Effect of soil moisture condition and irrigation regime on bioelectric potential of crops at different growth stages

The objective of this study was to evaluate the effect of soil moisture condition and irrigation regime on the bioelectric potential of crops with different growth stages. The bioelectric potential of broccoli (Brassica oleracea var. italica) plants at the initial and mid-growth stages was measured under different soil moisture conditions and irrigation regimes using pot experiments. The results indicated that the bioelectric potential varied as a function of the soil moisture, irrigation regime, and stage of crop growth. To more accurately clarify the relationship among the changes in bioelectric potential, soil moisture, and crop growth stage, a wavelet analysis was performed. The results showed that the bioelectric potential changed as a function of both soil moisture and crop growth stage. Further, the dominant frequency band under wet soil condition at the initial growth stage before irrigation had a large wavelet coefficient compared with the results obtained under the other soil moisture conditions. In the mid-growth stage, the dominant frequency bands under wet and intermediate soil conditions were similar before and after irrigation. However, the characteristics of the wavelet conversion chart under dry soil conditions changed after irrigation. The results showed that the growth stage and irrigation regime both affect the crop bioelectric potential. Although clarifying the relationship among the bioelectric potential, soil moisture and crop growth stage was difficult, the wavelet analysis was shown to be effective for evaluating the effect of soil moisture and crop growth stage on the bioelectric potential. The results of the analysis indicated the bioelectric potential could be an important indicator for managing soil moisture and for optimizing irrigation regimes.