The Journal of Agricultural Science




CROPS AND SOILS

Cotton responses to different light–temperature regimes


D. ROUSSOPOULOS a1, A. LIAKATAS a2c1 and W. J. WHITTINGTON a3
a1 Hellenic Cotton Board, 150 Sygrou Ave, GR-176 71, Athens, Greece
a2 Agricultural University of Athens, Department of Land Reclamation and Agricultural Engineering, 75 Iera Odos, GR-118 55, Athens, Greece
a3 University of Nottingham, School of Biological Sciences, Sutton Bonington Campus, Loughborough, Leics LE12 5RD, UK

Abstract

A series of experiments investigating the interactive effects of light and temperature on vegetative growth, earliness, fruiting, yield and fibre properties in three cultivars of cotton, was undertaken in growth rooms. Two constant day/night temperature regimes with a difference of 4 °C (30/20 and 26/16·5 °C) were used throughout the growing season in combination with two light intensities (75 and 52·5 W m−2).

The results showed that significant interactions occurred for most of the characters studied. Although the development of leaf area was mainly temperature-dependent, plants at harvest had a larger leaf area when high temperature was combined with low rather than with high light intensity. Leaf area was least in the low temperature–low light regime. However, the plants grown under the high temperature–low light combination weighed the least.

Variations in the number of nodes and internode length were largely dependent on temperature rather than light. Light did, however, affect the numbers of branches, sympodia and monopodia. The first two of these were highest in the high light–high temperature regime and the third in the low light–low temperature regime.

All other characters, except time to certain developmental stages and fibre length, were reduced at the lower light intensity. Variation in temperature modified the light effect and vice versa, in a character-dependent manner. More specifically, square and boll dry weights, as well as seed cotton yield per plant, were highest in high light combined with low temperature, where the most and heaviest bolls were produced. But flower production was favoured by high light and high temperature, suggesting increased boll retention at low temperature, especially when combined with low light. Low temperature and high light also maximized lint percentage.

Fibres were shortest in the high temperature–high light regime, where fibre strength, micronaire index and maturity ratio were at a maximum. However, the finest and the most uniform fibres were produced when high light was combined with low temperature.

Cultivar differences were significant mainly in leaf area and dry matter production at flowering.

(Received February 3 1998)


Correspondence:
c1 To whom all correspondence should be addressed. Email: lhyd4als@auadec.aua.ariadne-t.gr


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