The effects of foliar applied potassium in the mineral form and complexed with amino acids on pistachio nut yield and quality

ABSTRACT

A two-year field experiment was conducted to investigate the effects of foliar-applied K in the form of mineral compound (K₂SO₄) and complexed with lysine (KL) and lysine plus methionine (KLMet) with or without ascorbic acid (A) on nut yield and quality of bearing pistachio (Pistachio vera L. cv. Owhadi). Results showed that foliar application of K, regardless of applied source, significantly increased leaf and nut K concentration in comparison with control. In both experimental years, the trees supplemented with K provided higher total yield, fresh and dry mass of shelled and unshelled 100-nut, and 100-kernel dry mass and lower percentage of non-split shells in comparison with those un-supplemented with K. In both years, foliar application of K significantly decreased the percentages of blank nuts. The effectiveness of K-amino chelates in improving nut yield and quality was, in general, higher than that of K₂SO₄. The highest yield and the best nut quality was obtained with foliar application of KLMet-1. The critical leaf and nut K concentration for optimum pistachio nut yield and quality was 2.27 and 1.87%, respectively. Foliar application of K particularly in the form of KLMet-1 during nut filling is recommended to obtain optimum yield and quality of pistachio.

KEYWORDS:

• Amino acids
• fertilization
• lysine
• methionine
• Pistacia vera L

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The investigation was financially supported by Iranian Knowledge-Cased Company of Zist Fanavaran Novin Qom.