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Lawrence R. Parsons, T. Adair Wheaton, and William S. Castle

Conversion of wastewater to reclaimed water for crop irrigation conserves water and is an effective way to handle a growing urban problem: the disposal of wastewater. Water Conserv II is a large reclaimed water project developed by Orlando and Orange County, Fla., that presently irrigates ≈1900 ha of citrus. The project includes a research component to evaluate the response of citrus to irrigation using reclaimed water. Citrus trees in an experimental planting responded well to very high application rates of reclaimed water. Irrigation treatments included annual applications of 400 mm of well water, and 400, 1250, and 2500 mm of reclaimed water. The 2500-mm rate is excessive, and since disposal was of interest, this rate was used to determine if citrus could tolerate such high rates of irrigation. The effects of these treatments were compared on `Hamlin' orange [Citrus sinensis (L.) Osb.] and `Orlando' tangelo (C. paradisi Macf. × C. reticulata Blanco) combined with four rootstocks: Carrizo citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.], Cleopatra mandarin (C. reticulata Blanco), sour orange (C. aurantium L.), and Swingle citrumelo (C. paradisi × P. trifoliata). Growth and fruit production were greatest at the highest irrigation rate. Concentration of soluble solids in the juice was usually lowered by the highest irrigation rate, but total soluble solids per hectare were 15.5% higher compared to the 400-mm rate, due to the greater fruit production. While fruit soluble solids were usually lowered by higher irrigation, the reduction in fruit soluble solids observed on three of the rootstocks did not occur in trees on Carrizo citrange. Fruit peel color score was lower but juice color score was higher at the highest irrigation rate. Crop efficiency (fruit production per unit of canopy volume) was usually lower at the 2500-mm rate and declined as trees grew older. Weed cover increased with increasing irrigation rate, but was controllable. Irrigation with high rates of reclaimed water provided a satisfactory disposal method for treated effluent, benefited growth and production of citrus, and eliminated the need for other sources of irrigation water. Reclaimed water, once believed to be a disposal problem in Florida, is now considered to be one way to meet irrigation demands.

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Zimian Niu, Dapeng Zhang, Jicheng Zhan, and Curt Rom

Influence of photosynthetically active radiation (PAR) microclimate in the canopy of four training systems [open-center with high trunk (OH); open-center with middle trunk (OM); open-center with low trunk (OL); and a traditional round canopy (RC)] on the growth, yield and fruit quality of apple were studied in the Beijing area. The results showed that: 1) the growth and yield potential were affected by canopy light microclimate. The average leaf chlorophyll content from OH, OM and OL systems was 12.3% to 18.1% greater than that from the RC system. Trees from OH, OM, and OL systems produced 84.2% to 89.7% of shoot forming flower clusters compared to only 47.3% to 50.9% of the RC shoots. Training system did not affect total yield of 8-year-old trees, but in 10-year-old trees the RC system had lower yields compared with open-center systems. 2) Fruit quality was also affected by canopy light microclimate. The average anthocyanin content in the skin of fruit from OH, OM, and OL systems was 35.9% to 46.1% higher than that from the RC system, but chlorophyll content from the OL system was higher than in the open-center systems. Meanwhile, the contents of TSS and esters in apple flesh from the open-center systems were significantly higher than that from the RC system. 3) When the relative value of PAR in canopy exceeded 33.8%, the growth index of trees (chlorophyll: return-bloom ratio) exceeded 66.6% and the fruit quality index (TSS × anthocyanin) exceeded 94.7%. When PAR was less than 20.6%, the growth index was under 37.2% and the fruit quality index was under 67.5%. PAR value was significantly correlated with the growth and fruit quality index in the four training systems, and the total canopy volume of higher PAR(exceeding 33.8%, relative value) from OH, OM, and OL systems was 37.1% to 45.0% greater than that from the RC system.

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W.A. Erb, A.D. Draper, and H. J. Swartz

Abbreviations: A, apparent net photosynthesis; Berryland, Berryland sand soil high in organic matter; CYV, canopy volume; DMP, dry-matter production; E, transpiration; g L , leaf conductance of water; Galestown, Galestown sandy clay loam soil; IC

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Kelly T. Morgan, T.A. Obreza, and J.M.S. Scholberg

planted intermittently during the previous 20 years, resulting in trees of widely ranging canopy volume. The trees had been fertilized with dry soluble fertilizer three or more times per year and were irrigated with wellwater using a low

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Alisson P. Kovaleski, Jeffrey G. Williamson, Bruno Casamali, and Rebecca L. Darnell

increased lateral shoot number and length compared with late pruning ( Bañados et al., 2009 ). Williamson and Darnell (1996) reported that regrowth and canopy volume of ‘Sharpblue’ SHB was greater when plants were pruned early after harvest compared with

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Peter C. Andersen and Brent V. Brodbeck

r 2 . Yield/m 2 canopy area was calculated in 2010, 2012, and 2014 as yield/tree cross-sectional area. Tree canopy volume was calculated using the equation for one half of an oblate spheroid (4/6 π r 2 h ) where r is the average tree cross

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Wendy L. Wilber and Jeffrey G. Williamson

fertilizer rate (fertilizer analyses combined) are reported for each cultivar independently. For leaf nutrient content, the effects of fertilizer analysis and rate are shown for each cultivar. Vegetative growth. Canopy volume for both cultivars

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Luis Rallo, Diego Barranco, Raúl de la Rosa, and Lorenzo León

consequence, the vigor of ‘Chiquitita’ in terms of canopy volume remained ≈60% to 70% of ‘Arbequina’ across years ( Table 2 ). ‘Chiquitita’ showed a compact and weeping habit of growth with dense canopy and branches trending downward with crop so that canopy

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Godfrey P. Miles, Ed Stover, Chandrika Ramadugu, Manjunath L. Keremane, and Richard F. Lee

commercial planting of Citrus . To maintain high ACP pressure and maximize challenge by C Las, no insecticides were applied, and high ACP populations were apparent year round. Growth measurements. Tree height, canopy width, tree canopy volume (TCV), trunk

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François Mademba-Sy, Zacharie Lemerre-Desprez, and Stéphane Lebegin

line (D line ); 2) canopy diameter perpendicular to the planting line (D perp ); 3) trunk diameter at 10 cm above the level of the graft; 4) trunk diameter at 10 cm below the level of the graft; and 5) tree height (H). Canopy volume was calculated using