Nitrogen Source Preference in Maize at Seedling Stage Is Mainly Dependent on Growth Medium pH
2022
Hao-Qing Zhang | Ren-Fang Shen | Xue-Qiang Zhao
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&minus: is affected by pH and to determine the critical pH controlling this preference. Maize plants were grown with NH4+ or NO3&minus: in different soils (pH 4.32&ndash:8.14) and nutrient solutions (pH 4.00&ndash: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&minus:, NH4+ decreased maize dry weight, N uptake, and NRE by 28&ndash:94% at soil pHs of 4.32 and 4.36 and a solution pH of 4.00, whereas it increased these parameters by 10&ndash:88% at soil pHs of 6.52&ndash:8.02 and solution pHs of 7.00 and 8.00. NO3&minus: increased soil pH and decreased soil exchangeable Al content at soil pHs of 4.32&ndash:6.68. Critical soil and solution pHs for changing plant growth and N uptake preference for NH4+ vs. NO3&minus: 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&minus: mainly depends on the pH of the growth medium, and maize seedlings generally prefer NO3&minus: in strongly acid soils but NH4+ in neutral to alkaline soils.
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