Comparison of leaf population of sweet cherry (Prunus avium L.) trees on different rootstocks

Abstract In a series of investigations, undertaken to find the optimal leaf area index (LAI) within the canopy of high density cherry orchards (Prunus avium L.) we studied the characteristics of the leaf population from sweet cherry trees on different rootstocks and their impacts on LAI. Our study involved measuring leaf surfaces, weighing and counting the leaves as well as calculating different indexes to evaluate the distribution of the leaf population. The investigations were carried out five (2008) and six (2009) years after plantation, on ‘Petrus’ and ‘Rita’ sweet cherry trees budded on the following rootstocks. ‘Petrus’ on two clonal Mahaleb rootstocks: ‘Bogdany’, ‘Magyar’ and also on two interspecific hybrids: ‘Gisela 6’ and ‘Prob’. ‘Rita’ trees were grafted on Prunus mahaleb seedlings: ‘Korponay’, P. avium seedlings and on ‘Gisela 6’ rootstocks. The average single leaf area (SLA) of both cultivars was larger on extension shoots compared to spurs. This large single leaf size difference impacts the total leaf area (TLA) of the tree. Leaves from trees on dwarfing rootstocks usually show larger specific leaf weight (SLW), while on vigorous rootstocks the SLW on both shoot type was smaller. On the other hand, there is a tendency that spur-leaves show lower SLW compared to extension shoots. The rootstock vigor strongly influenced the LAI and so the leaf density within canopy space. Both ‘Rita’ and ‘Petrus’ trees tend to develop a proportionally larger spur leaf canopy on dwarfing rootstocks, and this tendency is even stronger after heading the trees ( Table 6 ), while trees on ‘Magyar’ and ‘Bogdany’ rootstocks have consistently low SPLA rates.