Pistachio performance in the southern Mediterranean: towards optimal use of genetic resources to increase productivity of rainfed agriculture

Rainfed agriculture in Mediterranean countries is tending to become less productive under an increasingly warming climate. To improve this productivity, optimal use of available resources is of strategic concern. The cultivation of the pistachio ( Pistacia vera L.), a species well adapted to arid areas in Tunisia, is, however, a low-productive crop. Little information is currently available on the the high genetic diversity that constitutes the main barrier to the optimal cultivation of this crop. The aim of this study was to improve current knowledge on the behaviour of eight local (“Mateur”, “El Guettar”, “Meknassy”, “LG 1 ” and “LG 2 ”) and foreign (“Ohadi”, “Amiri” and “Jawad”) pistachio accessions currently grown under rainfed conditions in northeastern Tunisia. Phenological events, average nut yield per tree, yield efficiency and nut characteristics were determined during the 2015–2017 crop periods. The results showed variable impacts of warm climate and rainfed growing conditions on the studied accessions. Flower setting occurred ealier in local accessions than in Iranian cultivars that require a higher chill amount. Tree fruit yield varied between 2.8 and 11.1 kg. The “LG2”, “El Guettar” and “Mateur” accessions were the most productive of those tested (10.4–11.1 kg/tree), while accessions “Meknassy”, “Amiri” and “Jawad” accessions performed the least (2.8–3.7 kg/tree). The vigorous “El Guettar” and the low vigorous “Amiri” cultivars showed a higher yield efficiency than did cvs. “Jawad” and “Meknassy” cultivars with high and middle vigour, respectively. “LG 2 ”, “El Guettar” and “Mateur” accessions exhibited better adaptation. “Jawad” cultivar produced the largest nuts while “El Guettar” and “LG1” accessions the smallest. Specific technical practices are suggested to improve yield performances of the studied accessions, including moving pistachio orchards to most favourable climate regions.