The effect of total available photosynthetic photon flux on single truss tomato growth and production

SummaryThe yield of tomato, Lycopersicon esculentum Mill. cv. Dombito, was compared under both supplemental high pressure sodium (HPS) lighting and natural greenhouse light conditions. HPS light (100 μ moles m−2s−1) was supplied over 18 hours daily (0400 to 2200 hours). All comparisons were made under single truss cropping conditions. A strong positive correlation (r=0.947) was observed between the total yield and total photosynthetic photon flux (PPF) received in the period from anthesis to harvest. Total PPF in the seedling stage (emergence to anthesis) was strongly correlated (r=−0.867) with timing of anthesis. Furthermore, changes in the leaf area ratio (LAR), specific leaf weight (SLW) and the relative growth rate (RGR) indicated that HPS lighting increased the rate of tomato seedling development without altering the basic pattern of development. The relationships, identified in this study, defining crop timing and crop yield represent the basis of a planning model that can be used for crop simulation and economic evaluation of the single truss system.