| Summary: | 碩士 === 國立臺灣大學 === 園藝暨景觀學系 === 107 === In this study, lettuce (Lactuca sativa ‘Fu San’) and corn (Zea mays ''Hua Chen'') were used as materials for regulated deficit irrigation (RDI) and chitin and chitosan was added under regulated irrigation, evaluated for their effects on plant growth and water-saving benefits.
In the lettuce RDI experiment, the lettuce was divided into two phases, 7-12 leaves were in the early stage, and 12-18 leaves were in the late stage, with mild and moderate water deficit. In the corn RDI experiment, the corn was divided into vegetative stage and reproductive stage with water deficit. In addition, in the lettuce and corn supplemented experiment, lettuce and corn were supplemented with 2000 mg·L-1 chitin, 200 mg·L-1 and 400 mg·L-1 medicinal chitosan and commercial chitosan (JinJiaZan) under water deficit.
The results showed that the yield of the mild and moderate water deficit treatment in the early stage of lettuce in summer was not reduced compared with the control group, and the yield water-use efficiency (WUEyield) and the biomass water-use efficiency (WUEbiomass) could be improved, thus saving 2.63% and 21.05% of the irrigation water. There was no significant difference in the treatment of lettuce in the winter. In the later stage, the moderate water deficit WUEyield and WUEbiomass, which could saved 28.63% of the irrigation water. There was no significant difference in growth between the control and the RDI treatment of corn, but reproductive stage water deficit were the highest WUEyield and WUEbiomass, which could save 40.10% of irrigation water, followed by the vegetative stage water deficit, which can save 22.70% of irrigation water.
The results of the experiment of addition chitin and chitosan indicated (medicinal chitosan and commercial chitosan) under water deficit that lettuce was added with 200 mg·L-1 and 400 mg·L-1 medicinal chitosan and JinJiaZan in the treatment of fresh weight and WUEyield was no significant difference in the RDI treatment, but there was a better trend in the treatment of 200 mg·L-1 chitosan and Jinjiazan. The RDI addition of 200 mg·L-1 chitosan treatment of dry weight, plant height, root length, leaf number, leaf area and WUEbiomass were better trend then the treatment of RDI addition 2000 mg·L-1 chitin and RDI addition of 200 mg·L-1 JinJiaZan. Fresh weight, dry weight and plant height of corn were not significantly different between the treatment of RDI addition 200 mg·L-1 and 400 mg·L-1 chitosan and JinJiaZan treatment, but consider the economic efficiency RDI addition 200 mg·L-1 treatment is better. After that, the fresh weight, dry weight and plant height of corn treated with RDI addition 2000 mg·L-1 chitin and RDI addition 200 mg·L-1 chitosan and JinJiaZan were no significant differences in growth statistics.
Although the lettuce was used to adjust the water use efficiency in the summer to improve the water use efficiency of crops compared with winter. There was no significant difference in the winter lettuce and corn RDI treatment test, indicating that the sensitivity of lettuce to water deficit in winter decreased, which in turn could save more water, and it was also speculated that corn was more resistant to drought. In the future, we can try to increase the water deficit intensity to save more water and achieve precision agriculture. Although the results of this test showed that chitin or chitosan lettuce and corn did not have significant by water saving effect on lettuce and corn, but the taste is better, it is speculated that chitin or chitosan may increase the total soluble solids of lettuce and corn, so it needs further exploration.
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