Effect of Casuarina equisetifolia litter on CO_2 assimilation and aboveground biomass of cauliflower （Brassica oleracea var. botrytis）

摘要

Agriculture can be hindered by low soil nutrient availability, leading to the need for nutrient amendments to maintain crop productivity. Casuarina equisetifolia, commonly known as Australian pine, is a highly invasive species that represses native plant growth, but some studies have suggested that C. equisetifolia litter could be used as an agricultural amendment. Our objective was to investigate the effects of C. equisetifolia litter on cauliflower productivity. In a greenhouse experiment, individual cauliflower seeds were grown in pots with no litter addition, non-composted litter, or composted litter. We hypothesized that cauliflower in the composted litter treatment would have the highest carbon assimilation, biomass, and number of leaves. We found no effect of treatment on carbon assimilation, which suggests that C. equisetifolia litter does not increase nitrogen (N) availability. Aboveground biomass of cauliflower and the number of leaves per plant were lower in the composted litter treatment than in the non-composted litter or control treatments. This suggests that composted C. equisetifolia litter had allelopathic effects on cauliflower or facilitated an increase in microbial biomass, which increased competition and reduced the amount of N available for cauliflower. This study indicates that C. equisetifolia litter is not an ideal soil amendment for cauliflower production due to its potential allelopathic and inhibitory effects when composted and its inability to increase productivity when not composted.