ISHS Acta Horticulturae 792: V International Symposium on Irrigation of Horticultural Crops
RECENT ADVANCES IN REGULATED DEFICIT IRRIGATION (RDI) IN WOODY PERENNIALS AND FUTURE PERSPECTIVES |
| Authors: | J. Marsal, G. Lopez, J. Girona |
| Keywords: | stem water potential, fruit load, soil depth, winter root reserves, water stress indicators |
| Abstract:
The renewed interest in regulated deficit irrigation (RDI) has evolved from an initial interest in controlling plant vigor to other advantages such as water conservation and improving fruit quality. However, not all species respond well to RDI. This paper considers the recent advances in RDI knowledge under a broad range of conditions. First, we compare short-term (first year) with long-term responses (third year) in relation to tree size and productivity. Secondly, we examine the sensitivity to recovery from water stress under high crop loads. Thirdly, we consider soil conditions, which must be taken into account when managing water stress during periods of deficit irrigation. Generally speaking, it is important to consider general agronomic and climatic conditions as they may play an important role in determining expected responses to RDI. A well-designed RDI strategy works well during the 1st year in almost all cases. However, species whose yields depend more on their fruit bearing capacity and fruit numbers than on fruit size (such as almond and olive trees) are the most likely to have their yields affected by reductions in tree size during subsequent years. The practice of thinning and pruning in species with a premium on fruit size tends to reduce tree size limitations on tree fruit numbers, and to increase the chances of RDI being more sustainable. The other significant factor, high fruit load, tends to make the trees of certain species more sensitive to the development of water stress and may also delay recovery from it. In such cases, the level of stress managed during the period of deficit irrigation needs to be adapted to the sensitivity of the species. Future work should focus on developing specific knowledge to help define appropriate stress levels for each particular case and should be aimed at achieving greater control over plant water stress during periods of deficit irrigation. These two improvements are required if RDI is to be made more accessible and less risky for commercial purposes. | |
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