USING DEFOLIATION TO ESTIMATE YIELD LOSSES IN CAULIFLOWER - APPLICATION IN HAIL DAMAGE ASSESSMENT

Experiments were designed to assess the effects of defoliation and ben ding back petioles on the head mass of cauliflower (Brassica oleracea L. var. botrytis Alef. subvar. cauliflora. cv. Matra) in the Central E bro Valley of Spain. Treatments were applied at seven different stages during the growth cycle. Defoliation reduced final head mass, the amo unt of the reduction increasing with level of defoliation. Bending bac k the petioles produced a loss in head mass intermediate between that caused by 33% and 66% defoliation. In all four trials, mass loss was h ighest when defoliation occurred at a head diameter between 20 and 38 mm. Neither defoliation nor bending of the petioles appeared to influe nce head induction or length of the production cycle. Maximum loss of head mass (85.4% to 64.9%) occnrred when cauliflower was totally defol iated at a head diameter of 20-25 mm.