Interactive effects of salinity and macronutrient level on wheat. I. Growth

Abstract

Plant growth response to salinity is known to change under different fertility levels. The objective of this study was to investigate interactive effects of salinity and macronutrient level on growth and yield of spring wheat (Triticum aestivum L. cv. Lona), grown in hydroponic culture in growth chambers until grain maturity. Eight salinity levels, 0 to 150 mM NaCl, were established and 1, 0.2, and 0.04 strength Hoagland macronutrient solution (x HS) were designed as the levels of nutrient supply. Only small decreases in the grain yield of the main spike were found at 1 and 0.2 x HS with low and medium salinity (0 to 40 and 40 to 100 mM NaCl, respectively). Larger decreases in the grain yield of the main stem were found at either 0.04 × HS or at high levels of salinity (125–150 mM NaCl), being more marked at 0.2 than at 1 × HS. In contrast to the main spike grain yield, which was only slightly affected at 1 and 0.2 × HS with low and medium salinity, increasing salinity strongly decreased plant yield components except thousand grain weight. The salinity level associated with a 50% grain yield decrease was about 84, 72, and 31 mM NaCl for 1,0.2, and 0.04 × HS, respectively. Salt tolerance was higher at high (full HS) macronutrient concentration. At all macronutrient levels, plant grain yield decreases were mainly and closely related to decreased leaf and tiller numbers. This result suggests that salinity exerts its main effects during the early growth stages. The most promising strategies for increasing wheat yields in saline soils will be (i) increasing nutrient supply in nutrient‐poor soils, (ii) creating favorable conditions in the root zone during germination, seedling stage, and early tillering by salt elimination, and (iii) increasing main stem population density by increasing seeding density. The second and third measures will increase yields to a greater extent at moderate and sufficient nutrient levels than additional supplies of nutrients.