Research on impact of chitosan oligomers on biophysical characteristics, growth, development and drought resistance of coffee

Effects of chitosan and chitosan oligomer solutions on biophysical characteristics, growth, development and drought resistance of coffee have been investigated. The experiments which involved spraying chitosan and chitosan oligomer onto the leaves of coffee were conducted in a greenhouse and in the field. The concentration of chitosan and chitosan oligomer solution used was 0, 20, 40, 60 and 80 ppm. Obtained results showed that chitosan oligomer enhanced strongly the content of chlorophylls and carotenoid in the leaves of coffee seedlings up to 46.38–73.51% compared to the greenhouse control. Application of chitosan oligomers also increased mineral uptake of coffee and stimulated the growth of coffee seedlings. Spraying chitosan oligomers with concentration of 60 ppm increased the height of the coffee seedlings up to 33.51%, in the stem diameter up to 30.77% and the leaf in area by up to 60.53%. In addition application of chitosan oligomers reduced by 9.5–25.1% transpiration of the leaves at 60 and 120 min. Therefore the application of chitosan oligomer could be a good way of increasing the drought resistance of coffee seedlings.Application of chitosan oligomer in field conditions increased content of total chlorophylls up to 15.36% compared to the control. Application of chitosan oligomers also enhanced mineral uptake of coffee by 9.49% N; 11.76% P; 0.98% K; 18.75% Mg; 3.77% Ca and decreased 15.25% the rate of fallen fruits compared to the control, contributed to increasing yield and developing sustainable production of coffee in Vietnam.