Nitrogen Source Preference in Maize at Seedling Stage Is Mainly Dependent on Growth Medium pH

• Published in: Agronomy (Basel) Vol. 12; no. 9; p. 2149
• Main Authors: Zhang, Hao-Qing, Shen, Ren-Fang, Zhao, Xue-Qiang
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.09.2022
• Subjects: Acidic soils; agronomy; Alkaline soils; Aluminum; ammonium; Corn; critical pH; Culture media; Dry weight; Ethylenediaminetetraacetic acid; exchangeable aluminum; Fertilizers; Flowers & plants; Food supply; Growth; Hydrogen-ion concentration; nitrate; Nitrogen; nitrogen content; nitrogen recovery efficiency; nitrogen uptake; Nutrient solutions; pH effects; Plant growth; seedling growth; Seedlings; Seeds; Soil chemistry; Soil pH; Soils; Water, Underground; Zea mays; China
• ISSN: 2073-4395; 2073-4395
• DOI: 10.3390/agronomy12092149

To improve crop nitrogen recovery efficiency (NRE), plants must be supplied with their preferred form of nitrogen (N). However, whether pH affects crop N-form preference remains unclear. Here, we aimed to explore how maize (Zea mays L.) preference for NH4+ and NO3− is affected by pH and to determine the critical pH controlling this preference. Maize plants were grown with NH4+ or NO3− in different soils (pH 4.32–8.14) and nutrient solutions (pH 4.00–8.00). After harvest, plant dry weights, N content, N uptake, NRE, soil pH, and exchangeable aluminum (Al) were measured. Compared with the effect of NO3−, NH4+ decreased maize dry weight, N uptake, and NRE by 28–94% at soil pHs of 4.32 and 4.36 and a solution pH of 4.00, whereas it increased these parameters by 10–88% at soil pHs of 6.52–8.02 and solution pHs of 7.00 and 8.00. NO3− increased soil pH and decreased soil exchangeable Al content at soil pHs of 4.32–6.68. Critical soil and solution pHs for changing plant growth and N uptake preference for NH4+ vs. NO3− ranged from 5.08 to 5.40 and from 5.50 to 6.59, respectively. In conclusion, the preference of maize seedling growth and N uptake for NH4+ vs. NO3− mainly depends on the pH of the growth medium, and maize seedlings generally prefer NO3− in strongly acid soils but NH4+ in neutral to alkaline soils.