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Biochemical changes associated with floral malformation in mango
Scientia Horticulturae, 6 (1977) 37--44 Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands
37
B I O C H E M I C A L C H A N G E S A S S O C I A T E D WITH FLORAL MALFORMATION I N MANGO
R.M. PANDEY, M.M. RAO and R.A. PATHAK Division of Horticulture and Fruit Technology, Indian Agricultural Research Institute, New Delhi (India) (First received 11 November 1975; in revised form 18 May 1976)
ABSTRACT Pandey, R.M., Rao, M.M. and Pathak, R.A., 1977. Biochemical changes associated with floral malformation in mango. Scientia Hort., 6: 37--44. Changes in carbohydrate reserves and in total nitrogen, and the anatomy of healthy and malformed shoots of mango cultivars 'Dashehari' and 'Chausa' were followed before and after fruit-bud differentiation. Acid hydrolysable polysaccharides and total carbohydrates remained at higher levels in leaves, stems and panicles of malformed shoots as compared to healthy ones in both the cultivars. The total nitrogen did not show much change. Marked anatomical differences were noted in rachis of both types of panicles. The floral malformation was observed to be associated with the accumulation of excessive amounts of acid hydrolysable polysaccharides. Two possible ways of explaining the behaviour of malformed shoots have been suggested.
INTRODUCTION M a l f o r m a t i o n , w h i c h is o n e o f t h e m o s t serious p r o b l e m s o f m a n g o (Mangifera indica L.), causes g r e a t e c o n o m i c loss in India. It has b e e n divided i n t o t w o groups, v e g e t a t i v e a n d floral, d e p e n d i n g o n t h e p a r t s m a l f o r m e d . Floral m a l f o r m a t i o n , w h i c h is t h e s u b j e c t o f this s t u d y , is w i d e l y d i s t r i b u t e d all over India, a l t h o u g h t h e i n c i d e n c e is g r e a t e r in t h e N o r t h - W e s t t h a n in t h e N o r t h E a s t or S o u t h . A l t h o u g h this p r o b l e m e x i s t e d f o r a l o n g t i m e , t h e first des c r i p t i o n was m a d e b y Burns ( 1 9 1 0 ) in P o o n a (India). R e c e n t l y this m a l a d y has also b e e n r e p o r t e d f r o m P a k i s t a n ( K h a n a n d K h a n , 1 9 6 0 ) , Central A m e r i c a , M e x i c o a n d Israel (Malo a n d McMillan, 1972). T h e u n i q u e and visible s y m p t o m is a d e f o r m a t i o n o f t h e panicles w h i c h consists m a i n l y in a s h o r t e n i n g o f t h e p r i m a r y and s e c o n d a r y axes and t h i c k e n e d rachis, giving t h e f l o w e r s a c h a r a c t e r i s t i c c l u s t e r e d a p p e a r a n c e (Fig. 1 ). F l o w e r s o f m a l f o r m e d panicles are bigger t h a n n o r m a l a n d are m o s t l y male. A f f e c t e d panicles v e r y s e l d o m set fruit, a n d u l t i m a t e l y d r y up, r e m a i n i n g on t h e t r e e f o r m a n y m o n t h s as b l a c k masses o f d e a d tissue. It is v e r y c o m m o n
38
Fig.1. Healthy (left) and malformed (right) panicles of mango.
to see healthy and malformed panicles side by side or on the same branch. Another s y m p t o m , perhaps less evident~ is a swelling of the vegetative buds accompanied by a shortening of the internodes. When studying the 3 reviews on mango malformation (Prasad et al., 1965; Butani and Srivastava, 1973; Varma et al., 1974a), it is clear that the biochemical knowledge of this malady is poor. Most of the studies in the past have been of a general nature (Khan and Khan, 1960, 1962; Narsinham, 1959; Nirvan, 1953; Schlosser, 1971; Summanwar et al., 1966; Majumder et al., 1970). Only recently has some work been initiated on this aspect in particular (Pandey et al., 1973, 1974, 1975). In the present investigation an attempt has been made to find o u t the changes in the major constituents of leaves, stems and panicles and also in the anatomy of normal and malformed rachis of 'Dashehari' and 'Chausa', which are popular mango cultivars of Northern India. MATERIALS AND METHODS
The present investigation was carried o u t in the experimental orchard of the Indian Agricultural Research Institute, New Delhi, using 20-year-old trees of 2 commercial cultivars of mango, viz. 'Dashehari' and 'Chausa', grown under uniform cultural practices in 1973 and 1974. Averages of data for 2 years will be presented. Samples were collected at 2 different periods, before and after fruit-bud differentiation. Before fruit-bud differentiation malformed shoots were identified by the presence of scars. Samples of shoots (leaves and stems separately), carrying both healthy and malformed panicles were dried at 70 ° C
39
for 48 h and were analysed in triplicate for various constituents. Panicles were sampled when they were 7.5--10 cm long. Homogenate samples of leaves, stems and panicles were later extracted with ethanol, and carbohydrate fractions in the extract were separated by using ion-exchange columns (Rao~ 1973). Sugars were determined by the m e t h o d of Somogyi (1945), acid hydrolysable polysaccharides after Asana and Saini (1962) and total nitrogen by micro-kjeldahl. The procedure for chlorophyll determination was based on the method described by Arnon {1949). Anatomical differences between healthy and malformed panicles were studied by cutting the rachis with the aid of a microtome. The thickness of the rachis was measured by vernier callipers. The results of the study were statistically analysed by analysis of variance given by Panse and Sukhatme (1967). RESULTS
Changes in carbohydrate reserves and total nitrogen in different parts o f healthy and malformed shoots o f mango before fruit-bud differentiation. -From the data given in Table 1, it is clear that levels of reducing and total sugars were significantly higher in leaves of healthy shoots than in malformed ones in both cultivars. The higher content of non-reducing sugars observed in leaves of healthy shoots of both cultivars in comparison to malformed ones was statistically insignificant. Except for the non-reducing sugars in 'Dashehari', the difference recorded for the higher content of reducing, non-reducing and total sugars in stems of healthy shoots was insignificant as compared to malformed shoots in both cultivars. However, acid hydrolysable polysaccharides showed different patterns of accumulation; i.e. the amount remained at a significantly higher level in leaves and stems of malformed shoots than in healthy ones in both cultivars. The higher level of total carbohydrates in leaves and stems of malformed shoots as compared to the corresponding parts of healthy shoots was mainly due to an excess a m o u n t of acid hydrolysable polysaccharides. Similar results have been reported by Pandey et al. (1973) in the case of vegetative malformation of mango cultivar ' B o m b a y Green'. Unlike earlier findings pertaining to vegetative malformation, in the present case the levels of reducing and total sugars were higher in leaves and stems of healthy shoots than in malformed ones. With the exception of the stem of 'Dashehari', there was significantly higher content of N in leaves and stems of healthy shoots than in malformed ones in both cultivars. The carbohydrate and nitrogen ratios observed in leaves and stems of malformed shoots were significantly higher than in healthy ones in both cultivars. In addition, while a great difference was observed in the content of chlorophyll in healthy and malformed shoots of vegetative malformation (Pandey et al., 1973), practically no difference was observed in floral malformation. For example, the amounts of chlorophyll a, b and total in leaves of healthy shoots were found to be 6 mg, 12.6 mg and 18.6 mg per g.f.wt, respectively, while the corresponding values in the leaves of malformed shoots were 6 mg, 12.2 mg
40
and 18.2 mg per g.f.wt, respectively. This suggests that perhaps different mechanisms are involved in controlling the 2 types of malformation. Changes in carbohydrate reserves and total nitrogen in different parts of healthy and malformed shoots of mango after fruit-bud differentiation. -- The data pertaining to various constituents have been presented in Table 2. Comparing these data with those of Table 1 we see that, with the exception of nonreducing sugars, the levels of reducing and total sugars, total carbohydrates, total nitrogen and also C/N ratio declined in the leaves of healthy and malformed shoots of both cultivars after fruit-bud differentiation. Although decline in these constituents was noticed with age, the levels of acid hydrolysable polysaccharides and total carbohydrates remained at a significantly higher level in the leaves of malformed shoots than in healthy ones. While the levels of reducing and total sugars in the stems of healthy and malformed shoots declined, the levels of non-reducing sugars, acid hydrolysable polysaccharides and C/N ratio increased with age, i.e. after fruit-bud differentiation. One of the salient features of the present findings was that the level of total carbohydrates decreased in the leaves with a corresponding increase in the stems. This fact indicates the mobilization of carbohydrate from the site of synthesis to the site of utilization, perhaps for fruit-bud differentiation. Similar results have been reported by earlier workers (Singh, 1960; Sen et al., 1963). TABLE 1 A m o u n t o f various f r a c t i o n s o f c a r b o h y d r a t e s a n d t o t a l n i t r o g e n in d i f f e r e n t p a r t s o f h e a l t h y and m a l f o r m e d s h o o t s o f m a n g o b e f o r e f r u i t - b u d d i f f e r e n t i a t i o n , e x p r e s s e d as % d r y weight.
Constituents
Organ
'Dashehari' Healthy
'Chausa' Malformed
Healthy
Malformed
C.D. at 5% between 2 treatments means for a given cultivar
Reducing sugars
Leaf Stem
5.00 4.65
4.60 4.55
4.22 4.75
3.60 4.60
0.20 NS
Non-reducing
Leaf Stem
1.03 0.85
1.00 0.45
1.30 0.25
0.76 0.15
NS 0.11
Total sugars
Leaf Stem
6.03 5.50
5.60 5.00
5.50 5.00
4,38 4.75
0.31 NS
Acid hydrolyssble polysaccharides
Leaf Stem
12.60 20.25
12.96 21.60
13.14 16.77
14.40 18,90
0.27 0.14
Total
Leaf Stem
18.63 25.75
18.56 26.60
18.64 21.47
18.78 23,65
0.05 0.05
Total nitrogen
Leaf Stem
2.00 1.05
1.90 1.00
1.65 1.20
1.45 0.95
0.09 0.12
C/N ratio
Leaf Stem
9.32 24.52
9.76 26.60
11.30 17.89
12,95 24.69
0.12 0.06
sugars
carbohydrates
41
TABLE 2 A m o u n t o f various f r a c t i o n s o f c a r b o h y d r a t e and t o t a l n i t r o g e n in d i f f e r e n t p a r t s o f h e a l t h y and m a l f o r m e d s h o o t s o f m a n g o a f t e r f r u i t - b u d d i f f e r e n t i a t i o n , e x p r e s s e d as % d r y weight.
Constituents
Organ
'Dashehari' Healthy
'Chausa' Malformed
Healthy
Malformed
C.D. at 5% between 2 treatments means for a given cultivar
Reducing sugars
Leaf Stem Panicle
3.70 3.40 4.45
3.00 2.70 4.00
3.95 3.25 4.85
3.40 3.00 4.20
NS 0.21 NS
Non-reducing sugars
Leaf 'Stem Panicle
1.38 1.10 0.93
1.18 0.55 1.00
1.73 0.75 0.80
1.43 0.33 0.65
0.10 0.10 0.14
Total sugars
Leaf Stem Panicle
5.08 4.50 5.38
4.18 3.25 5.00
5.68 4.00 5.65
4.83 3.33 4.85
NS 0.19 NS
Acid hydrolysable polysaccharides
Leaf 10.26 Stem 25.20 Panicle 18.00
12.26 26.19 18.80
11.16 21.60 17.10
12.52 26.19 19.08
0.27 NS 0.14
Total carbohydrates
Leaf 15.34 Stem 29.70 Panicle 23.38
16.44 29.44 23.80
16.84 25.60 22.75
17.35 29.52 23.93
0.27 0.39 0.13
Total nitrogen
Leaf Stem Panicle
1.90 1.15 1.85
1.80 0.90 1.80
1.60 1.10 1.85
1.55 1.05 1.80
C/N ratio
Leaf 8.07 Stem 25.82 Panicle 12.63
9.13 32.71 13.22
10.52 23.27 12.30
11.19 28.11 13.29
NS NS NS 0.47 0.37 0.13
Although malformed stems contained the m a x i m u m a m o u n t of total carbohydrates and differentiated fruiting-buds, the same as healthy ones, t h e y did n o t develop normal panicles. The higher levels of reducing sugars and total sugars were statistically insignificant in healthy panicles as compared to malformed ones in both cultivars, while a reverse trend was observed for the c o n t e n t of acid hydrolysable polysaccharides and total carbohydrates. Here again, as with stems and leaves, the a m o u n t of acid hydrolysable polysaccharides remained at a higher level in malformed panicles. Anatomical changes in rachis o f healthy and malformed panicles o f mango. -As seen from Table 3, the thickness of the malformed rachis was approximately twice t h a t of the healthy one in both cultivars. Furthermore, the number of cells per unit area of cortex, xylem vessels and pith was llh times less in mal-
42
TABLE 3 Anatomical differences in the rachis of healthy and malformed panicles of mango. Organ
Measurement
'Dashehari' Healthy
'Chausa' Malformed
Healthy
Malformed
3.2
6.3
3.5
6.8
Epidermis Thickness (u)
13.4
24.1
17.4
28.1
Cortex
No. of cells per field
22
15
31
19
Size of cells length X breadth (u)
28.1 × 25,5
38.9 x 29.8
21.4 x 17.4
30.8 × 28.1
No. of cells per field
12
Size of cells length X breadth (u)
22.8 x 20.1
No. of cells per field
16
Size of cells length X breadth (u)
34.8 x 29.5
Rachis
Xylem vessels
Pith
Thickness (ram)
8
37.5 x 29.5
9
52.3 × 46.9
15
18.8 × 16.1
26
34.8 × 28.1
8
45.6 × 25.5
8
59.0 × 54.9
formed panicles than in healthy ones. The thickness of rachis and the smaller number of cells/field in the rachis of malformed panicles were a function of cell size, which was greater in the case of malformed rachis. DISCUSSION
Observed data indicated that the level of acid hydrolysable polysaccharides which is favourable for the induction of floral primordia (Singh, 1960) was higher in leaves, stems and panicles of malformed shoots than in those of healthy ones before fruit-bud differentiation. Their level remained higher even after fruit-bud differentiation. This brings out the possibility that perhaps acid hydrolysable polysaccharides in malformed panicles are not being hydrolysed into simple sugars in the same manner as they are hydrolysed in normal panicles~ to meet the energy requirement of the panicles for their normal development. Therefore, although fruit-bud differentiation in 2 types of panicles takes place simultaneously, the normal development of the panicles borne on malformed shoots is suppressed. On the basis of the above facts, 2 possibilities have been suggested to explain the peculiar behaviour of malformed panicles. Firstly, there may be certain pa-
43
thogens involved in causing the disturbances in the metabolism (Varma et al., 1974b). Secondly, there may be imbalance between growth promoters and growth inhibitors, which are in some way linked with this phenomenon (Pandey et al., 1974). Since this malady can be controlled to a great extent by spraying with ~-napthyleneacetic acid (200 p.p.m.) (Majumder et al., 1970), the second possibility seems to be more plausible. ACKNOWLEDGEMENTS
Grateful thanks are due to Dr. R.N. Singh, Head Division of Horticulture and Fruit Technology, Indian Agricultural Research Institute~ New Delhi, for providing facilities. REFERENCES Arnon, D.I., 1949. Copper enzymes in isolated chloroplasts. Plant Physiol., 24: 1--15. Asana, R.D. and Saini, A.D., 1962. Studies in physiological analysis of yield. V. Grain development in wheat in relation to temperature, soil moisture and age in sugar content of stem and in photosynthetic surface. Ind. J. Plant Physiol., 5: 128--171. Burns, W., 1910. A c o m m o n malformation of mango inflorescence. Poona Agric. Coll. Mag.~ 2: 38--39. Butani, and Srivastava, R.P., 1973. La "Malformation" du manguier. Fruits, 28: 389--395. Khan, M.D. and Khan, A.H., 1960. Studies on malformation of mango inflorescence in West Pakistan. Punjab Fruit J., 23: 247--258. Khan, M.D. and Khan, A.H., 1962. Relation of growth to malformation of inflorescence in mango. West Pak. J. Agric. Res., 1: 51--63. Majumder, P.K., Sinha, G.C. and Singh, R.N., 1970. Effect of exogenous application of napthyleneacetic acid on mango (Mangifera indica L. ) malformation. Indian J. Hortic., 27: 130--131. Malo, S.E. and McMillan, Jr., 1972. A disease of Mangifera indica L. in Florida similar to mango malformation. Proc. F1. State Hortic. Soc., 85: 264--268. Narsinham, M.J., 1959. Control of mango (inflorescence) malformation disease. Curr. Sci., 28: 254--257. Nirvan, R.S., 1953. Bunchy top of young mango seedlings. Sci. Cult., 18: 333--334. Pandey, R.M., Sinha, G.C., Singh, R.N. and Majumder, P.K., 1973. Some biochemical aspects of vegetative malformation in mango (M. indica L. ) I. Carbohydrate reserves and nitrogenous fractions. Indian J. Hortic., 3: 475--480. Pandey, R.M., Rathore, D.S. and Singh, R.N., 1974. Hormonal regulation of mango malformation. Curr. Sci., 43: 694---695. Pandey, R.M., Singh, R.N. and Rao, M.M., 1975. Nucleic acid and protein levels in healthy and malformed panicles of mango cultivars. Sci. Cult., 41: 385--386. Panse, V.C. and Sukhatme, P.V., 1967. Statistical methods for agriculture workers. I C A R New Delhi. Prasad, A., Singh, H. and Shukla, T.N., 1965. Present status of mango malformation disease. Indian Hortic., 22: 254--265. Rao, M.M., 1973. Studies on physiological and biochemical factors associated with the development, ripening and senescence of Pusa Seedless grapes. Thesis, IARI, New Delhi. Schlosser, E., 1971. Incidence of " b u n c h y t o p " on mango seedlings in West Pakistan. F A O Plant Protection Bull., 19: 41--42. Sen, P.K., Sen, S.K. and Guha, D., 1963. Carbohydrate and nitrogen content of mango shoots in relation to fruit-bud differentiation in them. Indian Agric., 7: 187--188.
44 Singh, L.B., 1960. Studies in the differentiation and development of fruit-buds in mango (Mangifera indica L. ). IV. Periodical changes in the chemical composition of shoots and their relation with fruit-bud differentiation. Hortic. Adv., 4: 48--59. Somogyi, M., 1945. A new reagent for determination of sugars. J. Biol. Chem., 160: 61--68. Summanwar, A.S., Raychaudhuri, S.P. and Phatak, S.C., 1966. Association of the fungus Fusarium moniliforme sheld. Ind. Phytopathol., 19: 227--228. Varma, A., Lele, V.C. and Goswami, B.K., 1974a. Mango malformation. Curt. Trends Plant Pathol., 196--208. Varma, A., Lele, V.C., Raychaudhuri, S.P., Ram, A. and Sang, A., 1974b. Mango malformation: a fungal disease. Phytopathol. Z., 79: 254--257.
37
B I O C H E M I C A L C H A N G E S A S S O C I A T E D WITH FLORAL MALFORMATION I N MANGO
R.M. PANDEY, M.M. RAO and R.A. PATHAK Division of Horticulture and Fruit Technology, Indian Agricultural Research Institute, New Delhi (India) (First received 11 November 1975; in revised form 18 May 1976)
ABSTRACT Pandey, R.M., Rao, M.M. and Pathak, R.A., 1977. Biochemical changes associated with floral malformation in mango. Scientia Hort., 6: 37--44. Changes in carbohydrate reserves and in total nitrogen, and the anatomy of healthy and malformed shoots of mango cultivars 'Dashehari' and 'Chausa' were followed before and after fruit-bud differentiation. Acid hydrolysable polysaccharides and total carbohydrates remained at higher levels in leaves, stems and panicles of malformed shoots as compared to healthy ones in both the cultivars. The total nitrogen did not show much change. Marked anatomical differences were noted in rachis of both types of panicles. The floral malformation was observed to be associated with the accumulation of excessive amounts of acid hydrolysable polysaccharides. Two possible ways of explaining the behaviour of malformed shoots have been suggested.
INTRODUCTION M a l f o r m a t i o n , w h i c h is o n e o f t h e m o s t serious p r o b l e m s o f m a n g o (Mangifera indica L.), causes g r e a t e c o n o m i c loss in India. It has b e e n divided i n t o t w o groups, v e g e t a t i v e a n d floral, d e p e n d i n g o n t h e p a r t s m a l f o r m e d . Floral m a l f o r m a t i o n , w h i c h is t h e s u b j e c t o f this s t u d y , is w i d e l y d i s t r i b u t e d all over India, a l t h o u g h t h e i n c i d e n c e is g r e a t e r in t h e N o r t h - W e s t t h a n in t h e N o r t h E a s t or S o u t h . A l t h o u g h this p r o b l e m e x i s t e d f o r a l o n g t i m e , t h e first des c r i p t i o n was m a d e b y Burns ( 1 9 1 0 ) in P o o n a (India). R e c e n t l y this m a l a d y has also b e e n r e p o r t e d f r o m P a k i s t a n ( K h a n a n d K h a n , 1 9 6 0 ) , Central A m e r i c a , M e x i c o a n d Israel (Malo a n d McMillan, 1972). T h e u n i q u e and visible s y m p t o m is a d e f o r m a t i o n o f t h e panicles w h i c h consists m a i n l y in a s h o r t e n i n g o f t h e p r i m a r y and s e c o n d a r y axes and t h i c k e n e d rachis, giving t h e f l o w e r s a c h a r a c t e r i s t i c c l u s t e r e d a p p e a r a n c e (Fig. 1 ). F l o w e r s o f m a l f o r m e d panicles are bigger t h a n n o r m a l a n d are m o s t l y male. A f f e c t e d panicles v e r y s e l d o m set fruit, a n d u l t i m a t e l y d r y up, r e m a i n i n g on t h e t r e e f o r m a n y m o n t h s as b l a c k masses o f d e a d tissue. It is v e r y c o m m o n
38
Fig.1. Healthy (left) and malformed (right) panicles of mango.
to see healthy and malformed panicles side by side or on the same branch. Another s y m p t o m , perhaps less evident~ is a swelling of the vegetative buds accompanied by a shortening of the internodes. When studying the 3 reviews on mango malformation (Prasad et al., 1965; Butani and Srivastava, 1973; Varma et al., 1974a), it is clear that the biochemical knowledge of this malady is poor. Most of the studies in the past have been of a general nature (Khan and Khan, 1960, 1962; Narsinham, 1959; Nirvan, 1953; Schlosser, 1971; Summanwar et al., 1966; Majumder et al., 1970). Only recently has some work been initiated on this aspect in particular (Pandey et al., 1973, 1974, 1975). In the present investigation an attempt has been made to find o u t the changes in the major constituents of leaves, stems and panicles and also in the anatomy of normal and malformed rachis of 'Dashehari' and 'Chausa', which are popular mango cultivars of Northern India. MATERIALS AND METHODS
The present investigation was carried o u t in the experimental orchard of the Indian Agricultural Research Institute, New Delhi, using 20-year-old trees of 2 commercial cultivars of mango, viz. 'Dashehari' and 'Chausa', grown under uniform cultural practices in 1973 and 1974. Averages of data for 2 years will be presented. Samples were collected at 2 different periods, before and after fruit-bud differentiation. Before fruit-bud differentiation malformed shoots were identified by the presence of scars. Samples of shoots (leaves and stems separately), carrying both healthy and malformed panicles were dried at 70 ° C
39
for 48 h and were analysed in triplicate for various constituents. Panicles were sampled when they were 7.5--10 cm long. Homogenate samples of leaves, stems and panicles were later extracted with ethanol, and carbohydrate fractions in the extract were separated by using ion-exchange columns (Rao~ 1973). Sugars were determined by the m e t h o d of Somogyi (1945), acid hydrolysable polysaccharides after Asana and Saini (1962) and total nitrogen by micro-kjeldahl. The procedure for chlorophyll determination was based on the method described by Arnon {1949). Anatomical differences between healthy and malformed panicles were studied by cutting the rachis with the aid of a microtome. The thickness of the rachis was measured by vernier callipers. The results of the study were statistically analysed by analysis of variance given by Panse and Sukhatme (1967). RESULTS
Changes in carbohydrate reserves and total nitrogen in different parts o f healthy and malformed shoots o f mango before fruit-bud differentiation. -From the data given in Table 1, it is clear that levels of reducing and total sugars were significantly higher in leaves of healthy shoots than in malformed ones in both cultivars. The higher content of non-reducing sugars observed in leaves of healthy shoots of both cultivars in comparison to malformed ones was statistically insignificant. Except for the non-reducing sugars in 'Dashehari', the difference recorded for the higher content of reducing, non-reducing and total sugars in stems of healthy shoots was insignificant as compared to malformed shoots in both cultivars. However, acid hydrolysable polysaccharides showed different patterns of accumulation; i.e. the amount remained at a significantly higher level in leaves and stems of malformed shoots than in healthy ones in both cultivars. The higher level of total carbohydrates in leaves and stems of malformed shoots as compared to the corresponding parts of healthy shoots was mainly due to an excess a m o u n t of acid hydrolysable polysaccharides. Similar results have been reported by Pandey et al. (1973) in the case of vegetative malformation of mango cultivar ' B o m b a y Green'. Unlike earlier findings pertaining to vegetative malformation, in the present case the levels of reducing and total sugars were higher in leaves and stems of healthy shoots than in malformed ones. With the exception of the stem of 'Dashehari', there was significantly higher content of N in leaves and stems of healthy shoots than in malformed ones in both cultivars. The carbohydrate and nitrogen ratios observed in leaves and stems of malformed shoots were significantly higher than in healthy ones in both cultivars. In addition, while a great difference was observed in the content of chlorophyll in healthy and malformed shoots of vegetative malformation (Pandey et al., 1973), practically no difference was observed in floral malformation. For example, the amounts of chlorophyll a, b and total in leaves of healthy shoots were found to be 6 mg, 12.6 mg and 18.6 mg per g.f.wt, respectively, while the corresponding values in the leaves of malformed shoots were 6 mg, 12.2 mg
40
and 18.2 mg per g.f.wt, respectively. This suggests that perhaps different mechanisms are involved in controlling the 2 types of malformation. Changes in carbohydrate reserves and total nitrogen in different parts of healthy and malformed shoots of mango after fruit-bud differentiation. -- The data pertaining to various constituents have been presented in Table 2. Comparing these data with those of Table 1 we see that, with the exception of nonreducing sugars, the levels of reducing and total sugars, total carbohydrates, total nitrogen and also C/N ratio declined in the leaves of healthy and malformed shoots of both cultivars after fruit-bud differentiation. Although decline in these constituents was noticed with age, the levels of acid hydrolysable polysaccharides and total carbohydrates remained at a significantly higher level in the leaves of malformed shoots than in healthy ones. While the levels of reducing and total sugars in the stems of healthy and malformed shoots declined, the levels of non-reducing sugars, acid hydrolysable polysaccharides and C/N ratio increased with age, i.e. after fruit-bud differentiation. One of the salient features of the present findings was that the level of total carbohydrates decreased in the leaves with a corresponding increase in the stems. This fact indicates the mobilization of carbohydrate from the site of synthesis to the site of utilization, perhaps for fruit-bud differentiation. Similar results have been reported by earlier workers (Singh, 1960; Sen et al., 1963). TABLE 1 A m o u n t o f various f r a c t i o n s o f c a r b o h y d r a t e s a n d t o t a l n i t r o g e n in d i f f e r e n t p a r t s o f h e a l t h y and m a l f o r m e d s h o o t s o f m a n g o b e f o r e f r u i t - b u d d i f f e r e n t i a t i o n , e x p r e s s e d as % d r y weight.
Constituents
Organ
'Dashehari' Healthy
'Chausa' Malformed
Healthy
Malformed
C.D. at 5% between 2 treatments means for a given cultivar
Reducing sugars
Leaf Stem
5.00 4.65
4.60 4.55
4.22 4.75
3.60 4.60
0.20 NS
Non-reducing
Leaf Stem
1.03 0.85
1.00 0.45
1.30 0.25
0.76 0.15
NS 0.11
Total sugars
Leaf Stem
6.03 5.50
5.60 5.00
5.50 5.00
4,38 4.75
0.31 NS
Acid hydrolyssble polysaccharides
Leaf Stem
12.60 20.25
12.96 21.60
13.14 16.77
14.40 18,90
0.27 0.14
Total
Leaf Stem
18.63 25.75
18.56 26.60
18.64 21.47
18.78 23,65
0.05 0.05
Total nitrogen
Leaf Stem
2.00 1.05
1.90 1.00
1.65 1.20
1.45 0.95
0.09 0.12
C/N ratio
Leaf Stem
9.32 24.52
9.76 26.60
11.30 17.89
12,95 24.69
0.12 0.06
sugars
carbohydrates
41
TABLE 2 A m o u n t o f various f r a c t i o n s o f c a r b o h y d r a t e and t o t a l n i t r o g e n in d i f f e r e n t p a r t s o f h e a l t h y and m a l f o r m e d s h o o t s o f m a n g o a f t e r f r u i t - b u d d i f f e r e n t i a t i o n , e x p r e s s e d as % d r y weight.
Constituents
Organ
'Dashehari' Healthy
'Chausa' Malformed
Healthy
Malformed
C.D. at 5% between 2 treatments means for a given cultivar
Reducing sugars
Leaf Stem Panicle
3.70 3.40 4.45
3.00 2.70 4.00
3.95 3.25 4.85
3.40 3.00 4.20
NS 0.21 NS
Non-reducing sugars
Leaf 'Stem Panicle
1.38 1.10 0.93
1.18 0.55 1.00
1.73 0.75 0.80
1.43 0.33 0.65
0.10 0.10 0.14
Total sugars
Leaf Stem Panicle
5.08 4.50 5.38
4.18 3.25 5.00
5.68 4.00 5.65
4.83 3.33 4.85
NS 0.19 NS
Acid hydrolysable polysaccharides
Leaf 10.26 Stem 25.20 Panicle 18.00
12.26 26.19 18.80
11.16 21.60 17.10
12.52 26.19 19.08
0.27 NS 0.14
Total carbohydrates
Leaf 15.34 Stem 29.70 Panicle 23.38
16.44 29.44 23.80
16.84 25.60 22.75
17.35 29.52 23.93
0.27 0.39 0.13
Total nitrogen
Leaf Stem Panicle
1.90 1.15 1.85
1.80 0.90 1.80
1.60 1.10 1.85
1.55 1.05 1.80
C/N ratio
Leaf 8.07 Stem 25.82 Panicle 12.63
9.13 32.71 13.22
10.52 23.27 12.30
11.19 28.11 13.29
NS NS NS 0.47 0.37 0.13
Although malformed stems contained the m a x i m u m a m o u n t of total carbohydrates and differentiated fruiting-buds, the same as healthy ones, t h e y did n o t develop normal panicles. The higher levels of reducing sugars and total sugars were statistically insignificant in healthy panicles as compared to malformed ones in both cultivars, while a reverse trend was observed for the c o n t e n t of acid hydrolysable polysaccharides and total carbohydrates. Here again, as with stems and leaves, the a m o u n t of acid hydrolysable polysaccharides remained at a higher level in malformed panicles. Anatomical changes in rachis o f healthy and malformed panicles o f mango. -As seen from Table 3, the thickness of the malformed rachis was approximately twice t h a t of the healthy one in both cultivars. Furthermore, the number of cells per unit area of cortex, xylem vessels and pith was llh times less in mal-
42
TABLE 3 Anatomical differences in the rachis of healthy and malformed panicles of mango. Organ
Measurement
'Dashehari' Healthy
'Chausa' Malformed
Healthy
Malformed
3.2
6.3
3.5
6.8
Epidermis Thickness (u)
13.4
24.1
17.4
28.1
Cortex
No. of cells per field
22
15
31
19
Size of cells length X breadth (u)
28.1 × 25,5
38.9 x 29.8
21.4 x 17.4
30.8 × 28.1
No. of cells per field
12
Size of cells length X breadth (u)
22.8 x 20.1
No. of cells per field
16
Size of cells length X breadth (u)
34.8 x 29.5
Rachis
Xylem vessels
Pith
Thickness (ram)
8
37.5 x 29.5
9
52.3 × 46.9
15
18.8 × 16.1
26
34.8 × 28.1
8
45.6 × 25.5
8
59.0 × 54.9
formed panicles than in healthy ones. The thickness of rachis and the smaller number of cells/field in the rachis of malformed panicles were a function of cell size, which was greater in the case of malformed rachis. DISCUSSION
Observed data indicated that the level of acid hydrolysable polysaccharides which is favourable for the induction of floral primordia (Singh, 1960) was higher in leaves, stems and panicles of malformed shoots than in those of healthy ones before fruit-bud differentiation. Their level remained higher even after fruit-bud differentiation. This brings out the possibility that perhaps acid hydrolysable polysaccharides in malformed panicles are not being hydrolysed into simple sugars in the same manner as they are hydrolysed in normal panicles~ to meet the energy requirement of the panicles for their normal development. Therefore, although fruit-bud differentiation in 2 types of panicles takes place simultaneously, the normal development of the panicles borne on malformed shoots is suppressed. On the basis of the above facts, 2 possibilities have been suggested to explain the peculiar behaviour of malformed panicles. Firstly, there may be certain pa-
43
thogens involved in causing the disturbances in the metabolism (Varma et al., 1974b). Secondly, there may be imbalance between growth promoters and growth inhibitors, which are in some way linked with this phenomenon (Pandey et al., 1974). Since this malady can be controlled to a great extent by spraying with ~-napthyleneacetic acid (200 p.p.m.) (Majumder et al., 1970), the second possibility seems to be more plausible. ACKNOWLEDGEMENTS
Grateful thanks are due to Dr. R.N. Singh, Head Division of Horticulture and Fruit Technology, Indian Agricultural Research Institute~ New Delhi, for providing facilities. REFERENCES Arnon, D.I., 1949. Copper enzymes in isolated chloroplasts. Plant Physiol., 24: 1--15. Asana, R.D. and Saini, A.D., 1962. Studies in physiological analysis of yield. V. Grain development in wheat in relation to temperature, soil moisture and age in sugar content of stem and in photosynthetic surface. Ind. J. Plant Physiol., 5: 128--171. Burns, W., 1910. A c o m m o n malformation of mango inflorescence. Poona Agric. Coll. Mag.~ 2: 38--39. Butani, and Srivastava, R.P., 1973. La "Malformation" du manguier. Fruits, 28: 389--395. Khan, M.D. and Khan, A.H., 1960. Studies on malformation of mango inflorescence in West Pakistan. Punjab Fruit J., 23: 247--258. Khan, M.D. and Khan, A.H., 1962. Relation of growth to malformation of inflorescence in mango. West Pak. J. Agric. Res., 1: 51--63. Majumder, P.K., Sinha, G.C. and Singh, R.N., 1970. Effect of exogenous application of napthyleneacetic acid on mango (Mangifera indica L. ) malformation. Indian J. Hortic., 27: 130--131. Malo, S.E. and McMillan, Jr., 1972. A disease of Mangifera indica L. in Florida similar to mango malformation. Proc. F1. State Hortic. Soc., 85: 264--268. Narsinham, M.J., 1959. Control of mango (inflorescence) malformation disease. Curr. Sci., 28: 254--257. Nirvan, R.S., 1953. Bunchy top of young mango seedlings. Sci. Cult., 18: 333--334. Pandey, R.M., Sinha, G.C., Singh, R.N. and Majumder, P.K., 1973. Some biochemical aspects of vegetative malformation in mango (M. indica L. ) I. Carbohydrate reserves and nitrogenous fractions. Indian J. Hortic., 3: 475--480. Pandey, R.M., Rathore, D.S. and Singh, R.N., 1974. Hormonal regulation of mango malformation. Curr. Sci., 43: 694---695. Pandey, R.M., Singh, R.N. and Rao, M.M., 1975. Nucleic acid and protein levels in healthy and malformed panicles of mango cultivars. Sci. Cult., 41: 385--386. Panse, V.C. and Sukhatme, P.V., 1967. Statistical methods for agriculture workers. I C A R New Delhi. Prasad, A., Singh, H. and Shukla, T.N., 1965. Present status of mango malformation disease. Indian Hortic., 22: 254--265. Rao, M.M., 1973. Studies on physiological and biochemical factors associated with the development, ripening and senescence of Pusa Seedless grapes. Thesis, IARI, New Delhi. Schlosser, E., 1971. Incidence of " b u n c h y t o p " on mango seedlings in West Pakistan. F A O Plant Protection Bull., 19: 41--42. Sen, P.K., Sen, S.K. and Guha, D., 1963. Carbohydrate and nitrogen content of mango shoots in relation to fruit-bud differentiation in them. Indian Agric., 7: 187--188.
44 Singh, L.B., 1960. Studies in the differentiation and development of fruit-buds in mango (Mangifera indica L. ). IV. Periodical changes in the chemical composition of shoots and their relation with fruit-bud differentiation. Hortic. Adv., 4: 48--59. Somogyi, M., 1945. A new reagent for determination of sugars. J. Biol. Chem., 160: 61--68. Summanwar, A.S., Raychaudhuri, S.P. and Phatak, S.C., 1966. Association of the fungus Fusarium moniliforme sheld. Ind. Phytopathol., 19: 227--228. Varma, A., Lele, V.C. and Goswami, B.K., 1974a. Mango malformation. Curt. Trends Plant Pathol., 196--208. Varma, A., Lele, V.C., Raychaudhuri, S.P., Ram, A. and Sang, A., 1974b. Mango malformation: a fungal disease. Phytopathol. Z., 79: 254--257.