ISHS Acta Horticulturae 644: International Symposium on Growing Media and Hydroponics
YIELD AND NUTRIENT STATUS IN THE ROOT ENVIRONMENT OF TOMATOES (LYCOPERSICON ESCULENTUM) GROWN ON CHEMICALLY ACTIVE AND INACTIVE INORGANIC SUBSTRATES |
| Authors: | D. Savvas, K. Samantouros, D. Paralemos, G. Vlachakos, M. Stamnatakis, C. Vassilatos |
| Keywords: | soilless culture, hydroponics, nutrient solution, zeolite, perlite, diatomite |
| Abstract:
Tomato plants were grown in perlite (control), zeolite, and mixtures of perlite and zeolite (78:22 v/v), zeolite and diatomite (60:40 v/v) perlite and diatomite (75:25 v/v) and perlite, diatomite and zeolite (80:11:9 v/v). All substrate treatments were supplied with nutrient solution having the same composition. The Mg concentration in the nutrient solution supplied to the plants was high because the available raw water contained 8.70 meq L-1 Mg. The drainage water was left to run off throughout the cropping period. The early yield was significantly higher in perlite. However, after 3 months of harvesting, the highest yield was obtained from the plants grown in zeolite, followed by the treatment involving zeolite and diatomite, due to an enhanced mean fruit weight. The mixture of perlite with either diatomite, or zeolite, or both, resulted in the lowest yields. The better performance of the plants grown in zeolite or zeolite and diatomite was ascribed to the considerable cation exchange capacity of the former, which enabled a more efficient buffering of excess ammonium and Mg concentrations in the root environment. In contrast, under the specific conditions of the present trial, the lack of buffering capacity in perlite resulted in too high NH4+ concentrations and hence in too low pH levels in the root environment of the plants. Moreover, zeolite was capable of adsorbing part of the excess Mg, thus resulting in more balanced macronutrient cation ratios in the root environment. On the other hand, during the initial wetting of the substrates with nutrient solution, most of K was adsorbed on the surface of zeolite. As a result, the K concentration was sharply reduced in the drain solutions collected from substrates including zeolite as a constituent. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
