| Abstract: | Tainan District Agricultural Improvement Station began in February 1991 to evaluate the feasibility of using degradable plastic films for horticultural crops production. Products from China, Korea, Israel, Germany, U.S.A. and Taiwan were used for comparison. Results are summarized as follows: Macro-and micro-environmental changes in different seasons affected the degradation time of the tested degradable plastic films. The silver/black bio/photo-degradable PE films containing 20% starch from USI Far East Corporation degraded after 56, 83, 38, and 33 days when they were mulched in fall(October, 1991), winter(December, 1991), spring(April, 1992) and summer (August, 1992), respectively. The more starch incorporated, the faster the films degraded. No difference was observed in size, weight, yield, total soluble solids and heavy metal contents of the fruits of cantaloupe and watermelon grown on the beds mulched with various kinds of degradable PE films or traditional PE film. No difference was observed in yield as well as the heavy metal (Fe, Pb, Ni, Cu, Cd and Cr) contents in the edible part of the crops of cabbage mustard and head lettuce that were grown in the soil without or incorporated with debris of degradable PE films in 6 consecutive years. The same results were also obtained in another trial on cantaloupe and paddy rice for 4 consecutive years. Various amounts(0, 4, 8, 16, 32 and 64g) of used degradable PE films were seperately mixed with field soil. The mixed soil were used to grow paddy rice in clay pots. No difference was observed in plant height, length and weight of the spike, 1,000-seed weight and the kernel per spike among the treatments at harvesting. Six pieces (each 10cm□10cm) of Bioplastics, Bioflex and Green choice biodegradable films were buried in a 8-inch clay pot. Then head lettuce were planted in the pots. No difference was observed in head weight and qualities(vitamin C. total soluble solids and crude fiber)either among the treatments or the control. The weight losses for Bioflex, Bioplastics and Green choice were 58.4%,47.9% and 11.3%, respectively after 40 days. |
