Reduction of Cracking in Pomegranate Fruit After Foliar Application of Humic Acid, Calcium-boron and Kaolin During Water Stress

Abstract

One of the primary physiological issues with cultivation of pomegranate (Punica granatum L. cv Post Sefid Darjazin) is excessive fruit cracking. Foliar applications of chemical and organic mixtures to limit or prevent pomegranate cracking were evaluated in this work. This 2 year study (2014–2015) was conducted in Darjazin, Iran and designed to evaluate the impacts of foliar application of 2 and 5 ml l−1 humic acid, 6% kaolin, and 3% Calcium-1% Boron (CB) separately or in combination. Pomegranate fruits were examined under two irrigation regimes at three time periods during the growing season. It was found that 14 day irrigation periods resulted in significantly more cracking in pomegranate than standard irrigation. Increased temperatures in 2015 contributed to higher percentages of fruit cracking as well. Foliar application of 6% kaolin significantly decreased cracking in 7 day irrigation studies while 2 ml l−1 humic acid, 6% kaolin, CB, and the combination of 6% kaolin/CB and 6% kaolin/2 ml l−1 humic acid reduced cracking under 14 day irrigation. Fruit weights significantly increased with 6% kaolin application and 7 d irrigation while 5 ml l−1 humic acid both increased pomegranate acidity and decreased the flavor index. Therefore, foliar application of kaolin and humic acid can reduce cracking in pomegranate fruit.