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Guohai Xia and Lailiang Cheng

One-year-old `Concord' grapevines (Vitis labruscana Bailey) were fertigated with 0, 5, 10, 15, or 20 mm N in a modified Hoagland's solution for 8 weeks during summer. Half of the vines fertigated at each N concentration were sprayed with 3% foliar urea twice in late September while the rest served as controls. Four vines from each treatment combination were destructively sampled during dormancy to determine the levels and forms of N and carbohydrates. Nitrogen fertigation during the summer did not significantly alter vine N concentration whereas foliar urea application in the fall significantly increased vine N concentration. In response to foliar urea application, concentrations of both free amino acid-N and protein-N increased, but the ratio of protein-N to free amino acid-N decreased. Arginine was the most abundant amino acid in free amino acids and proteins, and its concentration was linearly correlated with vine N concentration. Concentrations of total nonstructural carbohydrates (TNC) decreased slightly in response to N supply from fertigation. Foliar urea application in the fall significantly decreased TNC concentration at each N fertigation level. Starch, glucose, and fructose decreased in response to foliar urea applications, but sucrose concentration remained unaffected. Approximately 60% of the carbon decrease in TNC caused by foliar urea application was recovered in proteins and free amino acids. We conclude that free amino acids account for a larger proportion of the N in vines sprayed with foliar urea compared with the unsprayed vines, but proteins remain as the main form of N storage. In response to foliar urea application, part of the carbon from TNC is incorporated into proteins and free amino acids, leading to a decrease in the carbon stored in TNC and an increase in the carbon stored in proteins and free amino acids.

Open access

Syuan-You Lin and Shinsuke Agehara

foliar application of urea, LS, or ZS can be an important adaptation tool for subtropical blackberry production. These defoliants have several key features for successful commercial implementation. First, they are all readily available chemicals: ZS and

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C. Yang, D.Y. Jiao, Z.Q. Cai, H.D. Gong, and G.Y. Li

manipulate the physiology of plants by application of PGRs as observed in some annual and perennial oilseed crops ( Abdelgadir et al., 2010 ; Day, 2000 ; Ghosh et al., 1991 ; Prat et al., 2008 ). However, to date the regulation mechanism of PGRs of P

Open access

Derek J. Plotkowski and John A. Cline

., 2017 ; Gutiérrez-Gamboa et al., 2018 ; Meng et al., 2018 ). Hannam et al. (2016 ) conducted an N-fertilization experiment based on grapes, which demonstrated that the application of foliar N was most effective for increasing YAN in grapes when the

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T.K. Hartz, K.S. Mayberry, M.E. McGiffen, M. LeStrange, G. Miyao, and A. Baameur

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A.M.S. Nyomora, P.H. Brown, K. Pinney, and V.S. Polito

The effect of boron (B) on in vivo and in vitro development of almond [Prunus dulcis (Mill.) D.A. Webb (syn. P. amygdalus Batsch)] pollen and pollen tubes and the resultant effect on fruit set was studied in mature trees. The cultivars Mono (pistil donor) and Butte (pollinizer) in an orchard with low soil B in Fresno, California were sprayed with B at 0, 0.8, 1.7, or 2.5 kg·ha-1 during Fall 1993. Pollen viability as indicated by the fluorescein diacetate method (FDA) was >85% and was not affected by field-applied B, however, in vivo pollen germination and tube growth were enhanced by foliar-applied B. More effect of applied B on in vivo growth appeared as pollen tubes progressed toward the ovary. For in vitro germination, foliar-applied B reduced bursting of tubes, and addition of B to the culture media significantly increased pollen germination and pollen tube growth.

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F. Chéour, C. Willemot, J. Arul, Y. Desjardins, J. Makhlouf, P.M. Charest, and A. Gosselin

Effects of CaCl2 preharvest treatment on postharvest strawberry (Fragaria × ananassa) ripening and gray mold development were assessed. Two experiments were carried out in 1987 on two sites. In the first experiment, the effects of rate of application of CaCl2 and degree of fruit maturity at treatment were studied with the conventional cultivar Kent. In the second experiment, the influence of concentration and frequency of application of CaCl2 was investigated with day-neutral `Tribute'. Calcium treatment caused a significant increase in fruit and leaf Ca contents, which were closely correlated. The degree of fruit maturity at application and the frequency of treatment did not affect Ca concentration in the tissues. Several maturity criteria were measured during fruit storage in air at 4C. Anthocyanin and free-sugar contents and tissue electrical conductivity increased, while titratable acidity and firmness decreased. In both experiments, Ca treatment delayed ripening and gray mold development. The delay increased with increasing Ca concentration.

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Fahed A. Al-Mana and Tajelsir I.M. Idris

Foliar spray of either BA or GA3 alone or in combinations of the two growth regulators were tested for their effects on Bryophyllum plants. Neither BA nor GA3 alone succeeded in stimulating lateral branching or flowering. GA3 totally inhibited bulbils formation. In a panel evaluating the ornamental quality, plants treated with GA3 at 100 ppm ranked top. The combination of BA and GA3 enhanced growth, branching, flowering and bulbils formation. The combinations of BA and GA3 at 50 ppm each, significantly improved the propagative qualities of the bulbils. Chemical names used: N-(phenylmethyl) -H purin-6-amine (BA), Giberllic acid (GA3).

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Brian E. Whipker and Shravan Dasoju

Plant growth retardant (PGR) foliar spray treatments (mg•liter–1) of daminozide at 1000 to 16,000; paclobutrazol from 5 to 80; and uniconazole from 2 to 32 were applied to `Pacino' pot sunflowers (Helianthus annuus) to compare their effectiveness at chemical height control. When the first inflorescence opened, the number of days from seeding until flowering, total plant height measured from the pot rim to the top of the inflorescence, inflorescence diameter, and plant diameter were recorded. Total plant height, plant diameter, inflorescence diameter, and days until flowering were significant for the PGR treatment interaction. Marketable-sized plants grown in the 1.2-liter pots were produced with uniconazole concentrations between 16 and 32 mg•liter–1 or with daminozide concentrations between 4000 and 8000 mg•liter–1. Paclobutrazol foliar sprays up to 80 mg•liter–1 had little effect and higher concentrations or medium drench treatments should be considered.

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Jorge B. Retamales and Cerardo A. Accedondo

Calcium gradients were established in firm (`Bluecrop' and `Blueray') and soft (`Ivanhoe') highbush blueberry (Vaccinium corymbosum L.) fruits from a 7-year-old planting at La Union, southern Chile. Manual firmness measurements established that `Ivanhoe' fruit was softer than either `Bluecrop' or `Blueray'. In all varieties, Ca concentrations were: seed > pulp > epidermis; opposite trends were found for K+Mg/Ca ratios. Seed number and Ca concentration in the pulp were negatively correlated in `Bluecrop' and `Ivanhoe', but not in `Blueray'. In a related experiment, the response of `Bluecrop' to preharvest sprays of two calcium sources (chloride and nitrate) in four doses (0, 47.5, 35, or 190 g Ca/100 liters of water) was studied; dose and source interactions were not significant. Both calcium sources affected fruit Ca concentrations similarly;l calcium applications, either as nitrate or chloride, increased Ca significantly in epidermis and seed; the highest dose was required to raise significantly Ca concentrations in the pulp. K+Mg/Ca ratios in nitrate- or chloride-treated fruit were: pulp > seed > epidermis.