STUNTING SYNDROME IN PEANUTS AND AGRONOMIC APPROACHES FOR ITS RELEASE

Stunting of peanuts (Arachis hypogaea L.) was observed in newly cultiv ated areas of commercial fields, or following soil fumigation. Applica tion of Vapam (metham sodium) in three commercial peanut fields elimin ated the native VAM infection between soil surface and a 20 cm soil de pth when 60% reduction in VAM colonization was found at a soil layer o f 20-60 cm with no significant changes observed at deeper soil layers. Screenhouse and field experiments were performed to test new approach es to repress this syndrome. Various mineral treatments involving addi tional applications of Zn, P or N to the plants or inoculation of pean uts with vesicular-arbuscular mycorrhizal (VAM) fungus were studied. T he screenhouse experiment revealed that application of the VAM fungus Glomus macrocarpum curtailed the stunting effect at three different N levels (0, 4 and 12 mM KNO3). The addition of Zn or micronutrients soi l fumigation with Vapam elicited the same response as with the VAM fun gus. An increase in the shoot dry weight, albeit to a much lesser exte nt than that obtained by the addition of Zn or VAM was achieved by enh ancing P availability. The stunting syndrome was also reduced under fi eld conditions by the same treatments.