Effect of watertable on yield and root depth of winter wheat in the French West Central Atlantic Marshlands

Abstract

The watertable in winter depends on the field drainage system and the structural stability of the soils. The yield of winter wheat and the nitrogen supply of the soil are positively correlated with a lower water-table. Therefore, the mean watertable in winter is a good environmental indicator for the yield potentialities For the explanation of yield variations, the depth of the root system was observed at the start of stem elongation and the anthesis. At the start of stem elongation, the root depth (E i) increases with a lower watertable in winter (r = 0.931). The root depth after anthesis (E f) depends on the root depth at stem elongation (E i) and on the climatic balance R (rainfall)-ET (evapotranspiration) between these two stages. For R>ET, R = ET and R<ET, root growth (dE = E f−E i) is respectively almost zero, decreases with increasing E i (“growth of roots making up for lost time”) or increases with increasing E i (“homothetic growth”). The root depth studies explain the relation between the pedoclimatic and environmental conditions and the yield of winter wheat.