ISHS Acta Horticulturae 92: Symposium on Mineral Nutrition and Fruit Quality of Temperate Zone Fruit Trees
GENERAL DISCUSSION OF THE MINERAL NUTRITION OF FRUIT TREES |
| Authors: | Chair G. BÜNEMANN, K.J. TREHARNE, C.A. PRIESTLEY |
| Abstract:
Dr. J.E. Jackson presented a summary of major points of general agreement that had emerged, in particular that mineral nutrition of the plant was interactive and it was necessary to consider together the soil, the root interface, movement through the plant and in particular to the fruit. He considered it essential that in research on nutrition in different systems that the tree characters must be adequately described to permit correct evaluation and interpretation of data. It was also clear that different nutrients assumed greater importance according to species and management system and commented that while nitrogen was important for grass, it was not a dominant fertilizer requirement, although important, for apple trees in modern orchard systems. He drew attention to the fruit as the target for nutrition research as a major consideration in making decisions on tree management either in root or foliar application. Dr. Jackson presented various themes of work which he considered focal points for future action. In soil management he pointed out that mineral availability was affected more by herbicides than by fertilizer dressings but that there were many unresolved problems following herbicide use, such as low phosphorus, changes in pH leading to toxicity, effects on soil organisms and structure. He also raised the implications for nutrition of plastic mulches which also provide weed and water control but need to be examined fundamentally with respect to nutrient availability. On tree management, with moves to intensive systems, there have been unquestionably large changes in the balance of nutrition, in that an increasing proportion of nutrient resources were diverted to fruit, while root size and distribution were changing and needed definitive study. Considering the impact of breeding for nutritional problems, while commercial growers wanted to retain the same varieties, there is a commercial selection pressure towards varieties with potential for long-term storage which opposes the natural situation. Moreover, there are rootstock varieties which are more efficient in the uptake of calcium and others which are inefficient in this respect, which presents scope for selection. On the subject of fruit versus tree nutrition, Dr Jackson suggested that there was some scope for the concept of analogy with electrical flow as was applied to water relation studies. The fruits are at the end of a long flow | |
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