Effects of temperature on photosynthesis and plant growth in the assimilation shoots of a rose

The effects of temperature on photosynthesis, ribulose-bisphosphate carboxylase (Rubisco) content and whole plant growth were investigated in the assimilation shoots of a rose (Rosa hybrida L.). Assimilation shoots were grown at two different day/night temperature regimes of 20/15°C (LT) and 30/25°C (HT) for 42 days after 1-month growth. Although LT initially suppressed the photosynthetic rate during the first 7 days, prolonged growth at LT enhanced potential photosynthesis. This was associated with increases in Rubisco and N contents at the level of a single leaf. Rubisco content and the photosynthetic rate at 25°C were 2.8-fold and 1.6-fold higher in the LT plants than in the HT plants at day 42, respectively. The relative growth rate at the level of the whole plant was lower in the LT plants during the first 28 days and the leaf area ratio was smaller in the LT plants throughout the experiment. However, enhanced photosynthesis during growth at LT led to increases in the net assimilation rate at the level of the whole plant, and final biomass at day 42 did not differ between the two temperature treatments. To enhance the photosynthetic capacity in assimilation shoots of a rose, cultivation at 20/15°C is better than cultivation at 30/25°C.