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D.L. Peterson, S.S. Miller, and J.D. Whitney

Three years of mechanical harvesting (shake and catch) trials with two freestanding apple (Malus domestica Borkh.) cultivars on a semidwarf rootstock (M.7a) and two training systems (central leader and open center) yielded 64% to 77% overall harvesting efficiency. Mechanically harvested `Bisbee Delicious' apples averaged 70% Extra Fancy and 10% Fancy grade, while two `Golden Delicious' strains (`Smoothee' and `Frazier Goldspur') averaged 40% Extra Fancy and 13% Fancy grade fruit. Mechanically harvesting fresh-market-quality apples from semidwarf freestanding trees was difficult and its potential limited. Cumulative yield of open-center trees was less than that of central-leader trees during the 3 years (sixth through eighth leaf) of our study. `Golden Delicious' trees generally produced higher yields than `Delicious' trees.

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R.C. Beeson Jr. and G.W. Knox

Volume of water captured in a container as a function of sprinkler type, spacing, plant type, and container size was measured for marketable-sized plants. Percent water captured was calculated and a model to predict this value derived. Percent water captured was inversely related to the leaf area contained in the cylinder over the container when containers were separated, and with total plant leaf area at a pot-to-pot spacing. This relationship was independent of leaf curvature (concave vs. convex). Canopy densities were less related to percent water captured than leaf areas. Irrigation application efficiencies separated by spacing ranged from 37% at a close spacing to 25% at a spacing of 7.6 cm between containers. Container spacing, canopy shedding, and possibly some canopy retention of water later lost by evaporation were determined to be the main factors associated with the low efficiencies. The results suggest that higher irrigation application efficiencies would be maintained only if plants were transplanted to larger containers before reaching maximum canopy size rather than spacing existing containers to achieve more room for canopy growth.

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Zhongchun Jiang, W. Michael Sullivan, and Richard J. Hull

Efficient utilization of fertilizer-nitrogen (N) by turfgrasses is probably related to N uptake efficiency of roots and metabolic efficiency of absorbed N in roots and shoots. This study evaluated Kentucky bluegrass (Poa pratensis L.) cultivars for potential differences in nitrate uptake rate (NUR), temporal variation in NUR, and the relationship between NUR and N use efficiency (NUE), defined as grams dry matter per gram N. Six cultivars were propagated from tillers of seeded plants, grown in silica sand, mowed weekly, and watered daily with a complete nutrient solution containing 1.0 mm nitrate. A nutrient depletion method from an initial nitrate concentration of 0.5 mm was used to determine NUR of 5-month-old plants. NUR (μmol·h-1 per plant) of the six cultivars ranked as follows: `Blacksburg' > `Conni' > `Dawn' > `Eclipse' = `Barzan' > `Gnome'. When NUR was based on root weight, `Conni' ranked highest; when NUR was based on root length, surface, or volume, `Eclipse' ranked highest. Averaged across cultivars, NUR on the second day was greater than NUR for the first day of nitrate exposure. Temporal variation was greatest in `Blacksburg', while none was noted in `Conni' or `Eclipse'. Cultivar differences in NUE were significant in fibrous roots, rhizomes, and leaf sheaths, but not in leaf blades and thatch. Total nitrate uptake was positively related to total N recovered and total plant dry matter, but NUR based on root weight was negatively correlated with NUE of the whole plant.

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T.M. DeJong, W. Tsuji, J.F. Doyle, and Y.L. Grossman

A clingstone peach (Prunus persica L. Batsch `Ross' on `Nemaguard' rootstock) orchard was established at the Univ. of California Kearney Agricultural Center, Parlier, for evaluating the economic efficiency of three high-density planting systems in comparison with the conventional Open Vase system. The orchard contained four replicate plots (0.80 ha/plot), each containing four different planting systems. The four planting/training systems (in-row spacing given first) were: the “KAC-V” (a perpendicular V system spaced 2.0 × 5.5 m, 919 trees/ha); the “HiD KAC V” (spaced 1.8 × 4.6 m, 1196 trees/ha); the “Cordon” (spaced 2.4 × 4.0 m, with perpendicular harvest drives 4.8 m every 22 m and tree height limited to 2.5 m, 919 trees/ha); and the “Open Vase” (spaced 6.1 × 5.5 m, 299 trees/ha). All system-specific costs and crop yields were recorded annually on each subplot for the first 5 years. Although the Cordon system had the highest yields in the second year, the V systems had the highest returns after 5 years. Cumulative costs were: HiD KAC-V system > KAC-V ≥ Cordon > Open Vase. The system that was designed to maintain tree height <2.5 m (Cordon) tended to be less profitable than the V systems because of modest crop yields and high pruning costs that were not offset by increased harvest efficiency. In the last 3 years of the study, pruning, thinning, and harvesting accounted for the majority of the system-specific costs.

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Zhongjie Ji, James J. Camberato, Cankui Zhang, and Yiwei Jiang

photosynthetic efficiency, and increased oxidative injury ( Parihar et al., 2015 ). Plants can adjust metabolism to cope with salinity stress. This includes, but is not limited to, accumulation of water-soluble sugars and organic acids for osmotic adjustment

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Shahrokh Khanizadeh, Yvon Groleau, Odile Carisse, Vicky Toussaint, Raymond Granger, and Gilles Rousselle

efficiency and precocity compared with ‘M.26’ and ‘M.9’ in sandy loam soil ( Khanizadeh et al., 2005 ). ‘SJM150’ produces very low or no suckers compared with ‘M.9’ and the same amount of burr knots compared with ‘M.9’ and ‘M.26’. ‘SJM150’ was among the 56

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Shahrokh Khanizadeh, Yvon Groleau, Odile Carisse, Vicky Toussaint, Raymond Granger, and Gilles Rousselle

freedom from root suckers compared with ‘M.9’ ( Table 1 ), superior hardiness ( Khanizadeh et al., 2000 ), ease of propagation, and better yield efficiency ( Table 2 ). Table 1. Burr knots, sucker number, trunk cross-sectional area (TCSA), height

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Allen V. Barker

Enhancing the Efficiency of Nitrogen Utilization in Plants . Sham S. Goyal, Rudolph Tischner, and Amarjit Basra, editors. 2005. Food Products Press, 10 Alice Street, Binghampton, NY 13904-1580. 489 p. incl. index. $59.95, softback. ISBN-13: 978

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Shahrokh Khanizadeh, Yvon Groleau, Odile Carisse, Vicky Toussaint, Raymond Granger, and Gilles Rousselle

-Food Canada (AAFC) Research Station, St-Jean-sur-Richelieu, Quebec. It produces dwarf trees smaller than ‘M.26’ but larger than ‘Malling 9’ (M.9). It was released because of its superior hardiness and similar cropping efficiency compared with ‘M.26’ and less

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Shahrokh Khanizadeh, Yvon Groleau, Odile Carisse, Vicky Toussaint, Raymond Granger, and Gilles Rousselle

dwarf trees equal to ‘Ottawa 3’ (O.3) but with better precocity (early fruiting), higher yield efficiency (based on yield/trunk cross-sectional area), lower suckers, and wider branch angles. ‘O3A’ is similar to ‘O.3’ in susceptibility to two races of