Effect of Plastic Mulch Color on Growth of Leaf Lettuce (Lactuca sativa L.) and Pak-choi (Brassica campestris L.)
| Autor: | Le Thi Huong Van, 黎香云 |
|---|---|
| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 Effects of plastic mulch color on root temperature, photosynthetic photon flux density (PPFD) reflection and growth of leaf lettuce (Lactuca sativa L.) cv. ‘No. 3’ and pak-choi (Brassica campestris L.) cv. 'Feng Jing' and cv. 'Brisk Green' were investigated in greenhouse at different climates in three croppings of plants transplanted in September, 2003, November, 2003 and January, 2004. Five plastic mulches including aluminum polyethylene, clear plastic, green plastic, red plastic, and yellow plastic were compared to the nonmulch control. The significant difference in PPFD between control and mulched treatments was shown in Sept. crop but not in Nov. and Jan. crops. The PPFD tended to increase on mulch surfaces, except red plastic, during three croppings. The highest PPFD were measured on aluminum polyethylene and yellow plastic which were 6-21% higher than in control. Root temperature under mulches was higher than in control during three croppings. The highest root temperature was shown under aluminum polyethylene and clear plastic which was 2.6 to 3.1oC higher than the control at midday. Green, red and yellow plastics had similar effect on root temperature. Plant growth and yield as well as physiology parameters of leaf lettuce and pak-choi were affected by color mulching. The effect of mulch varied during croppings. Yields decreased in mulched treatments compared to control by 17-28% in Sept. crop but increased in clear and yellow plastics by 27-71% in Nov. and Jan. crops except pak-choi cv. 'Feng Jing' in Nov. crop which was not influenced by the color mulching. Aluminum polyethylene enhanced root growth in Nov. and Jan. crops but did not affect plant fresh weight and yield. Aluminum polyethylene increased chlorophyll contents of leaf lettuce and pak-choi cv. 'Brisk Green' grown in Sept. crop but not in Nov. and Jan. crops. Although the significant difference was not constant, the highest chlorophyll contents were shown in green plastic and the lowest contents was in red and yellow plastics. Photosynthetic rate of the three crops decreased in aluminum polyethylene and clear plastic by 15-40% or 18-43%, respectively, as compared to control in Sept. crop but it responded less to color mulching in Nov. and Jan. crops. Yellow plastic increased carbohydrate levels in leaves and roots of plants grown in Nov. and Jan. crops while aluminum polyethylene increased carbohydrate level in roots. The lowest nitrate content in leaves of the three crops were shown in control and yellow plastic in Sept. or Jan. crop, respectively. In Nov. crop, nitrate content in leaves of pak-choi cv. 'Feng Jing' grown in green plastic was higher than in yellow plastic but there were no differences among treatments in leaf lettuce and pak-choi cv. 'Brisk Green'. Percentage of pak-choi leaves injured by diamond-back moth (Putella xylostella L.) generally decreased in mulched treatments during the three crops, however, yellow plastic was the most efficient mulch to reduce the leaf injury. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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