Phenological growth stages of pistachio (Pistacia vera L.) according to the extended BBCH scale: Description and chronological characterization in a Mediterranean environment

Abstract

Pistachio (Pistacia vera L.) is considered one of the most important tree nuts worldwide, for its high nutritional and economic value. Recently, its cultivation is expanding into different regions which climatic conditions are highly affected by global warming, particularly Mediterranean regions. In this context, understanding the phenological response of this plant is becoming an essential tool for optimizing yields and quality. In other species, this monitoring is possible thanks to the BBCH scale. This study represents a detailed characterization of the phenological growth stages of pistachio, including five female cultivars: ‘Kerman’, ‘Sirora’, ‘Aegina’, ‘Larnaka’ and ‘Lost Hills’ and two male cultivars represented by ‘Peters’ and ‘Randy’, using this scale in order to provide an efficient tool for researchers and growers. Through monitoring of two consecutive years (2024 and 2025), we codified and described both vegetative and reproductive phenology including 56 stages in total. For a clear identification of these stages, our study provides illustrative images for each phase. In addition, our data has helped to determine the chronological progression of growth in some of the most commonly grown cultivars under the climatic conditions of southern Spain. These findings are expected to enhance the efficiency of pistachio research, management and breeding.