The effect of nitrogen fertilization rate on growth and physiological parameters of three purslane genotypes grown in a soilless cultivation system

Abstract

Purslane (Portulaca olearacea L.) is a wild edible species, while it is also considered a troublesome weed throughout the world. The present work evaluated the effect of different nitrogen application rates (0, 200, 400 and 600 ppm of total nitrogen) on growth (plant height, fresh weight of leaves and shoots, total leaf area) and physiological parameters (SPAD index, photosynthetically active radiation (PAR)) of three purslane genotypes, namely 'Domokos', 'Common Purslane' and 'Purslane'. Seeds were directly sown (October 9, 2019) in 2-L pots containing peat: Perlite (2:1, v/v) and were harvested 37 days after sowing (DAS; November 14, 2019). Plant height increased up to the rate of 400 ppm for genotype 'Domokos', while for 'Common Purslane' and 'Purslane' genotypes it further increased for the rate of 600 ppm without being significantly different from the rate of 400 ppm. Moreover, 'Purslane' plants were significantly higher from the other two genotypes for all the tested rates, except for the control treatment where no differences between the 'Common Purslane' and 'Purslane' genotypes were observed. SPAD indices showed increasing trends when nitrogen rates increased, while the lowest values were recorded for the control treatment, regardless of the genotype. PAR activity values showed fluctuating trends depending on the genotype and the nitrogen application rate, while total leaf area increased when the higher application rates (400 and 600 ppm) were applied. Fresh weight of leaves and shoots was significantly increased with increasing nitrogen rates for all the studied genotypes, especially for genotype 'Common Purslane' at the 600 ppm rate. In conclusion, nitrogen fertilization beneficially affected the tested plant growth and physiological parameters in a genotype dependent manner. However, further studies are needed to evaluate nitrogen effect on quality parameters such as nitrates, oxalic acid and omega-3 fatty acids content. © 2021 International Society for Horticultural Science. All rights reserved.