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1.
J. W. Claussen 《Forest Ecology and Management》1996,80(1-3):245-255
Current practices in many nurseries involve the germination of tropical rainforest seedlings in shaded conditions and transferral, at a later date, to environments with greater light intensities. Determination of the ability of these seedlings to acclimate to increased light intensities will allow seedling stock to be processed with maximum efficiency within the nursery. The acclimation abilities of three species, Agyrodendron actinophyllum, Cardwellia sublimis, and Flindersia brayleyana, commonly found in north Queensland's rainforests were investigated in this study. These particular species are highly valued for their cabinet timber qualities and are being reared in nurseries for use in reforestation trials and programs in north Queensland. Seedlings were initially raised in greenhouse conditions under two layers of shade cloth (16% of full sunlight) and then transferred into full sunlight at three different ages (3 weeks, 10 weeks, 14 weeks). Upon transfer, organ ratios and the direction of dry matter distribution was determined for each species and age group. Approximately 3 months after the seedlings were transferred, the acclimation ability of each species and age group was then determined. Dry matter distribution was found to change with age, irrespective of light environment. Individuals within a species with larger root systems and thicker or more dense leaves had a greater acclimation ability than those with smaller root systems and thinner or less dense leaves. Furthermore, individuals within a species whose dry matter distribution upon transfer was directed towards developing a large root system, and a small photosynthetic area and mass, had a greater acclimation ability than those whose dry matter distribution was directed away from such morphologies. Awareness of these relationships allows a better understanding of seedling response to gap formation in natural forests, and also allows plant nursery operators to make a more informed decision about when to move seedlings to environments with a higher light intensity. 相似文献
2.
依据干旱胁迫下数种植物幼苗体内游离脯氨酸、叶气孔、叶水量的变化,剖析了植物与环境因子、气孔因子、氧气因子、酶因子及能量因子之间的相互依存关系,提出了PRO积累系统(PAS)。认为水分胁迫下植物体内PRO的大量积累是氧化受抑和合成受激共同调控的结果。氧气最有可能为直接触发因子。 相似文献
3.
以从美国威斯康星大学引进的叶用芥菜胞质雄性不育系叶用4-4为母本,以泰国清迈大学选育出的8个优良叶用芥菜品种为转育父本,杂交后连续回交4代(BC4),再将BC4与优良叶用芥菜品种40R2-3-4配制8个杂交组合,其中2个组合(4-4 × 19-H-12)×40R2-3-4和(4-4 × 2R2)×40R2-3-4结球率为100%,产量比商用品种分别高34%和13%,比其亲本分别高25%和5%。 相似文献
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儿茶素对蝴蝶兰叶片离体培养褐变发生的影响 总被引:1,自引:0,他引:1
用0.3 g/L儿茶素处理蝴蝶兰叶片外植体,在MS+3 mg/L 6-BA(pH 5.8)培养基上培养4 d,外植体褐变率高于对照227.6%.用香草醛-盐酸溶液染色反应法发现鞣质分布在维管束和细胞间隙.叶片剪切的外植体(培养0 d)鞣质含量较高,培养4 d降低,8 d后再升高.儿茶素处理的外植体鞣质含量明显高于对照.在培养期间,儿茶素处理的外植体PPO、POD和PAL活性高于对照外植体,其中POD活性在第8天达到最大值,PPO和PAL活性在培养第12天达到高峰. 相似文献
6.
Development of sorghum downy mildew, incited by Peronoscleospora sorghi (Weston and Uppal) C.G. Shaw, on maize, sorghum and Johnson grass was investigated at two locations in Uganda during three seasons (1994 and 1995). More sorghum downy mildew developed on the Johnson grass and sorghum than on the maize at all locations and in all seasons. No significant differences were observed in sporulation of P. soghi on the three hosts. Leaf shredding occurred on the three hosts but was the least on maize. Cross-inoculation with both conidia and oospores was achieved on the three hosts. Since the fungal population formed oospores and sporulated readily on the three hosts, which is typical of the sorghum strain, the disease in Uganda is attributed to the sorghum strain. 相似文献
7.
黄瓜叶面积测量方法的评价 总被引:4,自引:0,他引:4
采用方格纸法、等腰三角形法及数码相机拍照法测定黄瓜叶面积。结果表明,采用这3种方法测定的结果差异不显著。综合考虑耗时、信息量、先进性等因素,数码相机拍照法为最优测定方法。 相似文献
8.
通过对196篇相关文献的1 043对数据进行全球荟萃分析,评估免耕条件下玉米籽粒产量、秸秆生物量和叶面积指数的变化,并探讨气候、土壤、管理因素对其影响程度和方向。结果表明,相较于传统翻耕,免耕总体上显著降低了玉米籽粒产量、秸秆产量和叶面积指数5.7%、4.1%和9.7%。然而,这种效应因气候、土壤和管理措施而不同。在相对干旱的气候环境(年平均气温为>15℃、年平均降雨<600 mm)和恶劣的土壤条件(土壤体积质量>1.4 g/cm3、土壤有机碳含量<5.8 g/kg、土壤全氮为<0.75 g/kg)下,免耕条件下玉米生产力(籽粒产量和秸秆生物量)水平相对更好。其中,土壤有机碳含量和土壤速效钾含量与玉米籽粒产量呈显著负相关,年平均降雨和土壤速效磷含量与玉米籽粒产量和秸秆生物量呈显著负相关,土壤体积质量与玉米籽粒产量和秸秆生物量呈显著正相关。此外,肥料的高效施用、多样化的种植模式(间作或轮作)、秸秆还田等管理措施能抵消免耕条件下玉米生产力的负效应。总体而言,气候土壤环境相对更恶劣的区域可以从免耕技术上获益更多,而合理的田间管理措施也可以为... 相似文献
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控制测量数据内业平差处理时,对于多边形控制网而言,以最小独立闭合环为单位进行平差。基于站点的角度外业观测数据,提出最小独立闭合环的计算机自动快速检索算法。 相似文献