DIFFERENTIAL TOLERANCE OF SOYBEAN (GLYCINE-MAX) TO MANGANESE IN MN-DEFICIENT SOIL

An experiment was conducted during rainy season (kharif) of 1989 to st udy the tolerance of 10 varieties of soybean [Glycine max (L.) Merr.] to manganese stress in a Mn-deficient field containing 2.4 mg DTPA-Mn/ kg soil. The treatments included the control and 3 foliar sprays of 0. 5% manganese sulphate solution. The seed yield of soybean was 86-254 g /2 m row length under Mn-stress condition. Though all the varieties re sponded to foliar application of Mn, the increase in seed yield varied from 1.0 to 25.0%. The Mn concentration in seeds of different varieti es was 10.3-14.3 mug/g and it significantly increased to 13.7-17.5 mug /g with the application of Mn. Based on the increase (%) in seed yield on foliar application of Mn, the varieties were grouped least toleran t ('PK 416', 'Pk 504' and 'SL 115'), moderately tolerant ('SL 96', 'SL 110', 'SL 114', 'Punjab 1' and 'SH 184-25') and tolerant ('SL 133' an d 'PK 472').