Interaction effects of temperature and light on shoot architecture, growth dynamics and gas exchange of young Vitis vinifera cv. Shiraz vines in controlled environment conditions

To examine the interactive effect of temperature and photon flux density (PFD) on growth dynamics and gas exchange of young Vitis vinifera L. cv. Shiraz vines, a controlled environment study was conducted by exposing vines to two different temperatures combined with either high or low PFD. Shoot growth was accelerated and the phyllochron of Shiraz leaves was hastened in the low temperature (25/12°C) x low PFD condition (350 μmol m-2 s-1). In early emerging leaves, leaf area was responsive to temperature whereas in later emerging leaves it was dependent on light intensity. The high temperature (32/20°C) x high PFD (700 μmol m-2 s-1) treatment delayed internode extension of early emerging internodes. However, low temperature x high PFD increased leaf gas exchange across the different growth stages. The net shoot carbon balance was greater for the low temperature x high PFD treatment. Dry matter accumulation was also greater in early emerging internodes irrespective of treatment. These results on young Shiraz vines indicate that 25°C is favourable to 32°C, and some growth characteristics are accelerated at low PFD while others favour higher PFD.