Growth and development of tomato seedlings in substrates containing distinct amendments of a novel calcium montmorillonite nanocomposite hydrogel.

Abstract

Several results demonstrate that the correct use of hydrogels in adequate situations can increase seedling survival rates, plant growth and water-retention capacity of the soil. A technique of producing a nanocomposite hydrogel using calcium montmorillonite (NC-MMt) was recently developed. However, research results are still necessary in order to validate this innovative hydrogel, particularly for the production of vegetable crop transplants. In this context, the main objective of the present study was to evaluate the growth and development of ‘BRS Nagai’ tomato seedlings in substrates containing different amendments of NC-MMt. The trial was conducted in a 3 x 3 factorial design, with three replications. The substrates (peat moss – T1, pine bark – T2, and coconut peat based – T3) represented the first factor and three rates of hydrogel NC-MMt (0% – R1, 1.5% – R2 and 2.0% – R3, on a w/w basis) represented the the second factor. Each plot was composed of 16 plants that were compared after three weeks in all the treatments. Root diameter (means of 2.40 mm²), number of leaves (means of 12 leaves per plant), and plant emergency percentage – PEP (means of 86.8% at seven days after sowing – DAS) did not differ significantly amongst all factors. PEP at 14 DAS, plant height, plant height/shoot dry weight ratio, root dry weight, shoot dry weight/root dry weight ratio, leaf area, and Dickinson quality index were responsive to substrates, mainly T1. Root superficial area (RSA) and root volume (RV) were significantly affected by the distinct rates of NC-MMt. Treatments R2 (1.5%) and R3 (2.0%) differ significantly compared to control – R1 (0%). Positive responses for two factors (T1 substrate; R2 and R3 NC-MMt rates) were achieved for stem diameter (SD), RSA, RV values. In addition, no phytotoxic effects were observed. Therefore, tomato seedlings of the cultivar ‘BRS Nagai’ can be efficiently produced by means of one of these combinations.