块根产量的影响

以荫蔽度、种植密度、肥料为影响因子,块根产量为主要统计指标,采用正交实验设计,研究红大戟在类野生植被下的人工栽培技术.结果表明:影响红大戟块根产量的主次因素依次为种植密度、肥料、荫蔽度,并以种植密度30株/m2、有机肥2.5 kg/m、荫蔽度30％时产量最佳.     

Emergence timing affects root-collar diameter and mortality in loblolly pine seedbeds

Eight half-sib families of loblolly pine (Pinus taeda L.) were sown in a nursery. Total germination, speed and uniformity of germination, root-collar diameters, mortality, and percent cull were recorded by family. Families which germinated quickest attained the greatest average diameters at the end of the growing season. Low variability in date of emergence led to correspondingly low variability in seedling diameter. When data for all families were combined, seedlings which emerged earliest experienced the lowest mortality, had the largest diameters, and produced the fewest culls.     

广东林木种苗工程项目资金使用管理的问题与对策

概述了广东省林木种苗工程项目资金使用与管理现状,分析了其存在的主要问题,并提出解决问题的相关建议。     

Relative contribution of initial root and shoot morphology in predicting field performance of hardwood seedlings

Single and multiple linear regression techniques were used to explain the capacity of initial seedling root volume (Rv) and first-order lateral roots (FOLR) relative to shoot height, diameter, and fresh mass to serve as important indicators of stock quality and predictors of first- and second-year height and diameter on an afforestation site in southern Indiana, USA. This was accomplished for northern red oak (Quercus rubra L.), white oak (Quercus alba L.), and black cherry (Prunus serotina Ehrh) seedlings graded into four Rv categories at establishment. Field survival was high (85–97%) for all species. Initial diameter, height, fresh mass, and Rv provided similar predictive ability of second-year field response for absolute height (R² = 0.59–0.77) and diameter (R² = 0.50–0.73) for both oak species. Initial seedling Rv was a better predictor of field response than FOLR for both oak species, though not for cherry. Multiple-variable models accounted for a greater proportion of the total variation in seedling field height and diameter than did single-variable equations. The high R² (up to 0.95) of regression models suggests field performance of these species can be reliably predicted and confirms the importance of initial seedling morphology in dictating early plantation performance.