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Michael V. Mickelbart

( Snyder and Struve, 1997 ). The goal of this study was to determine the differences in leaf characteristics and nutrient concentrations resulting from position (north, south, east, and west directions) and age (early-season versus late-season leaves

Free access

M.E. Garcia, R.C. Rom, J.B. Murphy, and G.W. Felton

The foliar phenolic content of 21 apple cultivars was evaluated. Ten leaves were sampled randomly from three positions on current-season terminal shoots. Shoots were divided as tip, middle, and basal positions. The phenolic content was determined by spectrophotometric method (390 nm) using diphenylboric acid 2-aminoethyl ester as the reagent and caffeic acid as standard. Cultivars varied significantly in phenolic content. `Stark Ultra Red' had the highest amount, and `Liberty' had the lowest amount. Significant variations in the phenolic content due to leaf position were observed. Phenolic content was highest in leaves from the tip position, and it decreased toward the basal portion of the shoot. Factors affecting the phenolic content of apple cultivars will be investigated to determine apple × insect interactions.

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I. Okutani and N. Sugiyama

A negative relationship has been reported between the oxalate concentration in leaves and leaf position numbered from the base for `Okame' spinach (Spinacia oleracea L.). We compared changes in leaf and stem oxalate concentrations among three cultivars. `Viroflay' differentiated and developed leaves at a lower rate than did `Okame' and `Kyoho'. Oxalate concentrations in plant tops decreased with time in `Okame' and `Kyoho', but `Viroflay' changed little. The relationship between leaf oxalate concentration (Y; millimoles per gram of fresh weight) and its position on the stem (X) was the same for all cultivars and can be given as Y = -0.0089X + 0.158.

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Sang Gyu Lee* and Chiwon W. Lee

The relationship between source leaf position and the photo-assimilate translocation and distribution was characterized for tomato (Lycopersicon esculentum Mill.) grown in the greenhouse. Three different positions of source leaf on the stem (first node above or below the first fruit cluster and fifth node above the first fruit cluster) were tested for their influence on 14CO2 assimilation and transfer to different parts of the plant. The leaves at the fifth node above the first fruit cluster transferred the highest (57%) proportion of C14 to other plant parts, followed by leaves borne on the first node below the first fruit cluster (50%), and the first node above the first fruit cluster (39%). In all treatments, fruits served as the strongest sink for C14, followed by stem, leaf, and root tissues. The leaf borne on the fifth node above the first fruit cluster transferred the largest amount of C14 to the second fruit cluster.

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Enrique E. Sanchez and Timothy L. Righetti

Abbreviations: HN, high N; LN, low N; NFF, N derived from fertilizer; SLW, specific leaf weight. 1 INTA Alto Vane, CC 782, 8332 General Rota, Argentina. 2 Associate Professor. Oregon Agricultural Experiment Station Paper no. 8993. Part of a thesis

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Sanliang Gu, Susanne Howard, and Martin K. Walsh

The effects of shoot positioning, leaf removal, cluster shading, and curtain orientation on fruit composition and primary bud cold hardiness were investigated in mature `Norton/Cynthiana' grapevines (Vitis aestivalis) trained to Geneva double curtain (GDC) trellis system. For four years (1995–1998) juice soluble solids content, total titratable acidity, and pH were not affected shoot positioning. Cluster shading, curtain orientation, and leaf removal affected fruit composition at harvest. Fruit from the south-facing curtain of the GDC trellis system had higher juice soluble solid content, pH, and skin pigmentation than fruit from the north-facing curtain. Cluster shading decreased skin pigmentation while cluster shading at the highest level only (95%) increased pH and decreased total titratable acidity. Leaf removal, which increases light exposure of the fruit, increased juice pH in the 1997 experiment only. Juice potassium level was decreased by shoot positioning, but not cluster shading or curtain orientation. Cold hardiness of primary buds was affected by these treatments early in the winter, but the differences in primary bud cold hardiness among the treatments diminished toward the end of the dormant season.

Open access

Xiaotao Ding, Liyao Yu, Yuping Jiang, Shaojun Yang, Lizhong He, Qiang Zhou, Jizhu Yu, and Danfeng Huang

Adalsteinsson, 2006 ; Lu et al., 2012 ; Matsuda et al., 2014 ). Leaf area and other growth indices at different leaf positions have been studied in tomato by Chang et al. (2011) and in purple yam by Hgaza et al. (2009) , but the leaf growth and

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Bruce L. Dunn and Carla Goad

the position of chlorophyll sensor readings (tip, blade, base) on a leaf, if leaf N concentration varies according to leaf sampling method, and determine the best sampling technique for correlating leaf N concentration to contact optical sensor

Open access

Noa K. Lincoln, Theodore Radovich, Kahealani Acosta, Eli Isele, and Alyssa Cho

growth is generally slow and neither flowers nor fruit have yet developed. Three branches from each of the four cardinal directions were selected from each tree. One leaf was collected from the first four leaf positions (leaf position one = first fully

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Vania Lanari, Oriana Silvestroni, Alberto Palliotti, Alan Green, and Paolo Sabbatini

Not much is known about the influence of leaf position on photosynthesis in water-stressed leaves. We do know that stomatal control of water loss is an early plant response to water deficit under field conditions ( Chaves, 1991 ; Cornic and