Vincent Russo

Kenaf extract affects germination and post-germination development of weed, grass and vegetable seeds

Metabolites produced by one organism can affect development of other organisms. Kenaf (Hibiscus cannabinus L.) is used in products which put it in direct contact with other plants. This project was designed to determine whether kenaf plant extracts can affect germination and development of vegetable, grass and weed seeds. Frost-killed kenaf was chipped and either immediately frozen (weathered 0 months) or applied to the soil in mats in December and allowed to weather for 2 or 4 months. Kenaf samples, weathered from 0 to 4 months, were ground and soluble materials were extracted with distilled water. Seeds of cucumber (Cucumis sativus L.), green bean (Phaseolus vulgaris L.), tomato (Lycopersicon esculentum Mill.), redroot pigweed (Amaranthus retroflexus L.) and annual Italian ryegrass (Lolium multiflorum Lam.) were exposed to 0, 16.7, 33.3, and 66.7 g/l of kenaf extract. Distilled water and three concentrations of polyethylene glycol (PEG) were included as controls. After 7 days, total germination and hypocotyl and radicle lengths were determined. Extracts of kenaf weathered up to 4 months, especially at the highest concentration, reduced germination in pigweed by 50–70%. Germination in tomato and ryegrass was reduced by 30% when exposed to the highest concentration of unweathered kenaf. As length of time of weathering of kenaf increased, germination and length of most plants increased. This suggests that, over time, the detrimental compounds in kenaf were leached or otherwise changed so that they had no effect or became beneficial. Non-weathered kenaf or its extracts, may be employed to suppress weeds. Alternatively, weathered kenaf tissue or extracts may stimulate germination and post-germination development of existing economic crops.

Cultural Methods and Mineral Content of Eggplant (Solanum melongena) Fruit

Mineral content in edible portions of vegetables may be affected by cultural methods. This study was conducted to determine if fertiliser rate and irrigation regime affected mineral (N, NO 2 , NO 3 , P, PO 4 , K, SO 4 , Ca, Fe, Na, Mg, and Mn) of eggplant (Solanum melongena L, cv Black Bell) fruit. The experiment on a Bernow fine-loamy, siliceous, thermic Glossic Paleudalf soil at Lane (OK, USA) with three fertiliser rates and three irrigation regimes. The data were analysed as a split-plot with harvests as the sub-plot. All P was accounted for by PO 4 . Levels of NO 2 and NO 3 comprised <0.001% of the N content. Harvest number affected only N, P, K, SO 4 and Mg levels in both years, and Na in one year. For many of the minerals the highest levels in fruit were not consistent over harvests in both years. When there was less precipitation, and fertiliser was applied at the recommended rate, fewer irrigations per week were necessary to increase levels of N, P and K in fruit. The interaction of irrigation and fertiliser can affect mineral content of fruit and should be considered when fertiliser recommendations are made.