Rose Quality as Affected by Higher Air Temperatures Resulting from Poly-Tunnel Height in a Subtropical Region

Abstract

Highlights Interior temperatures increased with decreasing poly-tunnel height. In subtropical regions, high interior temperatures of poly-tunnels could degrade quality of rose-cut flower. Stunted growth of rose plants because of higher temperatures could lead to mis-interpretations of nutrient deficiency. Abstract . High temperature is a major constraint to plant production in many regions of the world. Observations indicate that poly-tunnel structure design can influence interior temperature, and in turn determine the quality of cut flowers, including the length of the stems, the leaf biomass, and nutrient uptake. In this study, interior temperature and cut-flower quality of roses were assessed in five poly-tunnels with eave heights ranging from 2 to 4 m. Interior temperatures from 11:00-15:00 h in the hottest months of July and August were monitored. Rose (Rosa hybrida ‘Peach Avalanche’) was cultivated in these poly-tunnels with the same cultivation regimes. Higher interior temperatures were observed in poly-tunnels with lower eave heights. Leaf membrane thermal stability (MTS) values were negatively correlated with higher interior temperatures, indicating that the photosynthetic system of plant leaves was impaired. Stem length and mass were decreased with higher temperature by over 50%, while leaf biomass decreased by 25% in the poly-tunnel with eave height of 2 m in comparison with that of 4 m. Nitrogen concentration in plant leaves increased with higher temperature, whereas the patterns of other elements were not associated with different poly-tunnel eave heights. These results indicate that poly-tunnel interior high temperatures that were associated with lower eave heights are a major constraint for commercialized rose-cut flower production in this region, and improved design of poly-tunnels could increase production. Keywords: Cut flower, Membrane thermal stability, Stem length, Stem mass, Yunnan Province.