Differences of Morphological Characteristics between Japanese Tomato ‘CF Momotaro York’ and Dutch Tomato ‘Endeavour’ with Single-truss Tomato Plants Grown at High Density

Dutch tomato cultivars have been bred with an emphasis on yield (Higashide and Huevelink, 2009) on the premise of long-term and high-wire system (hereinafter referred to as Dutch cultivation system). Many studies have compared the characteristics of Japanese and Dutch cultivars in order to clarify the factors of high yield (Matsuda et al., 2011a; 2011b; 2013; Kakita et al., 2015). The main reasons for the high yield of Dutch cultivars are low light extinction coefficient and high photosynthesis rate, resulting in high light utilization efficiency (Higashide and Huevelink, 2009). On the other hand, Japanese tomato cultivars have been bred with an emphasis on quality rather than yield (Higashide and Huevelink, 2009), and the selection environments for tomato cultivars differ greatly between Japan and the Netherlands. Japanese cultivars have been selected in open fields subjected to water stress, whereas Dutch cultivars have been selected in a hydroponic condition. In addition, the cultivation method mainly focuses on relatively short plant heights, such as picking meristem in 6 to 8 stages and performed twice a year, or continuous pinching cultivation. In recent years, low-node and high planting density system has attracted attention as a distinctive Japanese cultivation system for stable production of highquality tomatoes (Johkan et al., 2013;2014; Kinoshita et al., 2014; Tewolde et al., 2016). Therefore, in order to clarify the varietal characteristics of Japan and the Netherlands, it is necessary to compare those cultivars in the context of the cultivation methods in Japan and the Netherlands. In this experiment, we focused on morphological characteristics of both Japanese and Dutch cultivars. The morphological difference between Japanese and Dutch cultivars in Dutch cultivation system has been already discussed in detail (Higashide, 2018). However, there is limited information on the morphological characteristics of both cultivars in low-node and high density planting system for high-quality fruit production. In low-node and high-density planting system, the light condition in the community tends to deteriorate due to a decrease in the amount of light transmitted to lower areas caused by the 4― 5 times higher planting density compared with that in the Dutch cultivation system. As a solution to this problem, there are some reports of improvement in the training method and supplemental light within the community (Lu et al., 2012a; 2012b; Johkan et al., 2013), but these were performed using only Japanese tomato cultivars. Therefore, the purpose of this study was to clarify the differences of Japanese and Dutch cultivars by focusing on the morphological characteristics and search for suitable morphological features for the Japanese-style cultivation. In order to evaluate the difference in morphological characteristics, we use ‘CF Momotaro York’ as Japanese cultivar, and ‘Endeavour’ as Dutch cultivar. These cultivars are cultivated widely in their respective country.