Zinc Treatment in Combination with Auxin Enhances Rooting of Cuttings in Taiwan Native Strain of Mango (Mangfera iindica L.)

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1 Jpn. J. Trop. Agr. 50 (2): 76-81, 2006 Zinc Treatment in Combination Auxin Enhances Rooting Cuttings in Taiwan Native Strain Mango (Mangfera iindica L.) Kensuke YAMASHITA, Shuji OKAMURA, Chitose HONSHO* Takuya TETSUMURA Faculty Agriculture, University Miyazaki Abstract To obtain a sustainable supply rootstocks, Taiwan native strain mango (Mangifera indica L.) was propagated by, using discarded shoots from young seedlings as rootstocks for grafting. Short (60 cm) were superior in rooting root length to long (90 cm). The use a non-lignified base resulted in a higher rooting percentage length value, compared to that a lignified base. Auxin exerted a beneficial effect on rooting on the number roots, while it significantly decreased the number shoots that sprouted. When the were zinc (ZnSO4 solution) in combination auxin, rooting was enhanced a positive interaction was found in the number roots generated. A combination NAA 1000 mgl-1 ZnSO4.7H2O 1000 mgl-1 resulted in optimum rooting (87.5%), while the application NAA 1000 mgl-1 ZnSO4 E7H2O 2000 mgl-1 induced the largest number roots (13.0). This is the first report on the effectiveness zinc treatment for cutting propagation mango. Key Words: nursery tree, propagation, rootstock Introduction Mango (Mangifera indica L.) is currently produced at the rate 26 million tons a year in the world (FAQ, 2004), which is the 5th largest production among all the fruits, following bananas, citrus, grapes apples. Consumption mango in Japan has been increasing year after year, import mango from foreign countries such as the Philippines Mexico amounted to 12,000 tons in In parallel the increase in the import mango, domestic production has tended to prevail in the Okinawa isls southern part Kyushu isl a production over 2,000 tons in Most the mango fruits grown in Japan consist the variety eirwin f, which was bred in Florida, USA (Campbell, 1992). Its red skin fiberless flesh are appreciated by the Japanese consumers. Since the domestically produced mangoes fetch a much higher price than the imported ones, the number new growers is increasing in the cultivated areas. In order to develop the domestic production mango, sustainable supply nursery plants to the growers is indispensable. However, the supply nursery plants has been occasionally inadequate in recent years, mainly due to the excess dem over supply, the lack rootstock plants. Taiwan native strain, which is polyembryonic, is generally used as Received Dec. 26, 2005 Accepted Mar. 11, 2006 * Corresponding author 1-1 Gakuenkibanadai-nishi, Miyazaki, Miyazaki , Japan chitose@pal.miyazaki-u.ac.jp rootstock in Japan. Most its seeds are imported from Taiwan then grown in Japan. Thus, the supply rootstocks totally depends on the Taiwan conditions the amount imported materials is currently decreasing. Moreover, it takes about three years from the import seeds to the sale nursery plants to mango growers through grafting scions. The long period time required to grow the nursery plants increases the price compared to that other temperate fruits, because mango plants must be kept in a heated greenhouse during winter. Efficient propagation the rootstocks shortening the duration the growth period the nursery plants may ensure a sustainable supply, leading to the expansion mango production in Japan. Thus, attempts were made to propagate rootstocks using collected from seedlings belonging to Taiwan native strain. Practically, when one- or two-year-old seedlings are grafted scions, the upper part the plant seedlings is being discarded. We thus attempted to use these discarded shoots as to obtain new plantlets for rootstocks. In cutting propagation, auxin is generally applied (Hartmann et al., 1997). Recently, it has been reported that zinc applied to a rice callus in combination auxin enhanced callus development rooting from the callus (Hossain et al., 1997). Therefore, we evaluated the suitability zinc application for cutting propagation mango in the present study. The objectives our study were as follows: 1) to demonstrate the effectiveness zinc treatment for

2 Yamashita et al.: Effect zinc auxin on cutting propagation in mango 77 rooting the, 2) to determine the optimal conditions for cutting propagation such as length concentrations zinc auxin. Materials Methods Effect length, auxin zinc treatment on rooting mango Two-year-old seedlings belonging to Taiwan native strain a height about 110 cm high were used in the present study. Long (90 cm) were prepared by cutting the shoots at 20 cm above the soil surface, while short (60 cm) at 50 cm. A 2-cm long crossing-split was made longitudinally at the base the, using pruning scissors for improving rooting the (Howard et al., 1987). Ten terminal leaves were left in all the. The base the was auxin (IBA (3-indolebutyric acid) or NAA (naphthalene acetic acid)) ZnSO4 E7H2O solution by dipping for 10 seconds in the solution. Combination concentration auxin ZnSO4 E7H2O were as follows, IBA alone, 2500 mgl-1; IBA 2500 mgl-1+znso E7H2O,1000 mgl-1; NAA alone, 2500 mgl-1; NAA 2500 mgl-1+znso4 E7H2O,1000 mgl-1; a control for both long short. Forty were tested in each treatment. Propagation bench is consisted a container (36 ~ 52 ~29 cm3 inside) filled river s, six were planted their base inserted to a 15 to 20 cm depth in the s. Cutting preparation was conducted in the middle April All the were covered a cheesecloth to shade f sunlight, kept under a propagation frame covered a plastic film the sides open. Adequate amount water was supplied every day to prevent water shortage. Rooting, number roots length the roots were recorded in the middle November the year were subjected to a statistical analysis the total length the roots being represented by the sum the length the primary roots. Data were analyzed by two-way ANOVA (length seedling belonging to Taiwan native strain was cut at 20 cm above the soil surface divided into two 40 cm-portions at the center. The base the lower half the shoot was lignified while that the upper half was not lignified. The number leaves was adjusted to seven for all the. The base the was cross-split (2 cm long) NAA (0, 1000, 2000 mgl-1). Thirty were used for each base condition NAA concentration. Cuttings were planted in May Propagation bench, treatment methods conditions were the same as those described in Experiment 1. Data related to the rooting, number roots total length primary roots were collected in November in the year. They were analyzed by t-test one-way ANOVA for the condition the base the NAA concentration, respectively. Effect interaction between zinc auxin on rooting mango One-year-old seedlings belonging to Taiwan native strain were cut at 40 cm above the soil surface. All the were adjusted to a 65 cm length terminal eight leaves. Crossing-split was performed at the base the the base was dipped into auxin /or ZnSO4 E7H2O solution. Seven treatments were designed as follows: ZnSO4 E7H2O only (100, 1000 or 2000 mgl-1); mixed solution NAA 1000 mgl-1 ZnSO4 E7H2O (100, 1000 or 2000 mgl-1); control. Forty were prepared in each treatment. Propagation bench, treatment methods conditions were the same as those described in the Experiment 1. This experiment was started in May 2003 the measurements related to the rooting, number roots length roots, were performed in the middle November in the year. Data including the number roots, number shoots total length the roots represented by the sum the length the primary roots were analyzed by two-way ANOVA for the NAA ZnSO4 treatments. Rooting was analyzed by t-test for the NAA treatment one-way ANOVA for the cutting treatment). As for the percentage rooting, ZnSO4 treatment. data were converted by angular transformation analyzed by t-test for the length the, by one-way ANOVA for the auxin treatment. Results Effect length auxin zinc treatment on rooting mango Influence the condition at the base the Rooting the short was more satisfactory on rooting To determine the influence the condition at the than that the long (Table 1). The highest rate (80%) was achieved in the short base the on rooting, two types were prepared. An 80 cm shoot from a two-year-old NAA. Effect the chemical treatment was significant in the number roots, effect the

3 78 Jpn. J. Trop. Agr. 50 (2) 2006 Table 1 Effect the length, auxin /or zinc treatments on rooting in mango Ns, *,** Nonsignificant or significant at P<0.05 or 0.01, respectively. z Different letters in a column indicate significant difference (P<0.05) by Tukey's test. cutting length was significant in the total length roots. When NAA+ZnSO4 was applied at the base the, the largest number roots (27.3 for the short 22.9 for the long ) was recorded. The value the total root length was the highest in the NAA+ZnSO4 (795cm) treatment for the short, while in the treatment IBA+ZnSO4 (504 cm) for the long. When ZnSO4 was applied in combination auxin, both the number roots total length roots increased compared to the treatment auxin alone, regardless the length the. Interaction between cutting length chemical treatment was not detected either in the number roots or total length roots. There was no considerable difference in the growth after rooting among the length values treatments. Influence the condition at the base the on rooting Rooting the a non-lignified base was significantly more satisfactory than that the a lignified base (Table 2). Cuttings a Table 2 Rooting the a non-lignified base vs. those a lignified base Ns, *Nonsignificant or significant at P<0.05, respectively.

4 Yamashita et al.: Effect zinc auxin on cutting propagation 79 in mango non-lignified base NAA at the rate 100 or 1000 mgl-1 showed the highest percentage Effect rooting (43.3%), while a lignified base rooting 100 mgl-1 NAA did not show any interaction The un control affected by the condition the base the. definitely enhanced The percentage NAA did not affect any measurements. Fig. 1 Rooting from ZnSO4 E7H2O indicates Table mango mgl-1, (C) seedling cutting Taiwan native NAA ones, (87.5 strain; the rooting %) auxin better than the zinc treatment NAA 1, Table recorded (B) NAA cutting ZnSO4 E7H2O 2000 for 3). the effect ZnSO4 on rooting sole treatment the cutting ZnSO4 combined treatment in mango NS,*,** Nonsignificant or significant at P<0.05 or 0.01, respectively. * Different letters in a column indicate significant difference (P<0.05) by Tukey's test. Highest ZnSO4 E7H20. mgl cm. Comparison on rooted (Fig. was mgl-1 (A) control, mgl-1 zinc rooting. Number total length the roots were not concentration between mango NAA Bar

5 80 Jpn. J. Trop. Agr. 50 (2) 2006 Regardless the concentrations ZnSO4, the NAA rooted better than those out NAA. NAA exerted a beneficial effect on the number roots, but an adverse effect on the number shoots. Numbers roots shoots were the largest in the treatment NAA 1000 mgl-1+znso4 E7H2O 2000 mgl-1 (13.0) in the control (2.0), respectively. Zinc sulfate exerted a significant effect both on the number total length the roots. The length the roots was significantly affected by both NAA ZnSO4. Interestingly, there was an interaction between NAA ZnSO4 in the number roots. Discussion In the present study, cutting propagation a mango rootstock strain was attempted in order to obtain a sustainable supply mango nursery plants. It is difficult to propagate mango by, because the plant does not regenerate roots easily sufficiently under general conditions for green shoot (Shu, 1992). Mukherjee et al. (1967) reported that the shoots from the seedlings young mango plants rooted better than those from old mango plants. Therefore, in the present experiment we targeted 1-to 3-year-old seedlings belonging to Taiwan native strain tried to propagate mango rootstocks by, as the first step clonal propagation. It is generally recognized that auxin exerts a beneficial effect on adventitious root formation in cutting propagation (Hartmann et al., 1997), this effect was also observed in the present study. Moreover, zinc treatment was found to enhance the rooting the mango. Although the mechanism underlying the role zinc in the rooting plants has not yet been elucidated, it was suggested that zinc can promote the formation tryptophan, an auxin precursor, which results in a higher auxin (IAA) level in plants (Hartmann et al., 1997). In fact, an increase in the tryptophan content a low auxin level was detected in zinc-deficient plants (Tsui, 1948). Auxininduced callus growth root formation were further enhanced by zinc treatment in rice (Hossain et al., 1997; Oguchi et al., 2004). The results obtained in the present study indicated that there was a significant improvement rooting by the zinc treatment, a positive interaction was detected when the were NAA ZnSO4. Hence, zinc seems to enhance the auxin activity or to increase the receptivity the to auxin. In recent studies, it was revealed that an auxin binding protein 1 (ABP1), which is a putative auxin receptor in plants, displayed a zinc-binding histidine cluster in its structure (Woo et al., 2002). Thus zinc may exert a promotive effect on ABPI by this bond. It is also interesting to note that the NAA treatment reduced the number sprouting shoots, which may be associated a change in hormonal balance by the application auxin at the base. Further studies on nutritional hormonal alterations in zinc- plants should be carried out in order to elucidate the performance zinc which might be associated the auxin function. Comparison the long short showed that the short rooted better produced a larger number roots longer roots than the long. As for apple, hard-wood 90-cm long showed good results compared 60- cm long (Howard Harrison-Murray, 1983). In that case, it is suggested that the longer stored a larger quantity assimilation products, leading to fine rooting. In the case mango, however, the results did not correspond to those apple. The lower percentage rooting the long may be associated to the condition at the base the. In the present study, it was shown that the use a lignified base resulted in less satisfactory rooting than that a nonlignified base (Table 2). Hardened tissue may prevent root formation or absorption nutrients /or water. Thus, the short may survive over a longer period time than the long under the conditions prevailing in the present study. In conclusion, we showed that the rooting the mango could be improved by combined treatment auxin zinc. The most effective combination for rooting was the application 1000 mgl-1 NAA 2000 mgl-1 ZnSO4 E7H2O. Although rooting the mango was successful, some aspects should be considered for further improving rooting. For instance, measures such as the use a mist chamber, provision bottom heat application some pre-treatments, which had been previously reported to be effective in mango, should be adopted (Reuveni et al., 1991; Reuveni Castoriano, 1993; Shu, 1979; 1992; Schaesberg Ludders, 1991). Since rootstocks from seedlings generally have strong taproots but fewer feeder roots, the uptake micronutrients would be inadequate partial black spots in the young fruit caused by boron deficiency may occur occasionally, when the plants are grown in a limited rhizosphere. Since rootstocks from rooted

6 Yamashita et al.: Effect zinc auxin on cutting propagation in mango 81 develop a large amount adventitious roots feeder roots, most them display shallow rooting in general. Mango in Japan must be grown in the greenhouse under dense planting (Yamashita, 2000). Therefore, using the rooted as rootstocks may be beneficial to Japanese growers for maintaining a small canopy. In this line research, top growth the scions which are grafted on seedling rootstocks rooted cutting rootstocks should be compared. Also, shoot cutting scion cultivars to obtain self rooted plants has been undertaken Acknowledgement in our laboratory. Authors thank JA Agriseed (Miyazaki, Japan) for providing the plant materials. References Campbell, R. J Guide to Mangos in Florida. Fairchild Tropical Gardens (Florida) p.227. FAO FAO Yearbook Production : 185. Hartmann, H. T., D. E. Kester, F. T. Davies, Jr. R. L. Geneve Plant propagation: principles practices (6th ed.). Prentice Hall, New Jersey, USA. Hossain, B., N. Hirata, Y. Nagatomo, R. Akashi H. Takaki Internal zinc accumulation is correlated increased growth in rice suspension culture. J. Plant Growth Regul. 16: Howard, B. H. R. S. Harrison-Murray Plant propagation cutting techniques. Rep. East Malling Res. Report: Howard, B. H., R. S. Harrison-Murray K. A. D. Mackenzie Rooting responses to wounding winter M.26 apple rootstock. J. Hort. Sci. 59: Mukherjee, S. K., P. K. Majumder, N. N. Bid A. M. Goswami Stardization rootstocks mango (Mangifera indica L.) II. Studies on the effects source, invigoration etiolation on the rooting mango. J. Hort. Sci. 42: Oguchi, K., N. Tanaka, S. Komatsu S. Akao Methylmalonate-semialdehyde dehydrogenase is induced in auxin-stimulated zinc-stimulated root formation in rice. Plant Cell Rep. 22: Reuveni, O. M. Castoriano Effect bottom heat temperatures on rooting mango different cultivars. Acta Hort. 341: Reuveni, O., W. Kuepper J. Wiedel Rooting mango under intermittent mist. Acta Hort. 291: Shu, M. K Pre-treatments stock plants different growth regulating chemicals to induce rooting on mango. Acta Hort. 321: Shu, M. K Effect pretreatments stock plants mango cycocel, ethrel morphactin on the rooting cutting air layers. Sci. Hort. 10: Schaesberg, N. V. P. Ludders Influence stockplant pretreatment on the rooting ability three Mangifera indica L. rootstocks. Acta Hort. 291: Tsui, C The role zinc in auxin synthesis in tomato plants. Amer. J. Bot. 35: Yamashita, K Mango production in Japan. Acta Hort. 509: Woo, E. -J., J. Marshall, J. Bauly, J. -G. Chen, M. Venis, R. M. Napier R. W. Pickersgill Crystal structure auxinbinding protein 1 in complex auxin. EMBO J. 21: *Corresponding author chitose@pal.miyazaki-u.ac.jp