Critical Boron Concentration and Response of Hydrolytic Enzymes in Maize (Zea mays L.) Plants

Critical boron concentration and response of hydrolytic enzymes in maize (Zea mays L. var. 32-A09) plants was assessed under controlled conditions. Maize (Zea mays var. 32-A09) plants were grown in sand culture under glass house condition till maturity with application of boron ranging from 0.033 to 6.6 mg L⁻¹. Plants of maize had higher requirement of boron and optimum yield was obtained in plants getting 0.66 mg L⁻¹ of boron application and levels below and above this exhibited deficiency and excess symptoms of boron, respectively. The critical boron concentration for optimum vegetative yield was found to be 21.5 to 40 ìg boron g⁻¹ dry weight. Plants showed growth retardation and characteristic visible symptoms, decreased dry matter yield and reproductive yield under deficiency and excess of boron. Activities of hydrolytic enzymes– acid phosphatase (APase) and ribonuclease (RNase) were increased in boron deficient and excess plants.