Emergence Rate, Yield, and Nitrogen-Use Efficiency of Sunflowers (Helianthus annuus) Vary with Soil Salinity and Amount of Nitrogen Applied

Abstract

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 [EC_e] = 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 (EC_e = 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 (EC_e = 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-salinity and high- or severe-salinity fields, respectively, in Hetao Irrigation District and similar sunflower-growing areas.

Keywords:

• Helianthus annuus
• nitrogen application rate
• nitrogen use efficiency
• net economic profit
• salinity

Additional information

Funding

This work was made possible by support from the State Natural Science Fund (Research on the Production Function of Water–Fertilizer in Saline Soil Based on Crop Growth Simulation, No. 51379151), the Fundamental Research Funds for the Central Universities (No. 2014206020201), and the China Scholarship Council (No. 201306270104).