ASSESSMENT OF TOMATO SEEDLING SUBSTRATE-ROOT QUALITY USING X-RAY COMPUTED TOMOGRAPHY AND SCANNING ELECTRON MICROSCOPY

The study proposed to use X-ray computed tomography (X-ray CT) alongside destructive method for assessing tomato seedling soil substrate and agronomic properties and scanning electron microscopy (SEM) for substrate-root elemental composition analysis. Three growth media having sphagnum peat moss, perlite, and vermiculite were mixed in percentage proportions of 60:20:20, 60:40:0, and 60:0:40 for substrate 1 (S1), substrate 2 (S2), and substrate 3 (S3), respectively. Results from the X-ray CT showed mean range of porosity for S1, S2, and S3 as 17.8% to 24.7%, 40% to 52.8%, and 11.3% to 14.2%, respectively. Finite element simulation performed on the X-ray CT scans also showed the maximum von-Mises stress distribution and stiffness to be greater in S1 followed by S2 and S3. Using the destructive method for measuring agronomic properties indicated that increasing bulk densities (0.28, 0.32, and 0.36 gcm(-3)) negatively affected root length in S2 and S3. Also, at 0.28 gcm-3, the highest root volume especially in S1 and S2 were recorded. Lastly, SEM-EDS analysis indicated that O, Si, N, P, K, Fe, and Mg present were significantly greater in S1 than S2 and S3. In all, the study suggests that the composition of sphagnum peat, perlite, and vermiculite in the proportion of 60:20:20 produces quality tomato seedlings.