Initial Growth of Rosebay Rhododendron Seedlings as Influenced by Day and Night Temperatures

Abstract

<jats:p>Rosebay rhododendron <jats:italic>(Rhododendron maximum</jats:italic> L.) seedlings were grown in controlled-environment chambers for 14 weeks under long (9-hour) days at 18, 22, 26, or 30C in factorial combination with 15-hour nights at 14, 18, 22, or 26C. Total dry-matter production was lowest for 18C days and highest for 26C days. A similar response occurred for top, leaf, root, and stem dry weights. Nights at 22C maximized total plant, top, leaf, and stem dry weights. The optimum day/night cycle for dry-matter production was 26/22C. Leaf area was optimum with 18C nights. Leaf weight ratio (leaf dry weight: total plant dry weight) increased with an increase in night temperature to a maximum at 22C. Root weight ratio (root dry weight: total plant dry weight) decreased with an increase in night temperature to a minimum at 22C. Stem weight ratio (stem dry weight: total plant dry weight) and shoot: root ratio (top dry weight: root dry weight) were not influenced significantly by day or night temperature. A day/night cycle of 26/22C seems to be optimal for producing-salable plants.</jats:p>

Seedling Growth of Catawba Rhododendron. I. Temperature Optima, Leaf Area, and Dry Weight Distribution

“…Stem weight ratio was fairly constant over thermoperiods (data not presented). Similar responses have been noted for flame azalea (Malek et al, 1992a), mountain laurel (Kalmia latifolia L.) (Malek et al, 1992b), and rosebay rhododendron (Starrett et al, 1993).…”

“…The same response was observed in flame azalea (Malek et al, 1992a). However, Starrett et al (1993) reported that day temperature did not affect specific leaf area of rosebay rhododendron, but nights of 22 and 26C similarly reduced specific leaf area.…”

“…In contrast, Starrett et al (1993) reported no significant day temperature effect on seedling growth of rosebay rhododendron (Rhododendron maximum L.). Leaf area showed a quadratic response with increasing day temperature at all night temperatures except 26C (Fig.…”

“…Our data agree with their report. For rosebay rhododendron, Starrett et al (1993) reported the largest and smallest leaf areas with nights of 18 and 14C, respectively.…”

Plant Physiological, Morphological and Yield-Related Responses to Night Temperature Changes across Different Species and Plant Functional Types

“…Different from the hypothesis proposed by Peng et al (2004) that HNT increased biomass loss by enhancing respiration, our study concluded that HNT increased total biomass but LNT decreased the total, above-ground and below-ground biomass. Total biomass was stimulated by HNT in rice (Cheng et al, 2008, 2009), Ficus insipida and Ochroma pyramidale (Cheesman and Klaus, 2013), Rosebay rhododendron (Starrett et al, 1993), panicum (Patterson, 1990) and soybean (Hewitt et al, 1985). Studies in natural systems have seen impacts on plant phenological development.…”