Environmental effects on linseed (Linum usitatissimum L.) yield and growthof flax at different stand densities

The effect of environmental factors and stand density on linseed (Linum usi tatissimum L.) yield was investigated by examining yield components and dev elopment rates from 4 years of held experiments carried out at Viterbo, Cen tral Italy, in which different seed rates were tested. Spring sowings were carried out using the linseed cultivar 'Mikael'. Growth analysis using the functional approach and modelling using the SUCROS model for potential prod uction parameterized for linseed were used to carry out a more detailed ana lysis of environmental effects. Linseed yields varied greatly in response to weather and soil type but show ed very little effect of plant density. The crop was able to compensate for reduced stand densities mainly by increasing the number of capsules per pl ant. All yield components were significantly influenced by weather as repre sented by the year of sowing. Growth analysis showed that the unit leaf rat e had higher values at lower stand densities, suggesting that self-shading at higher densities decreased the efficiency of the foliage. The environmen tal factors most likely to affect yields were high temperature, due to its effect on development rate, and the consequent shortening of the growing cy cle and perhaps water shortage. The foliage duration was more important tha n the maximum leaf area index. (C) 1999 Elsevier Science B.V. All rights re served.