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61.
62.
The use of saline waters is an option for the irrigation of salt tolerant ornamentals as competition for high quality water increases. However, despite the importance of ornamental shrubs in Mediterranean areas, salt tolerance of such species has received little attention. The aims of our investigation were to quantify the growth response and any injury symptom of 12 widely cultivated ornamental shrubs to irrigation with saline water and to investigate any possible relation with the concentration of Na+ and Cl− in the plants. Species were irrigated with different salinities (10, 40, and 70 mM NaCl) for a 120-day period. At the end of salt treatment, plants were sampled and dry biomass recorded; the relative growth rate (RGR) was also calculated. Root and leaf samples from each species were used to evaluate Na+, K+ and Cl− concentrations. Growth rates were significantly reduced in Cotoneaster lacteus, Grevillea juniperina and Pyracantha ‘Harlequin’, which also showed the highest percentage of necrotic leaves. The increasing external NaCl lead to an increase of Na+ and Cl− in roots and leaves of the different species, although less Na+ was accumulated than Cl−: growth reduction well correlated with the concentration of Cl− and/or Na+ in the leaves. The most sensitive species (i.e. C. lacteus, G. juniperina and Pyracantha ‘Harlequin’) had high concentrations of Na+ and/or Cl− in their leaves and also showed a decrease in their leaf K+/Na+ ratios. Even though other species (i.e. Bougainvillea glabra, Ceanothus thyrsiflorus, Leptospermum scoparium, Leucophyllum frutescens and Ruttya fruticosa) demonstrated a high ion concentration in their leaves, they could be considered relatively salt tolerant as there was little growth reduction and few symptoms of injury in the leaves. In some other cases (i.e. Cestrum fasciculatum, Escallonia rubra and Viburnum lucidum) the observed tolerance was related to higher ion concentration in the roots compared to the leaves, probably indicative of a limited transport to the shoots. Only in Eugenia myrtifolia was the absence of symptoms associated with a limited Na+ and Cl− uptake from the rhizosphere. 相似文献
63.
Paul C. Stoy Mathew Williams Mathias Disney Ana Prieto-Blanco Brian Huntley Robert Baxter Philip Lewis 《Landscape Ecology》2009,24(7):971-986
Transferring ecological information across scale often involves spatial aggregation, which alters information content and
may bias estimates if the scaling process is nonlinear. Here, a potential solution, the preservation of the information content
of fine-scale measurements, is highlighted using modeled net ecosystem exchange (NEE) of an Arctic tundra landscape as an
example. The variance of aggregated normalized difference vegetation index (NDVI), measured from an airborne platform, decreased
linearly with log(scale), resulting in a linear relationship between log(scale) and the scale-wise modeled NEE estimate. Preserving
three units of information, the mean, variance and skewness of fine-scale NDVI observations, resulted in upscaled NEE estimates
that deviated less than 4% from the fine-scale estimate. Preserving only the mean and variance resulted in nearly 23% NEE
bias, and preserving only the mean resulted in larger error and a change in sign from CO2 sink to source. Compressing NDVI maps by 70–75% using wavelet thresholding with the Haar and Coiflet basis functions resulted
in 13% NEE bias across the study domain. Applying unique scale-dependent transfer functions between NDVI and leaf area index
(LAI) decreased, but did not remove, bias in modeled flux in a smaller expanse using handheld NDVI observations. Quantifying
the parameters of statistical distributions to preserve ecological information reduces bias when upscaling and makes possible
spatial data assimilation to further reduce errors in estimates of ecological processes across scale. 相似文献
64.
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
65.
金光杏梅叶面积回归测算研究 总被引:3,自引:1,他引:2
以金光杏梅成熟叶片为试材,研究了叶长、叶宽与叶面积的关系.结果表明:叶长、叶宽与叶面积均呈正相关关系.叶长、叶宽与叶面积之间的相关系数分别为0.7084、0.8546,叶长和叶宽与叶面积的复相关系数为0.9868,在0.01水平下均达到了极显著水平.在此基础上建立了叶长(x1)、叶宽(x2)、叶长和叶宽与叶面积(y)之间的回归方程y=61.4140x1-2 480.6、y=28.7600x2-0.8546、y=17.6276x1+41.2594x2-1 078.4906,3个回归方程均可用于测算金光杏梅的叶面积,其中以叶长和叶宽与叶面积的二元回归方程测算结果更为精确.在具体应用中,可根据所要求的精确度进行选择. 相似文献
66.
67.
In an effort to increase the accessibility and functionality of shallow green roof systems, the ability of warm-season grasses to provide acceptable growth needs to be further investigated. In the current study, which was conducted during 2011 and 2012, three warm-season grasses (hybrid bermudagrass, Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy ‘MiniVerde’; seashore paspalum, Paspalum vaginatum Swartz ‘Platinum TE’ and zoysiagrass, Zoysia japonica Steud. ‘Zenith’) were established in outdoor lysimeters. The lysimeters were equipped with all necessary green roof layers placed below a coarse-textured substrate that comprised pumice, thermally treated attapulgite clay, peat, compost and zeolite. Half of the lysimeters had a substrate depth of 15 cm, while the other half had a substrate depth of 7.5 cm. Irrigation was applied at crop evapotranspiration (ETc). Measurements included determination of substrate moisture content, green turf cover (GTC) and leaf stomatal resistance. Significant differences were observed in the values of GTC among the three turfgrass species and the two substrate depths. Zoysiagrass exhibited the best adaptation at the lower depths of shallow green roof systems. At 15 cm substrate depth, zoysiagrass managed to sustain green coverage for the two study periods. In addition, it was the only turfgrass species that managed to perform well at the substrate depth of 7.5 cm. Seashore paspalum exhibited limited green cover at both substrate depths, while hybrid bermudagrass could provide acceptable green coverage only at 15 cm substrate depth. 相似文献
68.
基于Kinect动态手势识别的机械臂实时位姿控制系统 总被引:1,自引:0,他引:1
基于Kinect动态手势识别达到实时控制机械臂末端位姿的效果。位置控制信息的获取采用Kinect计算手部4个关节点在控制中的位置变动,数据噪声在控制中易引起机械臂误动作和运动振动等问题,为了避免噪声对实时控制的不利影响,采用卡尔曼滤波跟踪降噪。姿势控制信息通过采集手部点云经滤波处理后应用最小二乘拟合的方式获取掌心所在平面,运用迭代器降噪处理。系统通过对手部位置和姿势信息的整合、手势到机械臂空间坐标映射及运动学求解来实时控制机械臂末端位姿。实验结果证明,手势控制系统满足控制要求,简单、易于操作,机械臂实时响应速度快、运动准确。 相似文献
69.
白菜型冬油菜叶片结构和光合特性对冬前低温的响应 总被引:1,自引:0,他引:1
为明确白菜型冬油菜在冬前低温下叶片结构特征、光合作用特性及其抗寒性,本研究在0℃和–7.6℃自然低温条件下,选用白菜型冬油菜品种陇油7号(超强抗寒)和天油4号(弱抗寒),测定并比较其叶片气孔性状、解剖结构和光合、荧光参数的日变化等指标。结果表明,随着冬前温度下降,2个白菜型冬油菜叶片气孔密度、气孔面积、气孔周长、栅栏组织和海绵组织厚度均变小,细胞间隙变大,叶片变薄;P_n日变化呈"单峰"型曲线,无光合"午休"现象;叶片的P_n、G_s、T_r和CE均降低,而C_i均升高,说明是非气孔限制引起P_n降低。白菜型冬油菜在冬前低温条件下发生了光抑制现象,表现为F_m和F_v/F_m下降,F_o上升。与超强抗寒品种陇油7号相比,弱抗寒品种天油4号叶片气孔密度和气孔面积均较大,气孔总周长较长,叶片较厚,P_n、F_m和F_v/F_m均较高,说明冬前低温条件下,天油4号光合能力较强,光抑制程度较弱。白菜型冬油菜在冬前低温条件下的叶片气孔密度越大、气孔面积越大、气孔周长越长、叶片及栅栏组织和海绵组织越厚,光合能力越强,地上部生长越旺盛,品种抗寒性越差。本研究为冬油菜抗寒种质创新和育种提供了部分理论支撑。 相似文献
70.
利用离散趋近律设计的滑模控制可有效抑制滑模控制中的抖动现象,但其抑制抖动的效果与离散趋近律的设计参数及系统的采样时间有着密切的关系。为此,在分析指数趋近律抖动的基础上,提出了一种自适应滑模控制器,Mat LAB能够进一步的提高基于趋近律的滑模控制器的抖动抑制能力。为了验证本文所提出方法的有效性,在Mat LAB中实现了该算法,并利用其来控制采摘机器人关节的伺服电机。仿真结果表明:本文所提的算法具有较好的位置跟踪能力,进一步地抑制了指数趋近律滑模控制中存在的抖动现象,提高了系统的性能。 相似文献