An automated greenhouse sand culture system suitable for studies of P nutrition |
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Authors: | J. LYNCH,E. EPSTEIN,A. LÄ UCHLI,G. I. WEIGHT |
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Affiliation: | Department of Land, Air and Water Resources, University of California, Davis, CA 95616, U.S.A. |
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Abstract: | Abstract. Maintenance of realistically low solution P concentrations under controlled conditions is a major difficulty in studies of P nutrition. In this report, we describe a relatively simple and economical sand culture system capable of sustaining plant growth to maturity under controlled yet realistic P regimes. The system uses Al2O3 as a solid-phase P buffer, and modern process control technology to control irrigation and addition of other mineral nutrients. Aspects of the design, use and potential applications of automated solid-phase systems are discussed. The system was used to grow Phaseolus vulgaris to matarity at 0.4 mmol m3, 1.0 mmol m3 and 27 mmol m3 P with and without mycorrhizal inoculation. At flowering, low solution P concentrations were associated with reduced leaf concentrations of P in nonmycorrhizal plants, and reduced leaf concentrations of Ca in both mycorrhizal and nonmycorrhizal plants. Mycorrhizal inoculation increased leaf P, K, Mg and Mn concentrations, but reduced leaf N concentration. Low P regimes reduced final seed yield by diminishing both the number of pods per plant and the number of seeds per pod. Mycorrhizal inoculation significantly enhanced seed yield under low P regimes by increasing seed weight, the number of pods per plant, and the number of seeds per pod. |
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Keywords: | Phascolus vulgaris L Glonus macrocarpum automated nutrient culture Al2O3 solid-phase P buffer |
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