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Sweet-potato productivity as affected by recurrent use of vines as planting-material
Scientia Horticulturae, 20 (1983) 319--322
319
Elsevier Science Publishers B.V., Amsterdam - - P r i n t e d in The Netherlands
SWEET-POTATO PRODUCTIVITY AS A F F E C T E D BY R E C U R R E N T USE OF VINES AS PLANTING-MATERIAL
P.K. RAY, S. MISHRA and S.S. MISHRA
Department of Horticulture, Rajendra Agricultural University, Campus-Dholi-843121, Muzaffarpur, Bihar (India) (Accepted for publication 10 December 1982)
ABSTRACT Ray, P.K., Mishra, S. and Mishra, S.S., 1983. Sweet-potato productivity as affected by recurrent use of vines as planting-material. Scientia Hortic., 20: 319--322. Yield performances of apical shoot cuttings of sweet potato (Ipomoea batatas) obtained from crops raised 2 or 4 times recurrently through vines, were compared with those obtained from tubers. The recurrent use of vines as planting-material did not show any marked variation in market-grade tuber yield, but it significantly decreased vine yield and increased weevil infestation in tubers. Cultivars 'Cross-4', 'V-35' and 'RS-5' differed significantly in performance. Keywords: Cylas formicarius ; Ipomoea batatas, sweet potato. INTRODUCTION
In North India, where 2, and in some parts even 3, crops of sweet potato are grown during autumn, spring and the rainy seasons, vines from one crop are used for planting the next crop. This practice is also prevalent in other parts of the tropics and sub-tropics (Onwueme, 1978). Available reports (Anonymous, 1962; Singh, 1964; Kay, 1973) indicate that the use of such recurrent vines results in progressively lower yields. Since these reports do not quantify the reduction in yield and quality of marketable produce, the present investigation was undertaken to ascertain the extent of yield decline and infestation of weevil (Cylas formicarius Fb.) in 3 sweet-potato cultivars b y repeated use of vines for planting. MATERIALS AND METHODS
The experiment was c o n d u c t e d during the autumns of 1979 and 1980 at the experimental farm of the College of Agriculture, Dholi, located at longitude 85.4°E, latitude 25.5°N and altitude 52 m. The soil was a sandy loam with pH 8, total N 0.038%, available P 8.6 kg ha 1 and available K 35.0 kg ha -~. 0304-4238/83/$03.00
© 1983 Elsevier Science Publishers B.V.
320
The cultivars were 'Cross-4', 'V-35' and 'RS-5'. The treatments were: (1) vines obtained from tubers planted in July 1979/1980 constituting fresh planting-material; (2) vines obtained from tubers planted in July 1978/1979 constituting 2seasons (times)-old recurrent planting-material; (3) vines obtained from tubers planted in July 1977/1978 constituting 4seasons (times)-old recurrent planting-material. The vines obtained in the years 1977--1979 were maintained by growing 2 crops per year using vine cuttings as planting-material until the crop for the experiment was planted. A randomised block design was followed with a total of 9 treatment combinations (3 types of vine × 3 cultivars). All the treatments were replicated 3 times. The net size of a plot, designed to accommodate 100 plants per treatment, was 3 m × 3 m. The vines were planted 30 cm apart both ways in the second week of September. The crop was managed uniformly with rec o m m e n d e d agro-practices. The manurial dose applied consisted of 10 tonnes of farm-yard manure, 60 kg N, 40 kg P2Os and 40 kg K20 per hectare. Harvesting was done 120 days after planting, and data were collected on market-grade tuber yield, vine yield and weevil infestation. RESULTS AND DISCUSSION
The effect of recurrent use of vines on market-grade fresh weight of tubers at harvest was insignificant (Table I). The highest mean yield was obtained from freshly raised vines. The difference in yield due to cultivar was significant, with the highest yield from 'Cross-4'. Similarly, the interaction effect of vine types and cultivars with respect to tuber yield was significant, and the combination of 'Cross-4' grown from fresh vines produced the highest yield. The highest mean value of vine yield was obtained when fresh vines were used for planting. This proved significantly superior to the other treatments. Considerable variation was noticed among the cultivars with regard to vine yield, 'Cross-4' giving the highest value. Interaction values indicated the marked superiority of the combination 'Cross-4' raised freshly from tubers. The variation in yield of tuber and vine due to different treatments can be attributed to the number of roots produced for establishment of the plant at an early age. Since plants grown from vines obtained afresh were observed to be more vigorous, with greater crop growth rate, they produced the highest yields. These findings corroborate the results of Enyi (1977), who reported a positive and significant correlation between crop growth rate and the final total dry weight diverted into the tubers. Weevil infestation was maximum when vines were obtained from a crop raised recurrently 4 times (Table I). A decrease in the number of recurrent uses of a vine correspondingly decreased the degree of weevil infestation in the tubers. The use of fresh vines registered the minimum weevil incidence in
L.S.D. (P = 0 . 0 5 ) For treatment F o r cultivar For treatment x cultivar
(1) F r e s h l y raised (2) Raised r e c u r r e n t l y twice (3) Raised r e c u r r e n t l y 4 t i m e s Mean
T r e a t m e n t o f vines
35.85 31.35 30.91 32.70
31.88 30.37 29.50 30.58
33.43 30.36 30.83 31.54
NS 0.78 1.25
33.72 30.70 30.41 31.61
19.93 17.72 19.00 18.90
18.37 17.45 16.40 17.41
'V-35'
'Cross-4'
'RS-5' Mean
'Cross-4'
'V-35'
V i n e yield ( t o n n e s h a -1 )
M a r k e t a b l e t u b e r yield ( t o n n e s h a -1 )
E f f e c t o f r e c u r r e n t use o f vines o n s w e e t - p o t a t o p r o d u c t i v i t y ( m e a n s o f 2 years)
TABLE I
18.96 17.72 17.87 18.18
0.49 0.47 0.79
19.09 17.64 17.76 18.16
'RS-5' Mean
23.83 25.36 30.56 26.58
'Cross-4'
21.24 21.78 24.17 22.40
'V-35'
16.75 18.93 19.62 18.43
0.37 0.37 0.60
20.61 22.02 24.78 22.47
'RS-5' Mean
Weevil i n f e s t a t i o n (%)
b-a
322 all cases. The differences in percentage of infestation due to vine type or cultivar were highly significant. 'Cross-4' was the most susceptible, while 'RS-5' exhibited some tolerance. Furthermore, growing 'RS-5' by planting fresh vines proved to be the best treatment combination, resulting in the lowest weevil damage. Using vines recurrently for raising the sweet-potato crop possibly added to the perpetuation, multiplication and build-up of the sweet-potato weevil, in particular, and also of some other factors that caused productivity decline and culminated in lowered market-grade tuber yield of different cultivars in succeeding years.
REFERENCES Anonymous, 1962. Sweet Potato -- A Good Food Crop. Information Bull. 43, Directorate of Extension, Ministry of Food and Agriculture,N e w Delhi, pp. 3--4. Enyi, B.A.C., 1977. Analysis of growth and tuber yield in sweet potato (Ipomoea batatas) cultivars.J. Agric. Sci.,88: 421---430. Kay, D.E., 1973. Crop and Product Digest 2: Root Crops. Tropical Products Institute, London, pp. 146--150. Onwueme, I.C.,1978. Tropical Tuber Crops. Wiley, N e w York, pp. 175--178. Singh, H.B., 1964. Cultivation of Sweet Potato. Farm Bull. 4, ICAR, N e w Delhi, pp. 13--14.
319
Elsevier Science Publishers B.V., Amsterdam - - P r i n t e d in The Netherlands
SWEET-POTATO PRODUCTIVITY AS A F F E C T E D BY R E C U R R E N T USE OF VINES AS PLANTING-MATERIAL
P.K. RAY, S. MISHRA and S.S. MISHRA
Department of Horticulture, Rajendra Agricultural University, Campus-Dholi-843121, Muzaffarpur, Bihar (India) (Accepted for publication 10 December 1982)
ABSTRACT Ray, P.K., Mishra, S. and Mishra, S.S., 1983. Sweet-potato productivity as affected by recurrent use of vines as planting-material. Scientia Hortic., 20: 319--322. Yield performances of apical shoot cuttings of sweet potato (Ipomoea batatas) obtained from crops raised 2 or 4 times recurrently through vines, were compared with those obtained from tubers. The recurrent use of vines as planting-material did not show any marked variation in market-grade tuber yield, but it significantly decreased vine yield and increased weevil infestation in tubers. Cultivars 'Cross-4', 'V-35' and 'RS-5' differed significantly in performance. Keywords: Cylas formicarius ; Ipomoea batatas, sweet potato. INTRODUCTION
In North India, where 2, and in some parts even 3, crops of sweet potato are grown during autumn, spring and the rainy seasons, vines from one crop are used for planting the next crop. This practice is also prevalent in other parts of the tropics and sub-tropics (Onwueme, 1978). Available reports (Anonymous, 1962; Singh, 1964; Kay, 1973) indicate that the use of such recurrent vines results in progressively lower yields. Since these reports do not quantify the reduction in yield and quality of marketable produce, the present investigation was undertaken to ascertain the extent of yield decline and infestation of weevil (Cylas formicarius Fb.) in 3 sweet-potato cultivars b y repeated use of vines for planting. MATERIALS AND METHODS
The experiment was c o n d u c t e d during the autumns of 1979 and 1980 at the experimental farm of the College of Agriculture, Dholi, located at longitude 85.4°E, latitude 25.5°N and altitude 52 m. The soil was a sandy loam with pH 8, total N 0.038%, available P 8.6 kg ha 1 and available K 35.0 kg ha -~. 0304-4238/83/$03.00
© 1983 Elsevier Science Publishers B.V.
320
The cultivars were 'Cross-4', 'V-35' and 'RS-5'. The treatments were: (1) vines obtained from tubers planted in July 1979/1980 constituting fresh planting-material; (2) vines obtained from tubers planted in July 1978/1979 constituting 2seasons (times)-old recurrent planting-material; (3) vines obtained from tubers planted in July 1977/1978 constituting 4seasons (times)-old recurrent planting-material. The vines obtained in the years 1977--1979 were maintained by growing 2 crops per year using vine cuttings as planting-material until the crop for the experiment was planted. A randomised block design was followed with a total of 9 treatment combinations (3 types of vine × 3 cultivars). All the treatments were replicated 3 times. The net size of a plot, designed to accommodate 100 plants per treatment, was 3 m × 3 m. The vines were planted 30 cm apart both ways in the second week of September. The crop was managed uniformly with rec o m m e n d e d agro-practices. The manurial dose applied consisted of 10 tonnes of farm-yard manure, 60 kg N, 40 kg P2Os and 40 kg K20 per hectare. Harvesting was done 120 days after planting, and data were collected on market-grade tuber yield, vine yield and weevil infestation. RESULTS AND DISCUSSION
The effect of recurrent use of vines on market-grade fresh weight of tubers at harvest was insignificant (Table I). The highest mean yield was obtained from freshly raised vines. The difference in yield due to cultivar was significant, with the highest yield from 'Cross-4'. Similarly, the interaction effect of vine types and cultivars with respect to tuber yield was significant, and the combination of 'Cross-4' grown from fresh vines produced the highest yield. The highest mean value of vine yield was obtained when fresh vines were used for planting. This proved significantly superior to the other treatments. Considerable variation was noticed among the cultivars with regard to vine yield, 'Cross-4' giving the highest value. Interaction values indicated the marked superiority of the combination 'Cross-4' raised freshly from tubers. The variation in yield of tuber and vine due to different treatments can be attributed to the number of roots produced for establishment of the plant at an early age. Since plants grown from vines obtained afresh were observed to be more vigorous, with greater crop growth rate, they produced the highest yields. These findings corroborate the results of Enyi (1977), who reported a positive and significant correlation between crop growth rate and the final total dry weight diverted into the tubers. Weevil infestation was maximum when vines were obtained from a crop raised recurrently 4 times (Table I). A decrease in the number of recurrent uses of a vine correspondingly decreased the degree of weevil infestation in the tubers. The use of fresh vines registered the minimum weevil incidence in
L.S.D. (P = 0 . 0 5 ) For treatment F o r cultivar For treatment x cultivar
(1) F r e s h l y raised (2) Raised r e c u r r e n t l y twice (3) Raised r e c u r r e n t l y 4 t i m e s Mean
T r e a t m e n t o f vines
35.85 31.35 30.91 32.70
31.88 30.37 29.50 30.58
33.43 30.36 30.83 31.54
NS 0.78 1.25
33.72 30.70 30.41 31.61
19.93 17.72 19.00 18.90
18.37 17.45 16.40 17.41
'V-35'
'Cross-4'
'RS-5' Mean
'Cross-4'
'V-35'
V i n e yield ( t o n n e s h a -1 )
M a r k e t a b l e t u b e r yield ( t o n n e s h a -1 )
E f f e c t o f r e c u r r e n t use o f vines o n s w e e t - p o t a t o p r o d u c t i v i t y ( m e a n s o f 2 years)
TABLE I
18.96 17.72 17.87 18.18
0.49 0.47 0.79
19.09 17.64 17.76 18.16
'RS-5' Mean
23.83 25.36 30.56 26.58
'Cross-4'
21.24 21.78 24.17 22.40
'V-35'
16.75 18.93 19.62 18.43
0.37 0.37 0.60
20.61 22.02 24.78 22.47
'RS-5' Mean
Weevil i n f e s t a t i o n (%)
b-a
322 all cases. The differences in percentage of infestation due to vine type or cultivar were highly significant. 'Cross-4' was the most susceptible, while 'RS-5' exhibited some tolerance. Furthermore, growing 'RS-5' by planting fresh vines proved to be the best treatment combination, resulting in the lowest weevil damage. Using vines recurrently for raising the sweet-potato crop possibly added to the perpetuation, multiplication and build-up of the sweet-potato weevil, in particular, and also of some other factors that caused productivity decline and culminated in lowered market-grade tuber yield of different cultivars in succeeding years.
REFERENCES Anonymous, 1962. Sweet Potato -- A Good Food Crop. Information Bull. 43, Directorate of Extension, Ministry of Food and Agriculture,N e w Delhi, pp. 3--4. Enyi, B.A.C., 1977. Analysis of growth and tuber yield in sweet potato (Ipomoea batatas) cultivars.J. Agric. Sci.,88: 421---430. Kay, D.E., 1973. Crop and Product Digest 2: Root Crops. Tropical Products Institute, London, pp. 146--150. Onwueme, I.C.,1978. Tropical Tuber Crops. Wiley, N e w York, pp. 175--178. Singh, H.B., 1964. Cultivation of Sweet Potato. Farm Bull. 4, ICAR, N e w Delhi, pp. 13--14.