Influence of day and night temperature on the growth of young tomato plants
ABSTRACT Young tomato plants were grown at different day and night temperature combinations with an average of 21°C. Some combinations with a different average 24-h temperature were included. Day temperature (Td) varied between 16 and 26°C, night temperature (Tn) between 12 and 26°C, while the daylength was 12h. Light intensity was about 26 W m−2 photosynthetic active radiation (PAR).An inversed temperature regime (Td lower than Tn) reduced plant growth (fresh weight, FW; dry weight, DW) and development (number of leaves, number of trusses). Reduction in development was less than reduction in growth. Growth reduction was caused by a lowering of the leaf area ratio (LAR). The decrease in LAR at an inversed temperature regime was caused mainly by a decrease in specific leaf area (SLA). Net assimilation rate (NAR) was not influenced by the temperature regime. For young widely spaced plants a lower SLA (thicker leaves) results in less light interception and thus in growth reduction.It is possible now to explain the different reactions on temperature regime at the same temperature intergral between young plants and closed canopies. In a closed canopy (a producing crop) differences in leaf area index, brought about by differences in leaf thickness, have hardly any influence on light interception because most light has been already intercepted anyway. This explains why a producing crop, in contrast to young plants, shows hardly any reaction to temperature regime at the same temperature integral.A regression analysis indicated that for FW and DW, plant length, leaf area (A), number of leaves, number of trusses, relative growth rate (RGR), LAR and SLA, Td is more important than Tn.
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ABSTRACT: Active gibberellin (GA(1)) is an important mediator of thermoperiodic growth in pea. Plants grown under lower day than night temperature (negative DIF) elongate less and have reduced levels of GA(1) compared with plants grown at higher day than night temperature (positive DIF). By comparing the wild type (WT) and the elongated DELLA mutant la cry(s), this study has examined the effect of impaired GA signalling on thermoperiodic growth, photosynthesis, and respiration in pea. In the WT a negative DIF treatment reduced stem mass ratio and increased both root mass ratio and leaf mass ratio (dry weight of specific tissue related to total plant dry weight). Leaf, root and stem mass ratios of la cry(s) were not affected by DIF. Under negative DIF, specific leaf area (projected leaf area per unit leaf dry mass), biomass, and chlorophyll content of WT and la cry(s) plants were reduced. Young, expanding leaves of plants grown under negative DIF had reduced leaf area-based photosynthetic capacity. However, the highest photosynthetic electron transport rate was found in fully expanded leaves of WT plants grown under negative DIF. Negative DIF increased night respiration and was similar for both genotypes. It is concluded that GA signalling is not a major determinant of leaf area-based photosynthesis or respiration and that reduced dry weight of plants grown under negative DIF is caused by a GA-mediated reduction of photosynthetic stem and leaf tissue, reduced photosynthesis of young, expanding leaves, and reduced growth caused by low temperature in the photoperiod.Journal of Experimental Botany 01/2010; 61(4):1015-29. · 5.24 Impact Factor
- Acta horticulturae 01/2011; 907:163-168.
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ABSTRACT: Expansion growth is limited if the difference between day and night temperature (DIF) is negative. Growth is also limited high salinity. Expansion growth of tomato seedlings was studied under day/night temperatures of 16/24°C and 24/16°C, and nutrient solution salinities of 3 and 15 mS cm-1 to ascertain whether interactions exist between the two stress forms. Water status was also studied in order to assess possible mechanisms of growth retardation. A significant interaction between DIF and salinity was found for all recorded growth variables. Hypocotyl length, plant height, leaf area and fresh and dry weight were lower at negative DIF than at positive, the reduction being greater at low salinity than at high. Increased salinity also reduced growth, more so at positive DIF than at negative. Growth reduction at negative DIF was accompanied increased shoot water and osmotic potentials. Pressure potential was unaffected DIF. Growth reduction at high salinity was accompanied reduced water and osmotic potentials. Pre-dawn pressure potential was increased at high salinity, whereas no effect of salinity on pressure potential at midday was found. The differences in effects on water status between the two stress forms may suggest differing mechanisms of growth retardation.Annals of Applied Biology 02/2008; 127(1):191 - 200. · 2.15 Impact Factor