Chapter 2 32 2.2.2 Stem elongates in response to FR in M82 and Moneymaker Based on the seedling experiment, we chose to focus on shoot responses, with the intention of expanding our research to encompass tomatoes that were bred for two distinct cultivation systems, M82 and Moneymaker (MM). We wanted to conduct phenotyping on young plants to investigate more aspects of stem and leaf responses and zoom in also at the cellular level. We transplanted germinated seedlings into soil and let them recover for a week before 7-day light treatments (WL+FR or WL). We collected phenotypic data of MM and M82 at 21 dag (see Figure 2.3). In general, the stems elongated more and leaves were paler green in both cultivars when they were grown in WL+FR light as compared to WL. Figure 2.3. Comparison of S. lycopersicum cultivars M82 and Moneymaker 24-day-old young plants in WL (left) vs FR+WL (right). This picture was taken at 10 days of treatment to illustrate the different phenotypes between WL and FR+WL. We conducted shoot architecture phenotyping which included measuring the following traits: stem length, hypocotyl length, internode lengths, stem diameters, petiole lengths, rachis lengths, and leaf areas. Length and diameter measurements were taken by caliper and measured traits are shown in Figure 2.4. Leaf area was measured from scanned images using ImageJ. The major finding from the phenotyping is that FR significantly enhances stem and internode length in both varieties (Figure 2.5).
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