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Abstract
Seeds of hairy indigo, a tropical legume cover crop, are dormant due to hard seed coats. Immersion of the seed in concentrated H2SO4 for 20 or 30 minutes or hot water at 70° to 80°C for 2 minutes, significantly increased the germination percentage and rate. H2SO4 was more effective than hot water. Redrying the seed after treatment improved the effectiveness of the treatments slightly.
A three year study involving solar heating of soil (soil solarization) with clear polyethylene mulch demonstrated for two years, control of root-knot nematodes (Meloidogyne incognita). The population of M. incognita was reduced >90% in the 0-30cm depth of solarized soil. The number of eggs per gram root recovered and the root gall index from `Georgia-Jet' sweetpotatoes were reduced (92-98%) by soil solarization. Growth and yield were enhanced in solarized soil. The beneficial effects of solarization was observed in the second year following two additional cropping cycles of collard greens and sweetpotatoes.
Flowers emit volatile compounds that attract pollinators. In ornamental plant breeding programs, fragrance is a significant character that adds value to flowers for its consumer appeal. In Hawaii, anthurium (Araceae) is an important crop used for cut flowers and flowering potted plants. Unlike other ornamentals, fragrance is not presently associated with commercial anthuriums. However, several anthurium species are known to have distinctive scents. To obtain the novelty trait of fragrance in anthurium, an understanding of anthurium scent genetics, physiology, and chemistry is required. Scented anthurium species and hybrids in the Univ. of Hawaii germplasm collection have been studied. Fragrance emission among species varies with time of day—some species being scented only in the morning, only at night, or all day long. Fragrance emission also varies with stage of spadix development, with some species having scent as pistillate and/or staminate flowers. The species sampled comprise five categories: A. amnicola, A. formosum, and A. lindenianum are minty; A. armeniense is sweet; A. gracile is floral; A. bicollectivum, A. cerrobaulense, A. folsomii, and A. harleyii are fruity; and A. supianum is fishy. Some of the chemical components are illustrated.
Partial steam and chemical sterilization of soil rich in organic matter increased the soil nutrients, little information exists with regard to the effect of soil solarization (SS) in this regard. A study was established to determine the effects of SS in combination with wheat residue and subsequent crop residue on increased growth response (IGR) of cole crops and soil fertility for two years. SS for 90 days increased K+, P, Ca++ and Mg++ 3 times more within five months after SS. The SS effect released higher levels of total N in the soil. However, increase levels of N was lower than that required for maximum IGR of collard. The IGR of cole crops without fertilizers was higher in SS plots as compared to bare soil. The IGR of collard was evident almost two years after SS.
The volatile compounds in soursop (Annona muricata L.) were obtained by a liquid-liquid continuous extraction procedure from the aqueous solution of blended soursop pulp and analyzed by gas chromatography (GC) and GC-mass spectrometry (MS). Twelve volatiles were identified by comparing their mass spectra and Kovats retention indexes with those of standard compounds: five were identified tentatively from MS data only, eight are being reported for the first time. (Z) -3-hexen-l-ol was the main volatile present in mature-green fruit, while methyl (E) -2-hexenoate, methyl (E) -2-butenoate, methyl butanoate, and methyl hexanoate were the four main volatiles present in ripe fruit. Concentrations of these five volatiles decreased and several other unidentified volatiles appeared when the fruit became overripe.
Field plots on Norfolk sandy loam soil at Tuskegee and Eufaula, AL were treated by soil solarization (SS). Samples rhizsosphere (R) and nonrhizosphere soil from cole crop and strawberry plots were collected and assayed with selective media for population densities of microbes involved in organic decomposition and mineralization. Microflora population densities of bacteria, actinomycetes and fungi increased 2-7 folds in the solarized compared to the bare soil (BS). Microflora population densities in the soils involved in cellulose and protein decomposition, ammonification, nitrification, phosphate mineralization were greater in solarized soil compared to BS. Nitrogen-fixing bacteria in R soil 7 months after SS was higher when compared to BS at Tuskegee, but was reduced 50 folds 18 months after SS.