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Holly L. Scoggins-Mantero and Harry A. Mills

`Freedom' poinsettias (Euphorbia pulcherrima Willd. ex Kl.) were grown to flowering in solution culture for 11 weeks. Treatments consisted of five ammonium: nitrate nitrogen ratios: 1:0, 3:1, 1:1, 1:3, and 0:1 with a total N concentration of 150 mg N/liter. The balance of essential nutrients was supplied with a modified Hoagland's solution. Fresh weight, dry weight, and macro- and micronutrient content of bracts, leaves, petioles, stems, and roots were determined at the end of the study. Leaf and bract area also was measured. Maximum bract size was achieved with 100% nitrate (0:1) treatment. Leaves were largest with the 1:3 ratio. Plants receiving ammonium as the sole N source exhibited severe ammonium toxicity symptoms: stunted growth, foliar chlorosis and necrosis, premature leaf abscission, stunted and clubby roots, and delayed or nonexistent bract coloring. Dry weights for bracts, leaves, stems, and roots increased as the ratio of nitrate increased. Elemental uptake was monitored weekly. Nitrogen-form effect on the uptake, concentration, and partitioning of other nutrients also was evaluated.

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Y. Suenaga, K. Takamori, F. Nishimot, S. Miyoshi, and T. Higashi

It is not uncommon that tipburns, deformation, and poor coloring of strawberries, delaying of differentiation of flowering buds and flowering, etc., occur reflecting rapid changes in soil solution concentrations by repeated applications of conventional fertilizers. These physiological disorders contribute to lowering the yield and quality of strawberries to a significant extent. Polyolefin coated urea called “MEISTER” is one of the excellent controlled availability fertilizers whose dissolution is primarily controlled by temperature. Therefore, blended materials of a few MEISTER products can supply N matching the plant demand for the long growing season (8 months). This results in contributing to the prevention of occurrences of the physiological disorders described above. Treatment plots using blended materials of MEISTER products were early dissolution, even dissolution, and late dissolution and were fertilized with a single basal application. Compared with the conventional plot, the late dissolution plot was most suitable for strawberry growth, producing the largest yield of high quality. The new fertilization using MEISTER will contribute to decreasing the amount of fertilizer to apply, eliminating topdressing, saving labor cost, etc.

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Robert P. Rice Jr., Shelly Baird, and Linzy Gatlin

Greenhouse Whitefly (Trialeurodes vaporariorum) and Silverleaf Whitefly (Bemisia argentifolii) are the most serious insect pests of poinsettia. Most growers rely on the use of foliar insecticide applications before bract coloring and an application of a single soil application of imidicloprid (Marathon) subsequently. This research was undertaken to investigate the use of reflective mulches or bench covers, which have been shown to be effective in outdoor applications for control of whitefly in the greenhouse. In an early trial, silver painted pot spacers and silver polyethylene mulch were placed between pots and both nymphs on leaves and adults caught on yellow sticky cards were monitored. Nymph populations were reduced by ≈35% and adults caught on sticky cards increased by ≈40% when compared with the control. In a subsequent trial, reflective bench covers were combined with the use of yellow sticky tape placed above the canopy of the crop and compared with sticky tape alone, reflective mulch alone, and no treatment. The combination of sticky tape and reflective mulch significantly reduced whitefly populations after 6 weeks and performed better than either of the other treatments alone.

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Eric A. Curry

Within red cultivars, highly colored apples are often preferred. In addition to being esthetically more appealing. better color often indicates riper, better tasting fruit. Anthocyanin synthesis in apples is influenced by many external factors including light, temperature, nutrition, pruning, thinning, growth regulators, and bagging. Bagging is the practice of enclosing young fruitlets in several layers of paper to promote color development after the bag is removed in the fall before harvest. In experiments related to the temperature optimum of color development in various cultivars, bagging was used to produce fruit void of anthocyanins. Double layer paper bags (black-lined outer bag, red inner bag) were placed on `Akafu-1 Fuji', `Oregon-Spur Delicious', and the early coloring `Scarlet Spur Delicious' on June 21, 1993. Bags were not removed until fruit was taken to the lab on September 22 for both `Delicious' and `Fuji'. Whereas bagged `Fuji' apples were without red pigment, bagged `Delicious' sports showed considerable red pigment development, completely covering the apple in the case of the blush-type `Scarlet Spur' and showing streaks without pigment in the snipe-type `Oregon-Spur'.

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Zlatko Cmelik and Stanislav Tojnko

Canopies of `Fuji' apple trees, grafted on M.9 rootstock, planted in 1998 on two orchard sites at 2.8 × 0.7 m and trained as super spindles, were subdivided in Spring 2003 into upper and lower parts. In each part, the number of fruits, yield per tree, external (fruit size classes, and fruit coloring), and internal (total sugar content, titratable acid content, and flesh firmness) fruit quality attributes were determined. The orchard site parameters affected growth, yield, and fruit quality in different ways. The less suitable orchard site had less growth, lower yield per tree, and a lower percentage of first class fruits, but most fruits had good color (86% in top and 75% in lower part of canopy). The favorable orchard site produced higher growth and yield, and a higher percentage of first class fruits, but fruits had poorer color. In the lower part of the canopy, fruits were of a good size, but had poor color. Fruits of the best quality were obtained from the top part of the tree.

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Satoru Kondo, Wanvisa Ponrod, Sirichai Kanlayanarat, and Nobuhiro Hirai

Endogenous abscisic acid (ABA), its 2-trans isomer (trans-ABA), phaseic acid (PA), and dihydrophaseic acid (DPA) concentrations were quantified in the peel, aril, and seed of mangosteen (Garcinia mangostana L.). Changes in carbon dioxide (CO2) and ethylene (C2H4) production and 1-aminocyclopropane-1-carboxylic acid (ACC) concentration in the peel and aril were also examined. ACC concentration and CO2 and C2H4 production were high at the beginning of fruit development and gradually decreased toward harvest, which confirms that mangosteen is a nonclimacteric fruit. In the peel and aril, the increase in ABA concentration preceded the decrease in peel firmness and coloring of the peel. This suggests that ABA may induce the maturation of mangosteens. The state of ABA metabolism varied with the part of fruit. In the peel, PA and DPA were not considered to be predominant metabolites of ABA because their concentrations were low compared to ABA throughout fruit development. In contrast, in the aril and seed, it is possible that the PA-DPA pathway may be a main pathway of ABA metabolism because the concentrations of DPA in the aril and of PA in the seed directly coincided with the concentrations of ABA. The differences in the ABA metabolites between aril and seed may be caused by the rate of ABA metabolism. The concentrations of ABA and its metabolite in the seed decreased toward harvest.

Open access

Huihui Zhang, Ping Yu, Min Song, Dalu Li, Qianqian Sheng, Fuliang Cao, and Zunling Zhu

Ginkgo biloba, a relict plant, has been popularized and planted in most areas of China for its leaves, timber, and fruits. In the present study, the dynamic changes in leaf color, leaf pigment content during the color change period, and photosynthetic characteristics in different growth periods were studied to explore the coloring mechanism and adaptability of five late-deciduous superior Beijing G. biloba cultivars (LD1–LD5). The results showed that the leaf color change of each superior cultivar was relatively stable, and the discoloration period of LD3 and LD5 was later than that of others. From September to November, the chlorophyll a, chlorophyll b, and total chlorophyll content in all superior cultivars showed a downward trend, except in LD3, in which the pigment content was slightly higher in October than in September. Except in LD3 and LD4, the ratio of carotene content to total chlorophyll content in other cultivars slightly decreased in October. In May, the photosynthetic capacity of LD5 was stronger than that of other cultivars. The photosynthetic capacity of LD3 was strong in July and October. Our results imply that LD3 and LD5 are suitable for mixed planting with common G. biloba to increase the overall leaf color viewing period. Ginkgo biloba leaves turn yellow in autumn because of both a decrease in the chlorophyll content after leaf senescence and an increase in the Car content during leaf senescence. Although LD5 presented rapid seedling emergence, LD3 grew faster during the vigorous and late growth stages and is thus suitable for agricultural production.

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Ebrahiem Babiker, Stephen J. Stringer, Hamidou F. Sakhanokho, John J. Adamczyk Jr., and Arlen D. Draper

Horticultural Laboratory for homeowners and nursery industry. ‘Muffin Man’ is characterized by notable fall coloring in leaves and numerous unique pale pink blooms that arise on long reproductive shoots, where berries develop with attractive color ranging from

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Pei Xu, Tingting Hu, Yuejian Yang, Xiaohua Wu, Baogen Wang, Yonghua Liu, Dehui Qin, Jeffrey Ehlers, Timothy Close, Zhongfu Lu, and Guojing Li

red are found in both subspecies. The inheritance mode of cowpea flower coloring is genotype-dependent. A monogenic inheritance with complete dominance ( Padi, 2003 ; Sangwan and Lodhi, 1998 ), an interaction of two genes in a complementary manner and

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Donald N. Maynard

uses such as a windbreaks and medicinal preparations of many sorts. Finally, the spices turmeric ( Curcuma longa L.) and long coriander ( Eryngium foetidum L.) are included in the last section of the book. Turmeric rhizomes are used as a coloring