Effect of Frequency and Rate of Zinc Application on Nodulation, Chlorophyll Content, Yield, and Quality of Soybean Grown in a Vertisol of Jabalpur, Madhya Pradesh, India

Zinc (Zn) fertilizer is commonly used in nutrient intensively cultivated deficient soils of central, India. Zn is a structural components of plants. However, little is known, on optimum dose of Zn especially in a vertisol of Jabalpur district. This study was required to find out Zn dose for sustainable productivity and maintenance of soil fertility. The study comprised of three frequency levels, Zn application in 1st year only, Zn application in alternate year, and Zn application in every years and five rates of Zn, (0, 2.5, 5.0, 7.5, and 10.0 kg Zn ha-1) was applied in Kharif season. The result of analysis revealed that the highest symbiotic traits viz., nodule number of 36.78, fresh and dry weight (1.09 and 0.31 g plant-1) were found with application of 5 kg Zn ha-1 at 45 DAS at alternate year. The highest SPAD score of 44.98 and relative water content of 62.41 % was recorded with 5 kg Zn ha-1 at 60 DAS and found significant at alternate year. The Zn addition @ 5.0 kg ha⁻¹ through ZnSO4.7H2O to soybean in alternate year which increased by 1.28 to 1.53 (19.53 %) over only single year Zn addition. This was the best practice in a typic haplusterts as it resulted in an average production of 1.54 t ha-1 of seed yield ha⁻¹ over no zinc application (1.24 t ha-1) which increased by 24.19 %. The zinc application improved quality of seed in terms of oil and protein over control. So it was concluded that Zn application at alternate year and 5 kg Zn ha-1 for increasing yield and quality of soybean in a vertisol of Jabalpur district.