Effects of soil moisture on the germination and emergence of sugar beet (beta vulgaris l.)

Authors

• Erkki Aura Department of Agricultural Chemistry, University of Helsinki

DOI: https://doi.org/10.23986/afsci.71841

Abstract

By means of theoretical calculations and laboratory experiments, this study attempted to elucidate the effects of excessive and of inadequate soil moisture on the germination and seedling emergence of sugar beet. The results of this study confirmed the opinion that water contained in the sugar beet seed or surrounding the seed as a water film is a barrier to the adequate intake of oxygen by the seed only when the value of the water potential is close to zero. The soil water potential at which the passage of oxygen into the seed is prevented depends largely on the structure of the seed bed. With a semi-permeable membrane of cellulose acetate and a solution of polyethylene glycol, it was shown that the sugar beet seed will still germinate fairly well at a potential of —10 atm, but at —13 atm germination is slight. The soil water potential appeared to have nearly the same effect on germination as did the water potential of the polyethylene glycol solution. The seedling emergence percentage was, however, smaller than the germination percentage in experiments with the semi-permeable membrane. This was considered to be caused by the slow extension growth of the radicle due to a low water potential, at the stage of seedling emergence. According to studies made, the initial water intake of the sugar beet seed planted in soil is rapid. Poor contact between the seed and the soil slows down water intake and seedling emergence, but does not impair the final seedling emergence. Removal of the fruit coat was shown to improve germination markedly when the water potential is low. This treatment would have little practical significance, since the growth of the radicle at a low water potential is very slow.