Response of French Bean (Phaseolus vulgaris L.) Cultivars to Foliar Applications of Magnesium

Magnesium deficiencies have been shown to be particularly dangerous to short cycled crops, both on sandy andclay soils. Such deficiencies may be corrected by foliar fertilisations, but in French bean (Phaseolus vulgaris L.) noexperimental data may be found to support this hypothesis. Therefore this paper was aimed at studying the effectof foliar Mg-applications (56, 112 and 224 g har in single application at flowering or splitted half dose at 4-leaÎstage and half at flowering) alone and with Zn (200 g ha 1) on yield and quality of two French bean genotypeslBronco. Cadillac).Èotar Mg-applications significantly increased pod yield and, considering the highest rate with respect to the untreated,*"fr un increase was 787o and 32o/o for Bronco and Cadillac, respectively. Split applications were also moreeffective, with yield increases of 109% and 50% for the two genotypes. Concerning qualìty, foliar Mg applicationsshowed a significant effect particularly on sugars, calcium, phosphate, sulphate and Mg contents in pods. On theother hand,-asignificant effèct on the accumulation of nitrates was noted, especially with split applications (L44%increasev s. unfertilised) and, in some casesa, n antagonistice ffect on K content (10-20% decreaseo n average).Foliar Mg fertilisation of French bean seemed to be a promising practice with reÎerence to human health and nutrition,tough some care is needed to avoid the accumulation of nitrates in pods. Split applications seemed to bemore effective. while the addition of Zn to the fertiliser mix did not give any relevant effect.[...]