Stem elongation and leaf orientation in Lilium longiflorum Thunb. were influenced more by the difference (DIF) between day temperature (DT) and night temperature (NT) than absolute DT or NT from 14 to 30 C. Plant height and internode length increased 129 and 382%, respectively, as DIF (DT‐NT) increased from –16 to 16 C as compared to only 15 and 58% when either DT or NT was increased from 14 to 30 C, respectively. Leaf orientation, defined as the angle between a line perpendicular to the stem and the line from the leaf base to the leaf tip, increased 43° (leaves became more upright) as DIF increased from –16 to 16 C. In contrast to plant height, internode length, and leaf orientation, leaf and flower length were influenced more by absolute temperature than DIF. Leaf and flower length decreased 32 and 14%, respectively, as NT increased from 14 to 30 C. DT had little effect on either leaf or flower length. The influence of DIF on stem elongation suggested that thermomorphogenesis was not a function of total plant carbohydrate or carbohydrate translocation. Instead, DIF appeared to influence the endogenous gibberellin content or the response of plant tissue to gibberellin. Similarities between thermomorphogenic plant responses and photomorphogenic plant responses suggested that these two processes may be related with respect to their perception and/or transduction.
A high tunnel environment was evaluated for production of leaf (`Two Star') and romaine (`Parris Island Cos') lettuce (Lactuca sativa) in a northern location (lat. 64°49'N). Ten plantings were made 1 week apart from May to August. Averaged over the season, the air temperature was 1.5 °C and the soil 0.8 °C higher in the high tunnel than the field. `Two Star' planted on 3 Aug. and harvested on 16 Sept. produced higher yield (P < 0.001) in the tunnel. Head weight was 195 ± 12 g in the tunnel and 99 ± 8 g in the field. For the 13 July-planted `Two Star' lettuce, the field produced significantly (P < 0.001) more at 202 ± 21 g/head than the 135 ± 29 g/head in the tunnel. The three consecutive field plantings of 1, 8, and 15 June resulted in higher `Parris Island Cos' yields than corresponding plantings in the high tunnel. Head weights for harvests on 11, 18, and 25 July were 457 ± 60, 476 ± 65, and 478 ± 25 g under field conditions and 354 ± 46, 331 ± 52, and 312 ± 14 g in the high tunnel. `Two Star' was observed less prone to bolting than `Parris Island Cos'. Although a high tunnel did not generally support increased productivity in this study, the added protection resulted in high quality lettuce with limited necessary preparation and marketing loss in comparison to the field-grown lettuce.
. Chrysanthemum dry matter partitioning patterns along irradiance and temperature gradients. pan.^J. Plant Sci. 72: 307 316. The influence of photosynthetic photon flux (PPF,.6 mol d -' m -') and day (DT) and night (NT) temperature (10-30'C) on dry matter accumulation and partitioning was studied in Chrysanthemum morifolium Ramat. 'Bright Golden Anne'. Total plant dry matter varied from 3.6 to 17.2 g at flowering. Plants with the greatest dry matter were from treatments with high PPF levels and temperatures. Accumulation of dry matter in roots, stems, leaves and flowers examined on a normalized time and normalized dry matter basis showed similar trends independent of DT, NT and PPF during development. Accumulated dry matter in roots, stems and leaves increased to a maximum and then decreased as the flowers were developing.Maximum leaf, root and stem dry matter was reached at 81, 85 and9l%, respectively, of required time from staft of short days (SD) to flower. Proportion root dry matter increased and proportion leaf dry matter decreased in the plants as PPF
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.