Articles
Performance of micropropagated walnut orchards trained to central leader in Emilia-Romagna, Italy
Article number
1420_19
Pages
145 – 152
Language
English
Abstract
Walnut cultivation in Emilia-Romagna region (Po Valley, Italy) is recent and still marginal, but expanding.
The new walnut orchards are established with lateral fruiting cultivars, mainly ‘Chandler’, specialized and irrigated.
The central leader is the most popular training system, relatively easy to manage and suitable for mechanical pruning.
Although the trees grafted onto J. regia are currently the most planted, micropropagated plants of various sizes and nursery cycles are also commercially available, often at a more competitive price compared to grafted materials.
In our study, we evaluated the growth and yield performance of various micropropagated trees planted in commercial orchards, whenever possible in comparison with grafted materials.
All micropropagated materials showed intense vegetative growth since planting, and even the 0.1-0.2 m tall MI_11 plants, produced with a few-month nursery cycle, were able to develop a >2 m long leader during the first leaf, and numerous and well-distributed shoots along the leader in the second growing season.
Regardless of the type of nursery material, minimal and rapid pruning interventions on the leader and the main scaffold limbs were sufficient to manage the central leader formation and, by the end of the fourth growing season, the tree training phase was practically finalized.
All micropropagated trees produced pistillate flowers since the first leaf; however, in the early planting years, we observed a blooming delay of 10-11 days compared to grafted trees of the same cultivar and age.
In some of the trials under observation, the yield performance was unsatisfactory (0.3 and 0.5 t ha‑1 at the fourth and fifth leaf, respectively, 64 and 44% less of grafted trees). In areas where walnut growing is marginal, the delay in female flower receptivity of micropropagated plants reduces the chance of intercepting environmental pollen.
Indeed, in the trials where artificial pollination was applied, over 50% of flowers set up fruits, for a yield of 0.5-0.8 (3rd leaf) and 1.5 t ha‑1 (4th leaf).
The new walnut orchards are established with lateral fruiting cultivars, mainly ‘Chandler’, specialized and irrigated.
The central leader is the most popular training system, relatively easy to manage and suitable for mechanical pruning.
Although the trees grafted onto J. regia are currently the most planted, micropropagated plants of various sizes and nursery cycles are also commercially available, often at a more competitive price compared to grafted materials.
In our study, we evaluated the growth and yield performance of various micropropagated trees planted in commercial orchards, whenever possible in comparison with grafted materials.
All micropropagated materials showed intense vegetative growth since planting, and even the 0.1-0.2 m tall MI_11 plants, produced with a few-month nursery cycle, were able to develop a >2 m long leader during the first leaf, and numerous and well-distributed shoots along the leader in the second growing season.
Regardless of the type of nursery material, minimal and rapid pruning interventions on the leader and the main scaffold limbs were sufficient to manage the central leader formation and, by the end of the fourth growing season, the tree training phase was practically finalized.
All micropropagated trees produced pistillate flowers since the first leaf; however, in the early planting years, we observed a blooming delay of 10-11 days compared to grafted trees of the same cultivar and age.
In some of the trials under observation, the yield performance was unsatisfactory (0.3 and 0.5 t ha‑1 at the fourth and fifth leaf, respectively, 64 and 44% less of grafted trees). In areas where walnut growing is marginal, the delay in female flower receptivity of micropropagated plants reduces the chance of intercepting environmental pollen.
Indeed, in the trials where artificial pollination was applied, over 50% of flowers set up fruits, for a yield of 0.5-0.8 (3rd leaf) and 1.5 t ha‑1 (4th leaf).
Publication
Authors
D. Giovannini, F. Brandi, S. Sirri, F. Massetani, E. Cozzolino, D. Neri
Keywords
Juglans regia, intensive plantings, nursery stock material, pruning
Groups involved
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