Temperature effect on growth and development indices in uniform and heterogeneous red clover canopies

The aim of this study was to assess the temperature effect on growth and development parameters in uniform (pure culture) and heterogeneous (grass-clover mixture) red clover canopies with or without foliar fertilization in the most productive year of red clover. The relationships between biological efficiency (εb), Leaf Area Index (LAI), canopy height growth (Hts), light environment (PAR) and temperature in uniform and mixed canopies for both clover ploidy groups are presented. The temperature effect on red clover LAI corresponded to a non-linear sigmoid function. The second foliar fertilizer application had a major effect on leaf area development in uniform canopies. Both ploidy groups had a similar LAI growth trend and favorable responses to foliar fertilization. The correlation between leaf area growth and temperature was statistically significant (p<0.05) for red clover cultivars in the unfertilized grass-clover mixtures. The hybrid ryegrass showed higher regression coefficients in tetraploid clover mixtures (p<0.01). Foliar fertilization determined the smoothing of species behaviors to the temperature regime meaning that the differences between diploids and tetraploids, and between hybrid ryegrass from both variants were less visible.