Concentration and composition of nutrient solution affect root formation of young tomato
2003
Schwarz, D.
Young roots and especially the root hair zone are most important for nutrient uptake. However, these parts are also most sensitive to salinity, one of the main problems in controlling closed soilless culture systems today. Supply of nutrient solution with constant concentration may increase electrical conductivity (EC) in the root environment up to 10 dS.m-1. There, also an enrichment of ions, such as sodium, chloride, or sulphate, is typical. Hence, investigations were carried out to monitor and quantify root damage and formation by different composition and concentration of the nutrient solution. Three tomato plants at 2-leaf-stage (Lycopersicon esculentum [Mill] L. cv. Counter) were transferred to a 2 l container filled with aerated nutrient solution. Tomato plants grew in climate chambers for 14 days (16 h light, 600 μmol.m-2s-1, 25/20°C day/night). The basic nutrient solution of 1.5 dS.m-1 was supplemented with either NaCl or macronutrients to give an EC of 1.5, 5 and 9 dS.m-1. Fresh and dry mass of shoots and roots, total root length, number of adventitious roots and of all tap root laterals decreased with increasing nutrient solution EC. Dry matter content of roots and tap root diameter were not influenced while shoot dry matter content increased with increasing EC. NaCl enhanced root fresh matter, tap root diameter, total root length and number of adventitious roots compared with the macronutrient treatment. On the contrary, NaCl reduced shoot dry matter content and number of all laterals. Results confirm that attempts to extrapolate results obtained on average root systems to single root formation could be misleading.
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