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Gang Li and Michael R. Evans

Seedlings of Cucumis sativus (cucumber), Tagetes patula (marigold), Viola tricolor (pansy), Pelargonium × hortorum (geranium), and Impatiens wallerana (impatiens) were germinated on towels soaked with either deionized water, nutrient control solutions, or humic acid solutions. Root fresh weight and root dry weights were higher for all seedlings germinated on towels soaked with humic acid as compared to seedlings germinated on towels soaked with deionized water or nutrient control solutions. Lateral root number and total lateral root length were higher for cucumber, marigold, pansy, and geranium seedlings germinated on towels soaked with humic acid than those germinated on towels soaked with deionized water or nutrient control solutions. Root fresh and dry weights were higher for impatiens, Begonia semperflorens (begonia), marigold, and geranium seedlings germinated in a sphagnum peat: vermiculite (80:20, %v/v) substrate drenched with humic acid as compared to seedlings germinated in substrate drenched with deionized water or nutrient control solutions. Foliar sprays of humic acid also resulted in increased root fresh and dry weights while foliar application of nutrient control solutions either had no effect or reduced root fresh and dry weights.

Open access

Samutumwa Liyembani and Bradley H. Taylor

Abstract

A single or four sequential foliar sprays of paclobutrazol (PBZ) and XE-1019 (Valent Corp., Walnut Creek, Calif.) to peach [Prunus persica (L.) Batsch.] supplied, respectively, 7.5 to 480 mg a.i. and 0.75 to 48 mg a.i. doses per tree. These treatments reduced the net change in total shoot length (current-season extension shoots plus lateral shoots) occurring over the 15-week period after the sprays were applied by up to 80% and 69%, compared to the control, for each compound, respectively. The average number of lateral shoots was decreased 85% and 81% by the highest dose of each material. The shoot and whole plant dry weight at the end of the growing season (15 weeks after treatment) were ≍22% and 27% lower than the control for PBZ and XE-1019, respectively. Trunk cross-sectional area, leaf area, and dry weight of leaves and roots were also smaller on the trees treated by either compound. Root : shoot ratios were not influenced by any treatment. Chemical names used: β-[(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazole-1-ethanol (paclobutrazol); (E)-1-(p-chlorophenyl)-4-,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol (Valent XE-1019).

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Guihong Bi and Carolyn F. Scagel

, 1995 ; Tagliavini et al., 1999 ). Foliar fertilization in fall is an alternative to supplying N to the soil. In some perennial plant species, foliar sprays of urea after terminal bud set can improve N storage without stimulating new growth or delaying

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Yuqi Li and Neil S. Mattson

al., 2009 ; Spann and Little, 2011 ). The objective of this study was to determine effects of RWE on plant growth and drought tolerance of tomato and petunia transplants when applied as a drench or foliar spray at various concentrations. Materials

Open access

Mingxia Wen, Peng Wang, Weiqin Gao, Shaohui Wu, and Bei Huang

improve the concentration of soluble sugar, vitamin C, soluble protein, and soluble solid solution but reduce the concentration of organic acids, thereby improving the quality of table grapes. According to a study by Zhao et al. (2013 ), foliar spraying

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Youzhi Chen, John M. Smagula, Walter Litten, and Scott Dunham

In a managed field of native Vaccinium angustifolium Ait. clones, the effect of fall foliar sprays of B at 345 g·ha-1 and/or Ca at 3,450 g·ha-1 in remedying tissue deficiency of B varied among 12 clones, as seen in pollen germinability and on individual stems as seen in flower number, fruit set, and number of harvestable berries. With Ca applied alone, increased berry size did not overcome yield reduction due to fewer flowers and berries per stem. Berry diameter and mass correlated better to number of seeds of germinable size than to total number of seeds. Pollen germination averaged 17.4% on stigmata from untreated clones, and all three treatments (B, Ca, B + Ca) increased that average by 8%. More seeds per berry with the B-alone treatment implies more ovules fertilized when B deficiency is remedied. No relation was found between in vitro and in vivo pollen germination.

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Ahmed M. Akl, Abdel-Fattah M. Eid, and Mohamed Y. Hegab

This investigation studied the effects of foliar sprays of urea (0.5%), a mixture of Zn (0.4%), Mn (0.3%), Fe (0.5%), and Cu (0.3%) in sulfates from 23% Zn, 28% Mn, 19% Fe, and 30% Cu, respectively, and two growth regulators (GA3 at 25 ppm and α-NAA at 10 ppm), as well as number and date of sprays, on the number of fruit/tree, average fruit weight, and yield/tree in kilograms. Spraying `Washington' navel orange trees with urea and/or micronutrients significantly increased the number of fruit/tree, average fruit weight, and yield/tree expressed in kilograms. However, the treatment including both of them was the most effective in 1991–92 and 1992–93. Application of GA3 and NAA effectively increased the value of the three traits compared with the control; however, spraying the trees with NAA was responsible for higher fruit numbers, while GA3 was more effective in increasing fruit weight. Two sprays of urea, micronutrients, and NAA (or GA3), the first applied 3 weeks before flowering and the second 4 weeks after fruit set, were more effective than spraying once at any of the two dates in producing high numbers of fruit/tree, average fruit weight and yield per tree by weight.

Open access

D. R. Leece and J. F. Dirou

Abstract

The ability of urea foliar sprays containing hydrocarbon or silicone surfactants to maintain leaf N concentration in mature prune (Prunus domestica L.) trees was tested in a non-irrigated commercial orchard near Young, New South Wales. In 1976-77, foliar-applied N was as effective in maintaining leaf N concentration as soil-applied N on a g for g N basis, but a silicone surfactant which enabled sprays to completely wet leaves and to spontaneously penetrate open stomata, was no more effective in terms of leaf N concentration than a conventional hydrocarbon surfactant. In 1977-78, a drought year, foliar-applied N was more effective than soil-applied N. However, the silicone surfactant was less effective than the hydrocarbon, as run-off was excessive and the spray film dried very rapidly. Inclusion of the humectant glycerol in the silicone sprays retarded the rate of drying and eliminated the difference between the surfactants. A combination of soil and foliar N is suggested as a means of maximizing control of tree N status in most years. However, conventional surfactants appear to be slightly superior to silicone surfactants in high-volume spraying.

Free access

Ahmed M. Akl, Abdel-Fattah M. Eid, and Mohamed Y. Hegab

This part of the investigation studied the effect of foliar spraying with urea (0.5%); a mixture of Zn (0.4%), Mn (0.3%), Fe (0.5%), and Cu (0.3%) in sulphates (from 23% Zn, 28% Mn, 19% Fe, and 30% Cu, respectively); and two growth regulators (GA3 at 25 ppm and α-NAA at 10 ppm); as well as number and date of sprays on fruit volume, percentage of pulp, juice acidity, TSS, reducing and total sugars, TSS: acid ratio, and vitamin C content. The results showed that Washington Navel orange trees receiving urea, micronutrients, or both gave fruit with significantly larger volume compared with the control, but the treatment including both resulted in the highest values for fruit volume in 1991–92 and 1992–93 seasons. GA3 sprays gave the highest fruit volume, followed by NAA, while the water spray (control) gave the lowest values for this trait. Two sprays of urea, micronutrients, and GA3 resulted in the highest fruit volume in 1991–92 and 1992–93 seasons. The effect of different treatments on pulp percentage were slight and mostly insignificant in the two experimental seasons. Spraying urea, micronutrients, or both slightly reduced juice acidity and increased TSS, sugars, and vitamin C contents, as well as TSS: acid ratio; however, both of them together was more effective in this respect. Conversely, either GA3 or NAA caused an appreciable increase in acid content in the juice, but decreased the other determined constituents, except vitamin C, which increased.

Free access

Ahmed M. Akl, Abdel-Fattah M. Eid, and Mohamed Y. Hegab

This part of the investigation studied the effect of foliar spraying with urea (0.5%); a mixture of Zn (0.4%), Mn (0.3%), Fe (0.5%), and Cu (0.3%) in sulphates (from 23% Zn, 28% Mn, 19% Fe, and 30% Cu, respectively); and two growth regulators (GA3 at 25 ppm and α-NAA at 10 ppm); as well as number and date of sprays on fruit pedicel pectin content, some flowering aspects, and fruit set and drop percentages. Applying urea, micronutrients, or both significantly increased pectin content in the pedicels of the attached and dropped fruit. The treatment including urea plus micronutrients resulted in the highest values for pectin in fruit stem. Either GA3 or NAA significantly raised pectin content over that of the water-sprayed control. However, NAA was more effective in increasing pectin content in fruit pedicel. The overall treatment including urea and micronutrients with GA3 or NAA was the most effective in producing the highest percentage of leafy inflorescence in 1991–92 and 1992–93 seasons. Any nutrition treatment was significantly effective in increasing fruit set and reducing fruit drop compared with the water-sprayed control; however, the treatment including all sprayed nutrients was the most effective. Application of GA3 or NAA significantly increased fruit set percentage and reduced June and preharvest fruit drop; however, NAA was more effective in reducing fruit drop than GA3.