Yield increase and disease suppression of sweet corn (Zea mays var. Bonanza) by the application of chitosan-based biostimulant

Corn, an important crop in Indonesia still has a low productivity, thus many efforts are required to fulfill its national demand. One of the solutions to improve corn yield is by applying biostimulant containing chitosan as an active ingredient. Chitosan has been proved to increase plant growth and resistance against diseases. The objective of this research was to study the effects of several chitosan formulas on the yield and diseases occurance in sweet corn (Zea mays var. Bonanza). The chitosan formulas tested were soluble liquid (SL), wettable powder (WP), nano chitosan (NN), and unformulated chitosan (CH). The experiment was arranged using a randomized block design with three replications. All chitosan formulas were applied by seeds soaking for 20 minutes, followed by foliar spraying on corn plants at three weeks after planting (WAP), with the concentration of 500 ppm (400 L/ha spray volume), every three weeks until 9 WAP. Parameters observed were brix value, weight of corn cobs, weight of corn biomass, and plant diseases including downy leaves, leaf blight and leaf rust. The results showed that NN formula increased the brix value up to 7%, the corn cob weight up to 49% and the biomass weight up to 34% compared to the control; whereas SL formula reduced the incidence of downy mildew by 53% at 3 WAP and leaf blight disease by 51% at 6 WAP. In addition, the incidence of corn leaf rust reduced 59-71% in corn plant subjected to all chitosan formulas. Based on the results, application of chitosan in NN formula was best in increasing yield, while in SL formula was best in reducing the incidence of important corn diseases.