Plant spacing effects on growth and development of the greenhouse tomato

Abstract

The effect of six equidistant spacings (23, 30, 38, 45, 53 and 60 cm, corresponding to 113 000, 74 000, 53 000, 40 000, 31 000 and 25 000 plants ha−1, respectively) on growth and development of greenhouse tomato (Lycopersicon esculentum Mill. 'Jumbo' and 'Ohio CR-6') was studied over two fall and one spring seasons. A consistent increase in plant height and intermode length with closer plant spacing and an apparent trend for taller plants and longer intemodes in the inside of four-row canopies compared to outside were found in both spring and fall seasons. Plant development, as evidenced by the rate of flower cluster development, was affected adversely only when plant spacing was less than 45 cm. Leaf area decreased steadily at all reductions in plant spacing (faster in inside than outside plants) in the fall, but in the spring it attained a maximum value at the intermediate spacing of 45 cm. The fruit set rate of both cultivars was not affected by plant spacing in the fall except under extreme shading conditions (23-cm spacing) while it declined steeply in the spring with decreasing plant spacing. Results suggest a shorter supply of carbohydrates in the spring, compared to the fall, which is attributed to a more intense competition for light in the spring than the fall and this is likely to result in higher productivity in the fall than in the spring when plants are closely spaced. Key words: Lycopersicon esculentum, plant height, fruit set, LAI