Foliar Application of Micronutrients and Low Molecular Weight Polysaccharides on White Radish Grown in Impoverished Soil

Abstract

Foliar application has been considered as the most effective way to supplement nutrients for crops. Besides macro- and micro-nutrients, foliar fertilizers should contain surfactants to wet plant leaves, and other adjuvants to control spray and prolong the retention time of nutrients on the leaf surface. Having diverse structures and properties, some polysaccharides can not only be used as drift control or adhesion agents to improve performance on the leaf and reduce washout of agrochemicals by rainwater, but also be utilized as plant growth promoters (PGP) or immuno-stimulating agents in agricultural production. In this study, low molecular weight chitosan and xanthan obtained by radiation degradation have been added to the microelement fertilizers to control diseases, promote the growth and development of vegetables, and further increase their nutrient uptake. Field trials on white radishes grown on impoverished soil revealed that the resulting foliar fertilizers significantly reduced the infection of popular pests and diseases, remarkably promoted the growth and development of the radish plants. The yield attributes and marketable yield of radish from all treatments were much higher than those of the control. The highest yields were 61.99 and 64.94 tons per ha in season 2019 and 2020, respectively, in the plants treated with the fertilizer containing both chitosan and xanthan. These results suggest that the fertilizer composed of micronutrients and low molecular weight chitosan and xanthan could be applied for better vegetable crops.