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Effects of calcium nitrate Levels and Soaking Durations on Cocopeat Nutrient Content

Journal of Agricultural Chemistry and Environment 2021年第3期10卷 372-388页

作者： Sheku N. Gbollie Samuel M. Mwonga Anthony M. Kibe Department of Crops Horticulture and Soils Faculty of Agriculture Egerton University Njoro Kenya

Cocopeat, a by-product of the coconut (Cocos nucifera L.), is an important soilless media that contains high potassium (K), sodium (Na), and electrical conductivity (EC) depending on its source. Methods for extracting these elements and thus lowering EC are yet to be standardized. This study was therefore carried out to investigate two extraction methods of these elements in cocopeat. A greenhouse pot experiment was carried out at the Climate and Water Smart Agriculture Centre of Egerton University, Kenya. It was laid out in a 5 × 4 factorial completely randomized design. Five soaking durations (12, 24, 36, 48, and 72 hours) and four calcium nitrate (Ca(NO3)2) levels (0, 60, 100, and 150 g) were used. The experiment was done in two folds: the leachate and treated cocopeat examination for their chemical properties. The General Linear Model procedures were used for Analysis of Variance at (P ≤ 0.05). The results showed that the addition of Ca(NO3)2 100 g extracted significantly more K and Na in the leachate than Ca(NO3)2 0.0 g and 60 g. The EC levels in the leachate increased with the application levels of Ca(NO3)2 while the pH levels were reducing. In the treated cocopeat, Ca(NO3)2 100 g and soaking duration 36 hours significantly reduced K and Na and sufficiently supplemented Ca and N. Irrespective of Ca(NO3)2 and soaking durations, after the cocopeat is washed, the EC and pH values fall within their suitable ranges. There was a strong negative correlation between Ca and Na, Ca and K, and between Na and EC. Also, strong positive correlation between Ca and N and Ca and EC. Effective supplementation of Ca and N, and optimal reduction of K and Na by 78.44% and 92%, respectively can be achieved with 100 g of Ca(NO3)2 1.5 kg-1 of cocopeat in 15 liters of water with a soaking duration of 36 hours.

关键词： calcium nitrate Cocopeat Leachate Potassium Soaking

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Comparison of Antioxidant Activity and Antioxidant Components in Lettuce, Onion and Tomato Obtained with Different Levels and Forms of Nitrogen Fertilization

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Journal of Agricultural Science and Technology(A) 2014年第7期4卷 597-604页

作者： Ragab Abdelmohsen E1-Mergawi Khalid Naser Al-Redhaiman Hussein F. Abouziena Department of Plant Production and Protection College of Agriculture and Veterinary Medicine Qassim University Buraidah51452 Al-Qassim Saudi Arabia Department of Botany Agricultural & Biological Research Division National Research Center Cairo 12622 Egypt

The effect of N levels and sources on the antioxidant components in vegetable is not completely understood. Therefore, greenhouse experiments were conducted to determine the changes in antioxidant capacity diphenyl-2-picrylhydrazyl （DPPH） and ferric reducing antioxidant power （FRAP）, total phenolics, ascorbic acid, total carotene and lycopene contents in edible portions of lettuce, onion and tomato due to different nitrogen levels and sources. The experiment included three N levels （20, 40 and 60 kg/ha for lettuce trial and 60, 120 and 180 kg/ha for either onion or tomato） and four nitrogen sources （calcium nitrate, ammonium sulphate, ammonium nitrate and urea）. The antioxidant capacity and phenolic contents in lettuce was enhanced under low nitrogen level, while the antioxidant capacities, phenolics, carotenoids and lycopene in tomato fruits were not significantly affected by the nitrogen dose applied. Application of calcium nitrate caused 50% increase in DPPH and 20% in FRAP of lettuce compared to other nitrogen forms. Tomato treated with calcium nitrate or ammonium sulphate had higher phenolic and ascorbic acid contents than treated plants with ammonium nitrate or urea. Antioxidant tested parameters of onion were not significantly affected by the nitrogen treatments. Nitrogen concentration in tomato fruits significantly correlated with FRAP antioxidant capacity, phenolics, ascorbic acid, carotene and lycopene contents.

关键词： Ammonium nitrate ammonium sulphate ascorbic acid calcium nitrate carotene phenolics urea.

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