Cherry tomato (Lycopersicon esculentum Mill.) seeds harvested from fruits at four stages of development [2, 4, 6 and 8 weeks after flowering (WAF)] were washed (1% HCl) and germinated after 72 h of desiccation at 20°C, and 76%, 49% or 12% RH. Seed α-amylase activity was determined at each stage of development and correlated with seed germination. Desiccation at 76% and 49% RH had no significant effect on the germination of seeds at 4, 6 and 8 WAF, whereas it improved germination of seeds at 2 WAF. Low RH (12%) significantly reduced seed germination at all stages of development. There was a positive correlation (r = 0.68, P ≤ 0.05) between germination and α-amylase activity during seed development. Scanning electron microscopy also revealed a correlation between starch grain occurrence in the endosperm and α-amylase activity. Placenta water potential decreased with fruit and seed maturation, and correlated negatively with improved seed germination and α-amylase activity. Promotion of seed germination by desiccation in developing cherry tomato seeds was lost 4 weeks prior to mass maturity (80 ± 3% seed water content and –2.3 ± 0.1 MPa placenta water potential). It is proposed that the water potential differential between the placenta and the seeds influences α-amylase activity and germination behaviour during development.
Mathematical modelling of the osmotic dehydration of cherry tomato (Lycopersicon esculentum var. cerasiforme)