Decoding the Impact of Nitrogen Forms on Plant Growth in Soilless Culture

Sunil Gurung, Tennessee State University


Plants can utilize two major nitrogen forms: ammonium (NH4) and nitrate (NO3). Plant’s response to N forms varies with genotypes, relative proportions of N forms (NH4:NO3), N rate, pH and growing medium composition. Growth and physiological responses of 16 genotypes (1 cereal, 2 cash crops, 4 vegetables, 4 fruits and 5 ornamentals) were investigated under multiple NH4:NO3 proportions, N rates, pH levels and soilless growing media. All these factors significantly influenced growth and physiological parameters of selected genotypes. Moreover, growth and productivity were significantly superior in exclusive NO3 (100%) nutrition than 100% NH4. Majority of genotypes had optimal performance at pH 5.5-5.8 and N-rate of 7.5 mM. Moreover, N forms were more influential than N rates. In addition, sensitiveness to NH4 varied with genotypes and growing medium. In solution culture, 10% NH4 significantly reduced growth and developed NH4 stress. Stunted growth, reduced biomass and leaf area, foliage chlorosis, necrosis, abscission, and modification of root morphology were the symptoms of NH4 stress. Even though, biomass was reduced, foliage symptoms and root morphology modification did not occur @ 20% NH4 in hybrid culture (peatlite and solution). Similarly, in peatlite, 50-75% NH4 did not substantially reduced growth. Our findings suggest that N forms and their relative proportions are genotype-specific and varies with growing medium. Moreover, optimal NH4:NO3 proportion would improve crop NUE and enhance precision in nitrogen management and sustainability of cropping system.

Subject Area

Plant sciences|Horticulture|Soil sciences

Recommended Citation

Sunil Gurung, "Decoding the Impact of Nitrogen Forms on Plant Growth in Soilless Culture" (2024). ETD Collection for Tennessee State University. Paper AAI31140597.