Foliar application of cyanobacterial formulations stimulates plant growth and fruit quality in tomato under protected cultivation

Abstract

ABSTRACT Cyanobacterial biofertilizers enhance plant and soil productivity across crops, through soil-seed application at the field level; however, their use as foliar treatment is less investigated. This study evaluated the role of foliar sprays, initiated 4 weeks after transplantation of nursery-raised seedlings in beds, and effected at weekly intervals for a period of eight weeks. towards enhancing plant growth, yield and quality of tomato grown in a climate-controlled polyhouse. Sprays were composed of aqueous formulations of carrier alone, and those amended with the formulations of plant-growth-promoting cyanobacterium Anabaena laxa (A. laxa) or biofilm Anabaena torulosa -Trichoderma viride (An-Tr) or suspension of 100 µM Fe EDTA. A. laxa brought about a significant increase in nitrate reductase and glutamine synthetase activity in leaves by 13%–17%, along with 3-fold stimulation in carbonic anhydrase activity. Cyanobacterium-amended foliar agents significantly enhanced soil dehydrogenase, urease activity, along with increments in organic carbon, Fe, Zn in soil and stimulated yield, fresh weight and quality of fruits. Both cyanobacterial formulations were promising in enhancing plant growth, fruit yield and quality, however, A. laxa also significantly improved microbiological activity and nutrient enrichment in soil. Future research is focused towards optimising the dose and storage life of such foliar agents for protected horticulture.