Emergence Rate, Yield, and Nitrogen-Use Efficiency of Sunflowers (<i>Helianthus annuus</i>) Vary with Soil Salinity and Amount of Nitrogen Applied
For understanding the effects of soil salinity and nitrogen (N) fertilizer on the emergence rate, yield, and nitrogen-use efficiency (NUE) of sunflowers, complete block design studies were conducted in Hetao Irrigation District, China. Four levels of soil salinity (electrical conductivity [ECe] = 2.44–29.23 dS m−1) and three levels of N fertilization (90–180 kg ha−1) were applied to thirty-six microplots. Soil salinity significantly affected sunflower growth (P < 0.05). High salinity (ECe = 9.03–18.06 dS m−1) reduced emergence rate by 24.5 percent, seed yield by 31.0 percent, hundred-kernel weight by 15.2 percent, and biological yield by 27.4 percent, but it increased the harvest index by 0.9 percent relative to low salinity (ECe = 2.44–4.44 dS m−1). Application of N fertilizer alleviated some of the adverse effects of salinity, especially in highly saline soils. We suggest that moderate (135 kg ha−1) and high (180 kg ha−1) levels of N fertilization could provide the maximum benefit in low- to moderate-sa...