Crescimento, estado nutricional e fotossíntese de Cedrela odorata L. adubada com diferentes proporções de Nitrato e Amônio

Abstract

Nitrate (N-NO3-) and ammonium (N-NH4+) are the main forms of nitrogen (N) absorbed by plants and that can affect differently the nutritional status, growth and photosynthetic aspects of different species. We tested whether different proportions of N-NO3- and N-NH4+ influence the nutritional, photosynthetic and growth parameters in Cedrela odorata seedlings. We observed that this specie is responsive to nitrogen nutrition; however, it is little influenced by the proportions of the tested forms. The use of the proportion of 40% N-NO3- and 60% N-NH4+ demonstrates a beneficial or biostimulating effect on the species, since the nutritional, photosynthetic and growth parameters are only slightly influenced by the forms of N. We conclude that this specie requires N in the initial phase of cultivation, and that can be provided either as ammonium or nitrate. These findings were confirmed when seedlings of Cedrela odorata were cultivated for 150 days in the greenhouse, under the effect of 200 mg dm-3, using six different proportions of N-NO3-: N-NH4+ (100: 0, 80: 20, 60:40, 40:60, 20:80 and 0: 100%, respectively), plus a control treatment without the supply of N.