ISHS Acta Horticulturae 481: International Symposium on Growing Media and Hydroponics
IMPROVEMENT OF TOMATO FRUIT QUALITY BY CALCIUM NUTRITION |
| Authors: | Lim C. Ho, David J. Hand, M. Fussell |
| Keywords: | Tomato, calcium, fruit quality, blossom-end rot, goldspot, nutrition |
| Abstract:
Some fruit quality defects in tomato resulting from physiological disorders may be caused by either local Ca deficiency (e.g. blossom-end rot) or local Ca excess (e.g. gold spot) in the fruit tissue. The supply of Ca is commonly more than adequate for plant development and is unlikely to be the primary cause of BER. However, the uptake of Ca can be reduced by high EC, poor aeration or adverse temperature of the root zone. Furthermore, the transport of Ca to the fruit is intrinsically low, as most of the Ca is transported to leaves by canopy transpiration. Therefore, a combination of low uptake and low transport of Ca to the fruit can cause a low Ca status in the fruit. The demand for Ca for cell expansion in rapidly growing fruit, particularly in the distal pulp tissue may not be met, if the import of Ca is low and the xylem transport resistance within the fruit is high. Environmental conditions required for high yield, such as high light, CO2 and temperature stimulate fruit expansion, but may not increase and may even reduce the transport of Ca to the susceptible distal tissue of the fruit. Therefore, the incidence of BER is determined by the fruit growth response to the environmental conditions during the rapid phase of fruit enlargement. However, the symptom of BER may not be entirely caused by low Ca in the fruit tissue itself, but its interactions with N and P in maintaining the cell membrane permeability and cell wall structure. Conversely, the occurrence of goldspot in the ripe fruit, mainly late in the season, is enhanced by high temperature but is reduced by low Ca and high K supply. Optimisation of Ca nutrition to avoid Ca related fruit quality problems is presented. | |
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