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  • Author or Editor: Brent K. Harbaugh x
  • Journal of the American Society for Horticultural Science x
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The ornamental value of caladium (Caladium ×hortulanum Birdsey) depends primarily on leaf characteristics, including leaf shape and main vein color. Caladium leaf shapes are closely associated with plant growth habit, stress tolerance, and tuber yield; leaf main vein colors are often used for cultivar identification. Thirty-eight crosses were made among 10 cultivars and two breeding lines; their progeny were analyzed to understand the inheritance of leaf shape and main vein color and to determine if there is a genetic linkage between these two traits. Results showed that a single locus with three alleles determined the main vein color in caladium. The locus was designated as V, with alleles V r, V w, and V g for red, white, and green main veins, respectively. The white vein allele was dominant over the green vein allele, but it was recessive to the red vein allele, which was dominant over both white and green vein alleles; thus the dominance order of the alleles is V r > V w > V g. Segregation data indicated that four major red-veined cultivars were heterozygous with the genotype Vr V g, and that one white-veined cultivar was homozygous and one other white-veined cultivar and one breeding line were heterozygous. The observed segregation data confirmed that the three leaf shapes in caladium were controlled by two co-dominant alleles at one locus, designated as F and f, for fancy and strap leaves, respectively. The skewedness of leaf shape segregation in some of the crosses implied the existence of other factors that might contribute to the formation of leaf shape. Contingency chi-square tests for independence revealed that caladium leaf shape and main vein color were inherited independently. The chi-square tests for goodness-of-fit indicated that the five observed segregation patterns for leaf shape and main vein color fit well to the expected ratio assuming that two co-dominant and three dominant/recessive alleles control leaf shape and main vein color and they are inherited independently.

Free access

Abstract

Nicotine sulfate and resmethrin, applied at recommended rates, were less toxic to adults and larvae of Encarsia formosa than were endosulfan, malathion, or naled. Adult parasites were killed by contact with any of the 5 chemicals. Endosulfan and malathion left residues toxic to adult E. formosa for 2 to 3 weeks; malathion and naled killed many 10- to 15-day-old parasite larvae. The potential uses of nicotine sulfate and resmethrin were shown in theoretical models for integrated control of greenhouse whitefly.

Open Access

Abstract

Eight lacewing (Chrysopa earned) larvae per greenhouse snapdragon (Antirrhinum majus), released 4 at a time twice during 8 weeks effectively controlled aphids (Myzus persicae). Two initial sprays of malathion and nicotine sulfate 1 week apart followed by release of 4 lacewing larvae per plant also were effective. Flowers produced under chemical or biological control systems were equal in quality. Lacewing larvae in a 21°C greenhouse required a week longer to effectively control aphids than those in a 24°C greenhouse.

Open Access

Abstract

Gypsophila paniculata L. cv. Bristol Fairy flowered only under long photoperiods. Neither 5°C storage up to 8 weeks nor weekly GA3 sprays at concentration from 50 to 2,000 mg/liter induced flowering at short photoperiods. Established shoots with 12 nodes flowered after 3 weeks of 24 hours photoperiod induction, but young shoots with 5 nodes (newly pinched plants) did not flower after 3 weeks of induction. Critical photoperiod of several selections of ‘Bristol Fairy’ ranged from 12-18 hours. Inadvertent selection of clones with longer critical photoperiods appears to be responsible for poor winter flowering in Florida.

Open Access