Previous work has suggested that a very dense cotton (Gossypium hirsutum L.) population may be superior to the conventional one, especially in marginal regions for cotton production, like Greece. Three population densities (100, 50, and 25 cm between rows with 10 cm within row spacing), three planting dates in 1974 and two in 1975, and three varieties were used in an experiment carried out at Sindos, Greece, to investigate the effect of the above factors on growth and development of cotton.
Planting date and density differentiated growth and development greatly. The influence of planting date was strongest on earliness, while density affected most morphological characteristics and yield components. Early sowing overcame the effect of reduced and prolonged seedling emergence, produced earliness and increased yield, particularly in the shorter growing season of 1974. Late planting dates were inferior in flowering rate, maturation rate index, flower and boll number, boll weight, yield, lint percentage, and Micronaire index.
Increasing density reduced individual plant growth and productivity. However, in per unit land area, there was higher total dry matter production, earlier and more abundant foliage and fruiting, but not a proportional increase of economic yield and earliness. The very dense plants showed lower efficiency of leaves, higher fruit shedding, and smaller boll size. Medium density compared to high density was more consistent in earliness and high yield.
No significant interaction between density and planting date was found for yield. Considering earliness, the superiority of high densities was reduced under late planting. The relative performance of the three cultivan was not substantially affected by population density and planting date.