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: Chilling tolerance is a desirable trait in commercial tomato varieties, in order to extend the growing season and geographic range. Two Nearly Isogenic Lines (NILs) with introgressions in chromosome 2 and 3 of Solanum habrochaites S. Knapp & D.M. Spooner, a cold-resistant wild tomato, were evaluated in the field. Four plantings were established between 21 August and 2 October 2006 (day 232 and 274). Throughout the experiment the heat sum was interpreted using air temperature to calculate growing degree days (base 12 °C) and chilling hours (below 12 °C), with the daily light integral calculated as global solar radiation. The relative post-transplant growth rate, fruit set and yield, were evaluated over two successive 10-d periods. Chilling tolerance is expressed under high radiation and low temperature conditions, which occurred during the 10-d post-transplant evaluation period beginning on day 257, when both NILs achieved a leaf area growth rate 1.7 times higher than the control plants. During the second evaluation period, 10-20 d post-transplant, both NILs grew on average, 1.4 times more than the control. There were no significant differences in earliness or fruit set. These NILs should not be used as a direct source to obtain chilling tolerant varieties, because of the low fruit set, 84% lower in LA3921 than the control, probably due to linkage drag and poor environmental adaptability in both lines.Chilean journal of agricultural research 01/2010; 70:552-558. · 0.45 Impact Factor
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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.