Relation between nitrogen source and plant growth regulators on tomato growth and nutrient uptake

Abstract

Tomato plants (Lycopersicon esculentum L.) were grown in sand culture with NH₄⁺ or NO₃^- sources of N and four plant growth regulators (Cytokinine (CK), Trycotanol (TCOT), ABA (Abscisic acid) and Cycocel (CCC)). In general, the plant growth regulators had no significant effect on tomato growth except CCC which reduced dry weight in plants supplied with NO₃^-. Ammonium reduced plant growth as compared to NO₃^-, for all treatments but CCC. The cations K, Ca and Mg content in tissue decreased with NH₄⁺ treatment as compared to NO₃^-. However Trycotanol tended to reduce this effect by increasing Ca in plants. CCC enhanced nitrate content in plant shoot supplied with NO₃^-, but had no effect on plants supplied with NH₄⁺. Every plant growth regulator increased free NH₄⁺ in plant shoots supplied with that N source.