Abstract
Salinity stress as well as water stress impairs crop production in saline soil. This study was conducted to examine the effect of soil salinity on water use and dry matter production in wheat and barley. Long pots, 96 cm in length and with an inner diameter of 7.1 cm, were filled with sieved soil, and a NaCI solution was applied to establish saline plots NaCl-7 g and NaCl-14 g, in which the amount of NaCI was 7 and 14 g pot-1, respectively. No NaCl was applied to the NaCl-0 g plot. The seedlings of wheat cultivar “Norin 71” and barley cultivar “Hojo-kawa 8” were transplanted two plants per pot. When transpiration decreased to a negligible amount, shoot dry weight, root length, soil water and Na+ concentration of plant and soil were determined. The results were similar in the two crops. The number of stems per plant was smaller in NaCl-14 g than in NaCl-0 g or NaCl-7 g. The evapotranspiration rate increased at the same rate in all plots in the early growth stage, but, was larger in NaCl-0 g than in NaCl-7 g or NaCl-14 g in a later growth stage. The deeper the soil layer, the lower the root length density but the higher the volumetric soil water and Na+ contents. A correlation was observed between the soil water content and root length density, but there was a stronger relationship between volumetric soil water content and Na+ content. Reduction of shoot dry weight corresponded to that of total evapotranspiration. It was concluded that shoot dry weight was limited by the amount of water extracted from soil, which depended partially on root length density but mainly by soil Na+ content in saline soils.
