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Sunghee Guak, Lailiang Cheng, Leslie H. Fuchigami, and Sunghee Guak

Bench-grafted `Fuji'/M.26 trees were sprayed with 1% CuEDTA on 31 Oct., defoliated manually on 12 Nov., or allowed to defoliate naturally. Foliar urea at 3% was applied at 14 days and 9 days before CuEDTA treatment. Plants were harvested after natural leaf fall and stored at 2 °C. One set of the plants were destructively sampled for reserve N (expressed as total Kjeldahl N or soluble protein concentration) analysis, and the remaining plants were transplanted into a N-free medium in the spring without any N supply for 40 days after budbreak. CuEDTA resulted in >80% defoliation within 5 days of application. Trees defoliated with CuEDTA had lower reserve N content than naturally defoliated controls, but had higher N than hand-defoliated controls. Foliar urea application before the CuEDTA treatment significantly increased reserve N level in all tree parts, without affecting the efficacy of CuEDTA on defoliation. The extent of spring regrowth was proportional to the reserve N level of the tree. Urea-treated plants, whether hand- or CuEDTA defoliated, had more growth in the spring than hand- or naturally defoliated controls. It is concluded that CuEDTA, as combined with foliar urea, can be used to effectively defoliate apple nursery trees, and increase reserve N level and improve regrowth performance during establishment.

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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.

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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.

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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.

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

This investigation was carried out during the experimental seasons of 1991–92 and 1992–93 on 25-year-old `Washington' navel orange trees grown in an orchard at Beni Suef (≈120 km south of Cairo). This part of the investigation studied the effect of foliar spraying 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) on some vegetative aspects and leaf content of some macro- and micronutrients. The investigation also included the effect of number and date of spraying (one spray 3 weeks before flowering, one spray 4 weeks after fruit set, and two sprays at the two dates) on the studied traits. The results showed that the overall treatments included two sprays of urea, micronutrients (Zn, Mn, Fe, and Cu) and NAA at 10 ppm achieved the highest values for average leaf area and shoot diameter in both seasons. The treatment on shoot length was more effective when GA3 replaced NAA. Leaf analysis showed that the application of any of the nutrients was responsible for a pronounced increase in leaf content of that element, but reduced the contents of others. Growth regulator treatments lowered leaf content of the determined elements. However, all other treatments in this study reduced leaf content of P and K.

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J.L. Walworth, D.E. Carling, and G.J. Michaelson

Head lettuce (Lactuca sativa L.) cv. Salinas was produced in field trials in southcentral Alaska with varying planting dates, planting methods, N sources, and N application rates. Variables measured included head weight and diameter and harvest date. Nitrogen source had little effect on head weight. Direct-seeded lettuce produced heaviest beads from early plantings; transplants produced heaviest heads when planted in mid- to late season. Transplanting generally produced heavier heads than direct-seeding. Head weight of transplanted and direct-seeded lettuce was maximized with ≈112 kg N/ha. The data suggest that 112 kg N/ha may be suitable for lettuce direct-seeded or transplanted throughout the growing season.

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Y. Teraoka, K. Kubo, S. Miyoshi, and T. Higashi

A capillary watering system can easily control water supply to cyclamen and can save nutrient losses by leaching. Introduction of single basal placement using MEISTER will be useful to innovate the traditional cyclamen culture. The conventional cyclamen culture using Nutricote needs double transplanting and double fertilization. In the new cyclamen culture, cyclamen seedlings (sowed on the plug tray in early January) were transplanted to 15-cm pots fertilized with MEISTER in early June. The selected MEISTER was one belonging to the sigmoid dissolution group, which showed delayed release during summer and the maximum release in early September. The new fertilization supplied N to the plants until the end of growing season. The growth of cyclamen plants on two experimental plots were compared at the flowering stage. Numbers and weight of flowers per pot and bulb weight were greater in the new culture than in the conventional culture though the total volume of leaves was less in the former. Regarding the nutrient absorption, the plants of the new culture showed lower concentrations of N and P in the leaves but higher concentrations of Ca and Mg compared to those in the conventional culture. Such nutrient uptake could contribute to preventing the occurrence of tipburn in the new culture.

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K. Takamori, T. Ishida, S. Miyoshi, K. Ayama, and T. Higashi

A hundred days and 240 days are required for growing strawberry plants in the nursery and in the greenhouse, respectively. Therefore, fertilization using conventional fertilizers is often repeated. To eliminate repeated topdressing, to decrease the amount of N to apply, and to save farming labor, a new fertilization method using MEISTER was studied. Since MEISTER is an excellent controlled fertilizer, the new method can apply all N necessary to grow strawberry plants almost for a year only by a single application (no N fertilizer is applied to the greenhouse soil). The experimental plots basically consist of two kinds of treatment: changing ratios of soil volume per pot or per plant (50 to 800 ml/pot) and kinds and levels of fertilizers (conventional fertilizer and two kinds of MEISTER). The experimental results showed 1) soil of ≥200 ml/pot is necessary to grow strawberry seedlings in summer when the soil is subjected to drying, 2) a blended material of two MEISTER products with sigmoid dissolution can supply N for the whole growing season, and 3) MEISTER application can reduce 40% of the total N conventionally applied.

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Mongi Zekri and Robert C.J. Koo

Abbreviations: MU, methylene urea; SCK, sulfur-coated potassium; SCU, sulfur-coated urea. Florida Agricultural Experiment Station Journal Series no. R-01551. The cost of publishing this paper was defrayed in part by the payment of page charges

Open access

Isaac T. Mertz, Nick E. Christians, and Adam W. Thoms

establishment, aid recovery, and enable grasses to better withstand environmental stresses ( Aamlid et al., 2017 ; Jones and Christians, 2011 ; Mertz, 2015 ; Mertz et al., 2017 ; Zhang et al., 2013 ). Furthermore, the industry standard urea N must be