Abstract
Increasing the plant population of tomatoes (Lycopersicon esculentum cvs 'Floradel' and 'Vendor') from 24601 to 35879 plants per hectare reduced yield by 0·43 kg per plant averaged over the mulch variables but this resulted in 25609kg/ha more tomatoes at the high population. The highest yield (120000 kg/ha) was obtained by using a clear polyethylene mulch at a population of 35879 plants per hectare, while the lowest yield (80000kg/ha) resulted from no mulch at 24601 plants per hectare. Under low light condition (160g cal/cm2/day) the oil temperature (5cm deep) under the clear polyethylene mulch was 3° higher than that under aluminium foil or with no mulch, but under high light (344g al/cm2/day) the soil temperature under clear polyethylene was 5° warmer than with no mulch and 11º warmer than under aluminium foil. Plants with an aluminium foil mulch were exposed to 9, 9 and 8 per cent more blue, red and far red light, respectively, under sunny conditions but 19 13 and 23 per cent more light, respectively, under cloudy conditions than plants with no mulch or a clear polyethylene mulch.
