and Blue Cotyledon MATSUO Kyushu University,

Transcription

1 J. Japan. Soc. Hort. Sci. 41(3) : Studies on the Ecological Horticultural Characteristics Plants of 1. Hypocotyl Elongation Seedlings in and Blue Cotyledon and Red Distortion Lights 1),2),3) of Cucumber Faculty Eisuke of Agriculture, MATSUO Kyushu University, Fukuoka Summary Cucumber seedlings were grown at various intensities of blue and red lights at the constant temperature of 25 C in a phytotron and the hypocotyl length and the distortions in cotyledons were observed. Spring-cucumbers of South Chinese type except `Ochiai' form showed a remarkable distortion and were more sensitive to blue light than other groups in hypocotyl elongation, although their hypocotyl length itself was shorter than other groups'. Summer-cucumbers of South Chinese type showed a slight distortion and their hypocotyl was longer than that of Spring-cucumbers. Summer-cucumbers of North Chinese type except `Sanjaku' cucumbers showed a slight cotyledon distortion and their hypocotyl was longer than that of Spring-cucumbers of South Chinese type. Both summer-, and Spring-cucumbers of Cross-bred type in this experiment showed a slight distortion. They had longer hypocotyl than Spring-cucumbers of South Chinese type and were not so sensitive to blue light in hypocotyl elongation as Springcucumbers of South Chinese type. In `Ao-fushinari' strain belonging to Spring-cucumber of South Chinese type, cultivars of `Ochiai' form showed a slight distortion, although those of `Ao-fushinari' and `Hyuga' forms had a remarkable distortion. `Sanjaku' cucumbers of North Chinese type showed a remarkable distortion. They had a shorter hypocotyl than other cucumbers of that and were sensitive to blue light in hypocotyl elongation as Springcucumbers of South Chinese type. Considered these from the standpoint of cucumber pedigree, it is suggested that cultivars belonging to `Ao-fushinari' and `Hyuga' forms and to `Sanjaku' cucumbers owe their character of remarkable distortion in cotyledon and of sensitiveness to blue light in hypocotyl elongation to `Hanjiro' strain of Spring-cucumbers of South Chinese type. Introduction Cucumber (Cucumis sativus L.), a native of India, has been popular in Japan. According to KUMAZAWA et al. (9,10,11), Japanese cucumbers may be classified into the following 4 1) Contribution from Horticultural Laboratory, Faculty of Agriculture, Kyushu University. 2) This study was supported by the Grant in Aid for Miscellaneous Scientific Research of the Ministry of Education, Japan. 3) Part of this study was presented at the Annual Meeting of the Japanese Society for Horticultural Science, Tsu-shi, Mie Pref., Oct. 10, Received for publication May 24, 1972 ecotypes : 1) South Chinese type : Cucumbers belonging to this type were taken from India to South China via Burma and Indochina and became acclimatized there. They were introduced into Japan more than 1000 years ago. 2) North Chinese type : Cucumbers of this type were brought into North China via the Silk Road and became acclimatized there. These cucumbers were introduced into Japan about 100 years ago and became acclimatized in this country. 3) European type : Cucumbers of this type were brought into Europe from India through Iran and Mediteranean countries. In England, forcing types have been developed markedly. 25(

2 MATSUO : THE ECOLOGICAL CHARACTERISTICS OF HORTICULTURAL PLANTS 251 Table 1. Classification of cucumber cultivars in Japan. Cucumbers belonging to this type were introduced into Japan from U.S.S.R., U.S.A., U. K., etc. about 100 years ago, 4) Crossbred type : Cucumbers of this type have mainly been obtained by crossing of South Chinese type to North Chinese one in Japan. European type cucumbers have been cultured only in a part of Japan, and other 3 types cucumbers have commonly been grown and used for breeding.

3 252 JOURNAL OF THE JAPANESE SOCIETY FOR HORTICULTURAL SCIENCE The recent advance in cucumber growing under structures in Japan has led to the plentiful supply of cucumbers throughout the year. Cucumbers introduced originally into Japan, however, had commonly been cultured and harvested from spring to summer or summer to autumn. Cucumbers for the former growing season are known as Spring-cucumbers and those for the latter as Summercucumbers. Cucumbers of North Chinese type became acclimatized as Summer-cucumbers in this country. They are different from the South Chinese ones in sex expression, root growth, drought resistance, etc. A few of cucumbers of South Chinese type have been cultured as Summer-cucumbers, and many of them of this type as Spring-cucumbers. Crossbred type has both Summer-cucumbers and Spring-ones. According to EsASHI (3,4), light quality is as important as day length and temperature for the northward migration of plants. GATES (8) showed that there is the variation in spectral distribution of solar rays as a function of wave length at different altitudes and at different air masses. The intensities of blue and red lights vary with the latitude, the season and the hour of the day (17). It may be easily presumed that blue and red lights, which act effectively on the photomorphogenesis in plants, would cause not only to change a sex expression but also to elongate seedlings and expand leaves. MINOHARA et al. (16) reported that the cotyledon distortion occurred remarkably in orange and green lights, although the response of cotyledons to these lights varied with different ecotypes. In this experiment, therefore, the author has undertaken an investigation on hypocotyl elongation and distortion in cotyledons at various intensities of blue and red lights. Materials and Methods Cucumber cultivars used in this experiment and the classification of Japanese cucumbers are shown in Table 1. Ten seeds of each cultivar were sown in 10 cm plastic pot filled with sand. Seedlings were grown for 2 weeks under the conditions of 24 hours continuous illumination of blue (B) or red (R) lights at the constant temperature of 25 C in the Phytotron, Kyushu University. Hypocotyl length and cotyledon distortion were examined on 15 th day after seeding. Plants were watered every 5 days with 1:1000 Hyponex solution. Each experiment consisted of 10 cultivars of 2 pots and was repeated twice or more. Cultivar `Sagami -han jiro' was used as control one in each experiment. Mitsubishi Coloured Fluorescent tubes, FL-20-B and FL-20-R, were used as light sources (15). Light intensities of L 1, L2, L 3 and L 4 were 0.020, 0.014, and gcal. cm_z. min-1, respectively. Intensities of blue and red lights corresponded to them, respectively. Results and Discussion 1. Hypocotyl elongation : The coefficient Table 2. Hypocotyl length of cucumbers in blue and red lights.

4 MATSUO : THE ECOLOGICAL CHARACTERISTICS OF HORTICULTURAL PLANTS 253 Table 3. Hypocotyl length and elongation ratio of North Chinese cucumbers. Fig. 1. Elongation ratio of cucumbers at various light intensities. Elongation ratio was presented as the per cent of the hypocotyl length in blue light to that in red one. 0-0 Summercucumber of South Chinese type, - Summer cucumber of Cross-bred type, 0-ED Summer-cucumber of North Chinese type, A----A Spring-cucumber of South Chinese type, A----A Springcucumber of Cross-bred type. of variability(cv) of each cultivar in each experiment was 15% at the maximum and 3 % at the minimum. CV of most cultivars was less than 10%. Both in blue and red lights, there was a tendency that the hypocotyl shortened as the light intensity was stronger. No significant difference was, however, observed in the hypocotyl length between cucumbers of different ecotypes and between the Summer- and Spring-cucumbers. The hypocotyl of Spring-cucumbers of South Chinese type was shorter than that of any other groups both in blue and red lights (Table 2). This difference was remarkable in blue light. The elongation ratios, hypocotyl length in blue light to that in red one, are shown in Fig. 1. In L 1, L2 and L3, the elongation ratio of Spring-cucumbers of South Chinese type was significantly lower than that of any other groups. In L4, however, no difference was observed in the ratio between them. The elongation ratio in Spring-cucumbers of South Chinese type lowered as the light intensity was stronger. No significant difference in the ratios with light intensities was observed on other cucumbers. There was a tendency that the hypocotyl of `San jaku' cucumbers in blue light was shorter than that of any other cultivars belonging to North Chinese type, although there was no significant difference. Their elongation ratios were significantly lower than those of any others (Table 3). The hypocotyl length at lower light intensities was compared with that in B 1 and R 1, respectively (Table 4). There was no significant difference between the groups in red light. In blue light, however, significant difference in the elongation was observed between Spring-cucumbers of South Chinese type and Spring-cucumbers of Cross-bred type or Summer-cucumbers of South Chinese type in B3, and also between Spring-cucumbers of

5 254 JOURNAL OF THE JAPANESE SOCIETY FOR HORTICULTURAL SCIENCE Table 4, of Hypocotyl length at various blue and red lights. intensities South Chinese type and other cucumbers in B4. It has been reported that the hypocotyl length was longer in blue light than in red one at low light intensity and vice versa at high light intensity (14). In this experiment, the elongation ratios, hypocotyl length in blue light to that in red one, in most groups except Spring-cucumbers of South Chinese type were almost the same at any light intensity (Fig. 1 and Table 2), i. e., the hypocotyl length in blue light was almost equal to that in red one. In the Spring-cucumber of South Chinese type, the hypocotyl shortened / and the elongation ratio lowered as the light intensity was stronger. At the lowest light intensity (L4) the hypocotyl in blue light was almost the same as that in red one. The hypocotyl of Spring-cucumbers of South Chinese type was shorter than that of any other groups both in blue and red lights. In B4 it was more than 200 % of that in Bl, although for other groups about 160% (Table 4). Fig, 2. Distortion in cotyledons of cucumber seedling. The distortion was graded as (-), (-a-) and (~f) (from left to right), respectively. It is an important phenomenon that Springcucumber of South Chinese type is highly sensitive to blue light in its hypocotyl elongation as compared with other groups under the experimental conditions. FUJIEDA (6) observed that the internode of lateral shoot in Spring-cucumbers of South Chinese type was longer than that in Summercucumbers. On the other hand, MATsuo et al. (13,15) reported that at the same intensity of blue and red lights hypocotyl was longer in red light than in blue one and internode vice versa. More detailed studies on the hypocotyl elongation in cucumbers will clarify the correlation between the elongation of hypocotyl, internode, and lateral shoot. 2. Distortion of cotyledon : In a previous report (16) it was shown that the distortion occurred in cotyledons in coloured light. In this experiment the effect of intensities in blue and red lights on the occurrence of cotyledon distortion in different groups of cucumbers was observed. The distortion was graded as shown in Fig. 2. The results are shown in Table 5. The degree of cotyledon distortion at various intensities of red light were almost the same. In blue light, however, there was a tendency that the distortion was more striking as the light intensity was lower. Summer-cucumbers of South Chinese type and of Cross-bred type, and Spring-cucumbers of Cross-bred type showed a slight distortion. In the cucumbers of North Chinese type and Spring-cucumbers of South Chinese type, some cultivars showed

6 MATSUO:THE ECOLOGICAL CHARACTERISTICS OF HORTICULTURAL PLANTS 255 Table 5. Cotyledon distortion of cucumbers at various intensities of blue and red lights. a remarkable distortion, although others had only slight response. For example, `Sanjaku' cucumbers of North Chinese type showed more remarkable distortion than the others of it did both in blue and red lights. This tendency was prominent in blue light. Most cultivars of Spring-cucumber of South Chinese type showed greatest distortion both in blue and red lights. Cultivar `Ochiai-f ushinari', however, showed slighter distortion than any other cultivars of Spring-cucumber of South Chinese type. These data suggest that there might be a strain difference in cotyledon distortion in cucumbers of North Chinese type and of Spring-cucumber of South Chinese type. To clarify this point, the distortion of cotyledons as observed in different coloured lights are summarized in Table 6. The results of supplemental experiments on cotyledon distortion and hypocotyl elongation are presented in Table 7. In Spring-cucumbers of South Chinese type, cultivars belonging to `Han jiro' strain showed a remarkable distortion. In `Ao-f ushinari' strain, cultivars of `Ochiai' form (1,12) such as `Ochiai-f ushinari', `Ochiai No. 2', `Takesugata' and `Takemidori' showed a slight distortion and the other cultivars of `Aof ushinari' form such as `Ao-f ushinari' and of `Hyuga' form such as `Sairaku', `Hyuga No. 2', `Kurume-ochiai No. 2' and `Kurumeochiai H' showed a remarkable distortion. Cultivars belonging to Summer-cucumber of South Chinese type showed a slight distortion. As mentioned above, Spring-cucumbers of South Chinese type except `Ochiai' form showed a remarkable distortion in cotyledons. They were more sensitive to blue light than others in the hypocotyl elongation, although the hypocotyl length itself was short. Summercucumbers of South Chinese type showed a slight distortion. Their hypocotyl was longer than that of Spring-cucumbers (Tables 2, 5, 6 and 7, Fig. 1). In cucumbers belonging to North Chinese type, `Sanjaku' cucumbers showed a remarkable distortion and other cucumbers had very little. The former was more sensitive to blue light in hypocotyl elongation than the latter. The hypocotyl of the former was shorter than the latter (Tables 2, 3, 4, and 5).

7 256 JOURNAL OF THE JAPANESE SOCIETY FOR HORTICULTURAL SCIENCE Table 6. in Cotyledon distortion and hypocotyl length of South Chinese various coloured lights. cucumbers Table 7. Cotyledon distortion and length of Spring-cucumbers Chinese type in B2 and A2. hypocotyl of South Both Summer- and Spring-cucumbers of Cross-bred type in this experiment showed a slight distortion. They had longer hypocotyl than Spring-cucumbers of South Chinese type and were not so sensitive to blue light in hypocotyl elongation as Spring-cucumbers of South Chinese type (Tables 2, 4 and 5, Fig. 1). From these results, the remarkable distortion in cotyledon, short hypocotyl and sensitiveness to blue light in hypocotyl elongation may be thought as the characteristics of Springcucumbers of South Chinese type. In `Aofushinari' strain belonging to Spring-cucumber of South Chinese type, only the `Ochiai' form cucumbers showed a slight distortion. The growth responses of `Ochiai' cucumbers in field are quite similar to those of Summercucumbers. `Ao-f ushinari' strain is thought to be the offspring of the old type of `Aonaga' cucumber belonging to Summer-cucumber of South Chinese type (2,5). `Ao-fushinari' and `Hyuga' forms may owe thei r characters of remarkable distortion to `Hanjiro' strain of Spring-cucumber of South Chinese type. `Sanjaku' cucumbers of N orth Chinese type showed a remarkable distortion, especially in red light, and were rather sensitive to blue light in hypocotyl elongation. `Sanjaku' cucumber, cultivated recently, is shorter than the original one in fruit size (7). Taking these facts into view, `San jaku' cucumbers used may owe their characteristics to `Hanjiro' strain of Spring-cucumber of South Chinese type. More detailed investigations on the inheritance of cotyledon distortion and hypocotyl elongation will make it clear whether `Aof ushinari' and `Hyuga' forms of `Ao-f ushinari' strain and `San jaku' cucumbers of North Chinese type owe their characteristics on coty-

8 MATSUO : THE ECOROGICAL CHARAC TERISTICS OF HORTICULTURAL PLANTS 257 ledon distortion and hypocotyl elongation to Spring-cucumbers of South Chinese type. Acknowledgements The author is indebted to Dr. K. FUJIEDA (Oita Agric. Tech. Centre) for advice and cucumber seeds ; and Dr. Y. MINOHARA and colleagues (Cent. Res. Inst., Elect. Pow. Ind., Tokyo) for their help in preliminary experiments. Thanks are due to Dr. S. SUGAWARA (Nat. Hort. Res. Sta., Kurume), Dr. R. AKIYA (Sakata Shubyo Co., Ltd., Yokohama), for cucumber seeds ; to Prof. S. UEMOTO and Dr. S. M. PAUL (Kyushu Univ.), for their valuable advice on manuscript preparation and rectifying English version, respectively. Literature 1. AKIYA, R Personal communication. 2. Encyclopedia of Horticulture (Saishin Engei Daijiten) : ESASHI, Y Biological clock and creatures (1) (In Japanese). Nature (Shizen) 20(11) : Do. (2). Ibid. 20(12) : FUJIEDA, K Problems of cropping system, cultivars and cultivation (In Japanese). In Engei Zenpen. Yokendo, Tokyo: Ecologicol characteristics of cucumber cultivars which bear fruits on branches (In Japanese). Ann. Rep. Oita Agric. Tech. Centre : FUJIMOTO, K Cultivation of Summercucumbers in Kansai district, Japan (In Japanese). New techniques for cucumber cultivation. Seibundo-shinkosha, Tokyo: GATES, D. M Spectral distribution of solar radiation at the earth's surface. Science 151 : KUMAZAWA, S. and S. NISHIMURA Studies on the vegetables in Formosa and South China (In Japanese). Agr. & Hort. 12 : and K. KANAZAWA Introduction of North Chinese cucumbers and breeding of cultivar `Suyo' (In Japanese). J. Hort. Assoc. Japan 17 : M. MATSUMOTO and K. FUJIEDA Cucumber breeding. 1. Breeding of the cucumber bearing more fruits under the long day and high temperature condition (In Japanese). J. Hort. Assoc. Japan 24: 1-5. and R. AKIYA Cucumbers. In Special Olericulture (In Japanese). Revised edition. Ed. KUMAZAWA, S., Yokendo, Tokyo: MATSUO, E., Y. MINOHARA and S. TAKA- NASHI Studies on the growth behaviour of cucumber in controlled environment. 3. Effect of different photoperiodic combinations of various kinds of light on the growth and the sex differentiation of cucumber. J. Japan. Soc. Hort. Sci. 37 : MEIJER, G The spectral dependence of flowering and elongation. Acta Bot. Neerl. 8 : MINOHARA, Y., S. TAKANASHI and E. MATSUO Growth and development of horticultural plants in artificial lights. 1. Cucumber seedling in the light of different kind of spectral band. J. Agr. Lab., Cent. Res. Inst. Elect. Pow. Ind. 8 : A. SUNAGA and Do. 3. Correlation among the distortion of cotyledons of cucumber seedlings grown under monochromatic fluorescent lights, their ecotype concept and system of cropping. Ibid. 10: SHULGIN, A. I Solar radiation and plant (Japanese translation by Z, UCHIJIMA, 1970, Tokyo University Press, Tokyo). SNEDECOR, G. W Statistical methods (Japanesee translation by M.HATAMURA et al., 1962, Iwanami-shoten, Tokyo).

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