ABSTRACT
Chitosan was prepared from shrimp shell (alpha chitosan) and from squid pen (beta chitosan) with degree of deacetylation of about 70%. Degradation of chitosan in flake form by combined treatment with H2O2 and gamma Co-60 radiation was carried out. Results showed that combined treatment was highly effective for degradation of chitosan to obtain low molecular weight of 1-2 105. Oligochitosan was prepared by irradiation of chitosan solution of 50g/l (5%, w/v).
The dose required for oligochitosan with water soluble content of more than 70% was of 32kGy and 48kGy for alpha and beta chitosan, respectively. Synergic effect of degradation of chitosan in solution with 1% H2O2 and gamma Co-60 radiation was also investigated. The dose to obtain oligochitosan was reduced from 32kGy to 4kGy for beta and 48kGy to 8kGy for alpha chitosan.The elicitation and growth promotion effect of oligochiotsan for sugarcane and rice were investigated. Results showed that oligochitosan with water soluble content of 70-80% (Mw~6,000-12,000) exhibited the most effective elicitation and growth promotion for plant. The optimum oligochitosan concentration by spraying was of 30 and 15ppm for sugarcane and rice, respectively. The disease index of Ustilgo scitaminea and Collectotrichum falcatum on sugarcane were reduced to 44.5 and 72.3% compared to control (100%). The productivity of sugarcane was increased about 13% (8tons/ha). The disease index of Pyricularia grisea on rice was reduced to 53.0% for leaf and 34.1% for neck of bloom compared to control (100%). The productivity of rice was increased for 11-26% (0.6-1.4 tons/ha).
The obtained results indicated that oligochitosan is promising to use as a biotic elicitor for plant particularly for sugarcane and rice. The procedure for production of oligochitosan elicitor by irradiation method was set up and the economic benefit by using oligochitosan elicitor for sugarcane and rice was preliminarily estimated.
(Nguyen Quoc Hien1, Truong Thi Hanh1, Vo Thi Kim Lang1,
Dang Van Phu1, Doan Thi The1, Bui Phuoc Phuc2, Cao Anh Duong3
1Research and Development Center for Radiation Technology, Vietnam Atomic Energy Commission
2College of Natural Sciences, National University Ho Chi Minh City, Vietnam
3Research and Development Center for Sugarcane, Vietna)
Dang Van Phu1, Doan Thi The1, Bui Phuoc Phuc2, Cao Anh Duong3
1Research and Development Center for Radiation Technology, Vietnam Atomic Energy Commission
2College of Natural Sciences, National University Ho Chi Minh City, Vietnam
3Research and Development Center for Sugarcane, Vietna)
