**5. Conclusion**

In the pinching treatments (shoot removal), the growth of lateral shoots, especially in the threetrue-leaf pinching treatment, was greater compared with that in the control (**Table 1**), which would be due to the increase of mineral nutrients uptake since the distribution of some mineral nutrient elements was changed by the pinching treatment. The differences in lateral shoot lengths in the plants by the pinching treatment at four to six true leaves were larger than in the plants by the pinching treatment at zero to three true leaves in the determinate-type tomato "Wase Daruma" [14]. Almost the same result was obtained in regard to the lateral shoot lengths in the different pinching treatments in the present study. The shoot lengths of 3-scaffold shoots by pinching treatment were longer than those of 6-scaffold shoots because the nutrient competition among the remaining shoots reduced in watermelon (*Citrullus lanatus*) [39]. This might be the reason that at 59 DAT the mean lateral shoot lengths in the three-true-leaf pinching treatment were more uniform compared with those in the six-true-leaf pinching treatment. In this study, perhaps the emergence period of AB was shorter and the competition for absorbed mineral nutrients was reduced in the plants that underwent the three-true-leaf pinching treatment. Since the flowering period in the three-true-leaf pinching treatment was significantly shorter than those in the other treatments, the decrease of fruit set ratio that could occur during periods of high air temperatures (over 35°C) might have been avoided by pinching treatment [40]. Although the number of flowers in the three-true-leaf pinching treatment was significantly decreased compared with the other treatments (**Table 2**), there was no difference in the total fruit yield among all the treatments because the fruit set ratio in the three-true-leaf pinching treatment was higher than that in the other treatments. The harvest term in the pinching treatments was shortened until 3 WAH compared with that in the control until 4 WAH (**Figure 7**). These findings are in agreement with those of earlier studies [26, 27, 41]. The possibility for both shortening the harvest term and increasing the early yield was recognized in the threetrue-leaf pinching treatment. In particular, shortening of the harvest term would permit

46 Physical Methods for Stimulation of Plant and Mushroom Development

mechanical harvesting and save labor cost, as described previously [12, 42–44].

The number of flowers per primary lateral shoot was not different in all treatments, whereas the numbers of flowers per secondary and higher lateral shoots in the both pinching treatments were significantly higher compared with that in the control (**Table 2**). The flower numbers on the longer lateral shoots could be increased in processing tomato plants [45]. In eggplants, the flower numbers on pinched plants were higher than those on no pinched plants because the number of lateral shoots would be increased on the former [46]. Therefore, in this experiment, the increases in both the number of flowers and the number of secondary and higher lateral shoots in the both pinching treatments compared with the control might be due to the release of apical dominance

in plants because of the extension of lateral shoots in the previous reports [17, 19, 20, 47].

Pinching (shoot removal) releases apical dominance and removes a metabolic sink in plants [38]. This results in decreased auxin production in the apical bud and increased nutrient distribution into and growth of the lateral shoots [48, 49]. The levels and distribution of N, P, and K were increased in the lateral shoots of bean plants in relation to apical dominance [50]. Ca, a structural component of the cell wall and membranes, is needed for tomato plant growth at early growth stages [51], and its uptake under high-growth conditions was increased in tomato shoots [52, 53]. Fukui et al. [13] also reported that increased the number of flowers were due to the relatively greater availability of photosynthetic products in tomato cultivars In tomato plants, flower bud or shoot removal (pinching treatment) affected the branch formation and fruit yield. The emergence of TFB affected the growth of lateral shoots in indeterminatetype cultivar, whereas it did not affect the growth of lateral shoots in determinate-type cultivar. Therefore, it is suggested that the appropriate management of the lateral shoots would be necessary for improve fruit yield or fruit quality, and it would be different between indeterminate and determinate-type cultivars. In indeterminate-type cultivars, it would be important to consider both the position and timing of shoot pinching and the timing of lateral shoot removal. In determinate-type cultivars, it might be necessary to study the number of lateral shoots or the training direction of the vines in order to avoid plant diseases during the periods of high temperature and/or humidity conditions. The shortening of harvest term and increase of initial fruit production in the three-true-leaf pinching treatment would be due to elongated lateral shoots and shortening of the flowering periods per plant. Thus, the pinching treatment could permit machine harvesting and save labor costs for determinate tomato cultivation. From these results, further studies should be undertaken to elucidate the relationships among shoot growth of plant, number of flowers, and physiological factors such as the sink strength in each organ, the distribution of photosynthetic products, and the changes of nutritional status and some plant growth substances in plants after flower bud or shoot removal (pinching treatment).
