Phenology and yield evaluation of hazelnut cultivars in Latium region

In central Italy (Latium), hazelnut cultivation is carried out using only a few round-shaped nut producing cultivars including ‘Tonda Gentile Romana’, ‘Tonda di Giffoni’ and ‘Nocchione’ as main pollinizer. With the aim to extend the hazelnut genetic base a variety collection was established in a typical hazelnut-growing area of Viterbo province. The collection consists of 48 cultivars, each represented by three multi-stemmed trees. Flowering time, female and male full bloom, leaf budbreak, and leaf fall of each cultivar were recorded over three years (2014-2016). Sucker production and vigor of the trees were also measured. Further, nut yield and nut and kernel traits were investigated. On average, ‘Tonda Rossa’, ‘Karidaty’, ‘Sivri A’ and ‘Tonda Gentile delle Langhe’ showed a very early period of pollen shed, which was concentrated in the middle of December. In respect to female bloom, the earliest female bloom was in ‘Nostrale’, ‘San Giovanni’ and ‘Tonda di Giffoni’, which showed style emergence (red-dot stage) at the end of November. ‘San Giovanni’ and ‘Tonda di Giffoni’ also showed an early leaf budbreak, which occurred in mid-February, and this early vegetative growth could make this cultivar vulnerable to frost injury. ‘Camponica’ showed the highest yield over the period of investigation, and ‘Nociara’ showed the highest yield efficiency.