Effect of Ca(NO_3)_2 or KNCVCafNO~- floral initiation spray schedules on flowering intensity and yield in 'Keitt' mango, and the additional effect of spraying with Speedfol during flowering

摘要

In the vicinity of Petrolina, Brazil, fruit-bearing 'Keitt' trees were treated via the soil with paclobutrazol in mid-February 2014. Half of the trees were sprayed twice with potassium nitrate (KNO_3J and then twice with calcium nitrate [Ca(N03)2]- The remaining half were sprayed four times with Ca(NO_3)_2. The sprays were made every 5 days to effect the initiation of inflorescence development. Paclobutrazol was applied 90 days prior to the commencement of spraying. In addition, when the inflorescences generally exhibited 20% bloom and again when they generally exhibited 80% bloom, Speedfol Mango Set Lift, a mineral nutrient formulation, was spray-applied on half of the trees. The sprays of Speedfol were effective in stimulating the initiation of additional inflorescences from buds breaking when general inflorescence development was already underway in the trees sprayed with KNO_3/Ca(NO_3)_2. Greatest flowering intensity occurred following KN03/Ca(NO_3)_2 and Speedfol spraying. A reduction in flowering intensity occurred in the trees sprayed with Speedfol and Ca(NO_3)_2. Here, Speedfol spraying stimulated bud break, but the development of new shoots and not inflorescences. Number of fruits and fruit yield were greatest in the trees sprayed with KNC3/Ca(NO_3)_2 and Speedfol; this related directly to the effect of these sprays on flowering intensity. It was apparent that Speedfol specifically increased fruit retention, as the trees sprayed with Ca(NC_3)_2 and Speedfol showed increased fruit numberand yield when compared with the trees sprayed only with Ca(NO_3)_2. The results indicate that KNO_3/Ca(N_3)_2 followed by Speedfol spraying is superior in endeavoring to maximize flowering intensity and yield in mango trees grown in tropical climates.