Planta
Planta 143, 3 3 1 - 3 3 2 (1978)
9 by Springer-Verlag 1978
Short Communication
Interaction of Gibberellic and lndole-3-acetic Acid on Root Formation in Pea (Pisum sativum L.) Epicotyl Cuttings U.K. Adhikari and D. Bajracharya 1 Botany Instruction Committee, Tribhuvan University, Kirtipur Campus, K a t h m a n d u , Nepal
Abstract. Indole-3 acetic acid (IAA) strongly enh a n c e d rooting o f e h ~lated pea epicotyl cuttings while
gibberellic acid (GA3) enhanced rooting only slightly. The promoting effects of the hormones appeared not until 14 d after the onset of treatment. When GA~ and IAA were applied together, the initiation of rooting started already after 6 d after onset of treatment. It is suggested that gibberellin plays an important role, in combination with auxin, in the initiation of root formation in P i s u m cuttings. Key words: A u x i n - Gibberellin - Interaction (horm o n e s ) - P i s u m - Root formation.
Fifteen 3 cm long apical epicotyI cuttings were prepared from uniform 6 d-old dark-grown seedlings. The cuttings were surface sterilised in 0.3% sodium hypochlorite solution for 2 min and subsequently transfered, after thorough washing with sterilised water, to petridishes containing one layer of filter paper and 3 ml of test solutions which were sterilised by passing through a m e m b r a n e filter. To avoid the interaction of light with rooting, the cuttings were maintained in the dark at 25 ~ C. Fresh test solutions (3 ml) were added to each petridish every third day. The concentrations 30 g m o l . l - 1 of hormones used in the present experiments have been found to be optimal with respect to root initiation. All manipulations were performed under sterile conditions. The percentage of rooted cuttings was determined in 2 d-intervals. The values given in the diagram are mean of two independent experiments each with three replicates.
Results and Discussion
Figure 1 shows that IAA significantly promotes root formation in etiolated pea epicotyl cuttings after 12 d Introduction
There are conflicting reports with respect to the role of GA3 on the formation of adventitous roots in the cuttings. In some cases, GA 3 was found to have inhibitory effect (Brian et al., 1960; Jansen, 1967; Nanda et al., 1968 ; Fellenberg, 1969). In pea cuttings, the effect of GA3 depended on the preradiation of the stock plant from which the cuttings were obtained (Hansen, 1976). In other instances, GA3 promoted root formation (Nanda et al., 1972; Bhattacharya et al., 1978). The present paper shows that GA3 alone promotes root formation only slightly in etiolated pea epicotyl cuttings, however considerably enhances the promotive effect of IAA on root formation.
Materials and Methods Pea seeds were obtained from the Department of Agriculture, Khumultar (Kathmandu). To w h o m enquiries and reprint requests should be adressed Abbreviations :
I A A = Indole-3-acetic acid ; GA3 = Gibberellic acid
30 -
/
GA3+ZAA
Z == o
6A 3
0 ~+q--,'-'-.H,,y-l
.
6
10
8
.
. 12
. 14
.
.
16
,, 18
20
22
days after incubation Fig. 1. The effect of gibberellic acid (GAs) and indole-3-acetic acid (IAA), when used individually or in combination, on the rooting of etiolated pea epicotyl cuttings. The concentrations of hormones were 30 gmol.1 1
0032-0935/78/0143/0331/$01.00
332
U.K. Adhikari and D. Bajracharya: Interaction of Gibberellic and Indole-3-acetic Acid on Root Formation
of incubation. Maximum rooting was achieved 20 d after incubation. GAa, when used alone, has only a slighlty promotory effect. But when GA3 and IAA were applied together, rooting of the cuttings started much earlier and reached a maximal value earlier than when either of the hormones was applied individually. Though the initiation of root formation started much earlier in the presence of both hormones, the maximum rooting observed was nearly equal to the sum of rooting observed in the presence of individual hormone. In other words, the effects of GA3 and IAA appear to be additive with respect to the maximum rooting potential of the pea cuttings but synergistic with respect to their effect on the temporal initiation of root formation. A similar interaction of GA3 and IAA has been first reported by Bhattacharya et al. (1978) who found that in the presence of GA3 and IAA the number of roots formed per cutting from Abelrnoschus esculentus was greater than the sum of roots formed in individual treatments. However, the information on the interaction between GA 3 and IAA on the temporal initiation of rooting of A. esculentus cuttings could not be obtained in this case because the authors recorded rooting only by end point determination 30 d after addition of hormones. The present work shows that the major action of GAg in rooting of Pisum cuttings in the presence of saturating amount of IAA is to enhance this process rather than to increase the number of rooting cuttings. It may, therefore, be presumed that the low level of rooting observed in the induction of root formation by IAA alone (Fig. 1) may be due to the low level of endogenous GAg in the tissue. Similarly, the failure
of GA3 alone to promote root formation could be due to the low level of endogenous auxin in the cuttings. Thus, an appropriate combination of gibberellin and auxin appears to be necessary for root initiation. This work constitutes a part of M.Sc thesis submitted by U.K.A. to Tribhuvan University (Nepal). The authors are grateful to the university authorities, T.U,, for the research facilities and Professor P. Schopfer, University of Freiburg, for valuable suggestions.
References Bhattacharya, S., Bhattacharya, N.C., Malik, C.P.: Synergistic effect of gibberellic acid and indole-3-acetic acid on rooting in stem cuttings of Abelmoschus esculentus Moench. Planta 138,
111 112 (1978) Brian, P.W., Hemming, H.G., Lowe, D.: Inhibition of rooting of cuttings by gibberellic acid. Ann. Bot. 24, 407-419 (1960) Fellenberg, G.: Influence of GA3 and kinetin upon auxin-induced root initiation and nucleoproteins of pea epicotyls. Z. Pflanzenphysiol. 60, 457-466 (1969) Hansen, J.: Adventituous root formation induced by gibberellic acid and regulated by the irradiation to the stock plants. Physiol. Plant, 36, 77-81 (1976) Jansen, H. : Die Wirkung yon Gibberellins/iure und Indolylessigs~iure auf die Wurzelbildung yon Tomatenstecklingen. Planta 74, 371-378 (1967) Nanda, K.K., Ananda, V.K., Chibbar, R.N.: Promotive effect of gibberellic acid on the production of adventituous roots on stem cuttings of Ipomoeafistula. Planta 105, 360-363 (1972) Nanda, K.K., Purohit, A.N., Mehrotra, K.: Effect of sucrose, auxins and gibberellic acid on rooting of stem segments of Populus n~,ra under varying light conditions. Plant Cell Physiol. 9, 735 743 (1968) Received 18 July; accepted 26 July 1978
Planta 143, 3 3 1 - 3 3 2 (1978)
9 by Springer-Verlag 1978
Short Communication
Interaction of Gibberellic and lndole-3-acetic Acid on Root Formation in Pea (Pisum sativum L.) Epicotyl Cuttings U.K. Adhikari and D. Bajracharya 1 Botany Instruction Committee, Tribhuvan University, Kirtipur Campus, K a t h m a n d u , Nepal
Abstract. Indole-3 acetic acid (IAA) strongly enh a n c e d rooting o f e h ~lated pea epicotyl cuttings while
gibberellic acid (GA3) enhanced rooting only slightly. The promoting effects of the hormones appeared not until 14 d after the onset of treatment. When GA~ and IAA were applied together, the initiation of rooting started already after 6 d after onset of treatment. It is suggested that gibberellin plays an important role, in combination with auxin, in the initiation of root formation in P i s u m cuttings. Key words: A u x i n - Gibberellin - Interaction (horm o n e s ) - P i s u m - Root formation.
Fifteen 3 cm long apical epicotyI cuttings were prepared from uniform 6 d-old dark-grown seedlings. The cuttings were surface sterilised in 0.3% sodium hypochlorite solution for 2 min and subsequently transfered, after thorough washing with sterilised water, to petridishes containing one layer of filter paper and 3 ml of test solutions which were sterilised by passing through a m e m b r a n e filter. To avoid the interaction of light with rooting, the cuttings were maintained in the dark at 25 ~ C. Fresh test solutions (3 ml) were added to each petridish every third day. The concentrations 30 g m o l . l - 1 of hormones used in the present experiments have been found to be optimal with respect to root initiation. All manipulations were performed under sterile conditions. The percentage of rooted cuttings was determined in 2 d-intervals. The values given in the diagram are mean of two independent experiments each with three replicates.
Results and Discussion
Figure 1 shows that IAA significantly promotes root formation in etiolated pea epicotyl cuttings after 12 d Introduction
There are conflicting reports with respect to the role of GA3 on the formation of adventitous roots in the cuttings. In some cases, GA 3 was found to have inhibitory effect (Brian et al., 1960; Jansen, 1967; Nanda et al., 1968 ; Fellenberg, 1969). In pea cuttings, the effect of GA3 depended on the preradiation of the stock plant from which the cuttings were obtained (Hansen, 1976). In other instances, GA3 promoted root formation (Nanda et al., 1972; Bhattacharya et al., 1978). The present paper shows that GA3 alone promotes root formation only slightly in etiolated pea epicotyl cuttings, however considerably enhances the promotive effect of IAA on root formation.
Materials and Methods Pea seeds were obtained from the Department of Agriculture, Khumultar (Kathmandu). To w h o m enquiries and reprint requests should be adressed Abbreviations :
I A A = Indole-3-acetic acid ; GA3 = Gibberellic acid
30 -
/
GA3+ZAA
Z == o
6A 3
0 ~+q--,'-'-.H,,y-l
.
6
10
8
.
. 12
. 14
.
.
16
,, 18
20
22
days after incubation Fig. 1. The effect of gibberellic acid (GAs) and indole-3-acetic acid (IAA), when used individually or in combination, on the rooting of etiolated pea epicotyl cuttings. The concentrations of hormones were 30 gmol.1 1
0032-0935/78/0143/0331/$01.00
332
U.K. Adhikari and D. Bajracharya: Interaction of Gibberellic and Indole-3-acetic Acid on Root Formation
of incubation. Maximum rooting was achieved 20 d after incubation. GAa, when used alone, has only a slighlty promotory effect. But when GA3 and IAA were applied together, rooting of the cuttings started much earlier and reached a maximal value earlier than when either of the hormones was applied individually. Though the initiation of root formation started much earlier in the presence of both hormones, the maximum rooting observed was nearly equal to the sum of rooting observed in the presence of individual hormone. In other words, the effects of GA3 and IAA appear to be additive with respect to the maximum rooting potential of the pea cuttings but synergistic with respect to their effect on the temporal initiation of root formation. A similar interaction of GA3 and IAA has been first reported by Bhattacharya et al. (1978) who found that in the presence of GA3 and IAA the number of roots formed per cutting from Abelrnoschus esculentus was greater than the sum of roots formed in individual treatments. However, the information on the interaction between GA 3 and IAA on the temporal initiation of rooting of A. esculentus cuttings could not be obtained in this case because the authors recorded rooting only by end point determination 30 d after addition of hormones. The present work shows that the major action of GAg in rooting of Pisum cuttings in the presence of saturating amount of IAA is to enhance this process rather than to increase the number of rooting cuttings. It may, therefore, be presumed that the low level of rooting observed in the induction of root formation by IAA alone (Fig. 1) may be due to the low level of endogenous GAg in the tissue. Similarly, the failure
of GA3 alone to promote root formation could be due to the low level of endogenous auxin in the cuttings. Thus, an appropriate combination of gibberellin and auxin appears to be necessary for root initiation. This work constitutes a part of M.Sc thesis submitted by U.K.A. to Tribhuvan University (Nepal). The authors are grateful to the university authorities, T.U,, for the research facilities and Professor P. Schopfer, University of Freiburg, for valuable suggestions.
References Bhattacharya, S., Bhattacharya, N.C., Malik, C.P.: Synergistic effect of gibberellic acid and indole-3-acetic acid on rooting in stem cuttings of Abelmoschus esculentus Moench. Planta 138,
111 112 (1978) Brian, P.W., Hemming, H.G., Lowe, D.: Inhibition of rooting of cuttings by gibberellic acid. Ann. Bot. 24, 407-419 (1960) Fellenberg, G.: Influence of GA3 and kinetin upon auxin-induced root initiation and nucleoproteins of pea epicotyls. Z. Pflanzenphysiol. 60, 457-466 (1969) Hansen, J.: Adventituous root formation induced by gibberellic acid and regulated by the irradiation to the stock plants. Physiol. Plant, 36, 77-81 (1976) Jansen, H. : Die Wirkung yon Gibberellins/iure und Indolylessigs~iure auf die Wurzelbildung yon Tomatenstecklingen. Planta 74, 371-378 (1967) Nanda, K.K., Ananda, V.K., Chibbar, R.N.: Promotive effect of gibberellic acid on the production of adventituous roots on stem cuttings of Ipomoeafistula. Planta 105, 360-363 (1972) Nanda, K.K., Purohit, A.N., Mehrotra, K.: Effect of sucrose, auxins and gibberellic acid on rooting of stem segments of Populus n~,ra under varying light conditions. Plant Cell Physiol. 9, 735 743 (1968) Received 18 July; accepted 26 July 1978
![[The effect of gibberellic acid and indoleacetic acid on the root formation of tomato cuttings].](/assets/img/hold.png)
