Indian J. Plant Physiol. , 2003 (Special Issue) pp. 85-90

METHODS OF LITTLE TUBER PRODUCTION ON PHYSIOLOGICALLY OLD MOTHER TUBERS IN POTATO (SOLANUM TUBEROSUM L.)

VIJAY PAULl' AND R. EZE KIEL 2

'Central Potato Research Institute-Campus, Modipuram , Meerut 250 110, U,P, 2Central Potato Research Institute, Shimla 17 1001 , H.P.

SUMMARY

Potato (Solanum tuberosum L.) tubers when stored for a long time become physiologically old and produce little tubers. This could be the result of the tubers naturally becoming old or due to hastening of their life cycle by stor age conditions. In view of the scope and possibility of using little tubers as propa­gation material, four methods for little tuber production were developed and tested for their efficiency in five varieties of potato during 1996 to 1999. The methods were: (i) low temperature (2-4 °C) exposure followed by desprouting during stor age at 25°C, (ii) low temperature (2-4 °C) exposure followed by sprouting at 25°C and low temperature exposure at 6 °C and subsequent storage at 20 °C, (iii) repeated desprouting during storage at 20 °C, and (iv) low temperature (2-4 °C) exposure followed by desprouting during storage at 18°C. Maximum number of little tubers per mother tuber (19-46 , depending on the variety) was produced by method 2 for all the var ieti es except for Kufri Sindhuri. In terms of average weight of little tuber, method 1 yielded bolder (0.25-0.50 g) little tubers. Keeping in view the practical importance of bolder little tubers for direct planting in the field, method 1 was found more suitable. Fur­ther research is needed to increase the number of little tubers weighing more than 0.5g and to decrease the time taken for the formation of little tubers for effective commercial exploitation of little tubers as propagation material

Key words: Little potato tuber, physiological ageing, propagation, seed tuber, Solanum tuberosum

INTRODUCTION evaluation studies (Paul and Ezekie l 2003), clearl y demonstrated that the perfor mance of little tubers (0.5­For the first time litt le potato tuber forma tion on long 1.0 g) planted at half the normal spacing i.e. 60 x 10 cm stored tubers was reported by Varies ( 1878). Condi tions were as goo d as normal seed tubers (40-60 g). In potato affecting their formation were described by Schreven production system, timely, adequate and continuous supply (1956) and Dimalla and van Staden (1977) . Physiological of high quality healthy (especially virus free) seed tubers age of mo ther tuber (Bodleander 1964, Burton 1989) and are the basic requi rements (Davis 1996). Since production low temp erature exposure (Tyagi 1981, Hiller et at. 1985) of little tubers is done under controlled conditions avoiding were reported to be important determinants for indu ction exposure to virus transmittin g vectors , degeneration due and produ ction of little tubers. Ezekiel (1997) produced to viral diseases is prevented . Keepin g in view the scope little tubers on physiologically old seed tubers either by and possibili ty of using littl e tubers as an alternative subjecting spro uted tubers to low tem perature treatment prop agat ion mat e ri al , fact or s affec ti ng littl e tuber or by repeated desprouting of tubers stored at 20 °C. Field produ ction (Ezekiel et at. 2000, Paul and Ezekiel 2002a ) and the dormancy behaviour of littl e tuber (PallI and*Corresponding author; e-mail: vijay_pauUari@yahoo.com

Present address : Divi sion of Plant Physiology, IAR!, New Delhi Ezekiel 2002b) were studied . The present investigation

1100 12 was taken Lip to develop differe nt methods of litt le tuber

Indian J. Plant Physiol.. 2003 (Specia l Issue) pp . 85-90 85

VIJAY PAUL AND R. EZEKIEL

production and to evaluate the efficiency of each method in order to recommend most efficient method for the production of little tubers.

MATERIALS AND METHODS

Healthy potato crops of three white tuber producing varieties viz. Kufri Chandramukhi, Kufri Jyoti, Kufri Bahar and two red tuber producing varieties Kufri Lalima and Kufri Sindhuri were grown during 1995-1999 at CPRIC, Modipuram. Seed tubers were planted during mid of October and fertilizers were applied @ 150 kg N, 80 kg

P20) and 100 kg K20/ha and recommended cultural practices for the region were followed. Harvesting was done when the crop was fully matured and tubers weighing 75-120 g were used in the experiments.

In order to develop an efficient method for little tuber induction and production, four methods for little tuber production were developed and tested for their efficiency. The four methods developed are described in Table 1. For each method and variety, 200 mother tubers were taken just after harvest and treated with Dithane M-45 (dipped for 10 minutes in 0.3% solution) to prevent fungal

Table 1. Different methods developed for little potato tuber production

Steps Method 1 Method 2 Method 3 Method 4 Low temperature (2-4°C) Low tempera ture (2-4°C) Repeated desprouting Low temperature (2-4°C)

exposure followed by exposure followed by at 20°C (1997-1998) exposure followed by

desprouting at sprouting at 25°C, desprouting at 18°C

25°C (1995-1996) and low temperature (6°C) (1998-1999)

exposure and subsequent storage

at 20°C (1995- I996)

1. Tubers were harvested on Tubers were harvested Tubers were harvested on Tubers were harvested on 14 February, 1995 and kept on 15 February, 1995 and 15 February, 1997 and kept 16 January 1998 and kept

at room temperature before kept at room temperature at room temperature before at room temperature before

sending to cold store before sending to cold storing at 20°C on sending to cold store on

(2-4°C) on 15 March for store (2-4°C) on 22 March 20 March 1997 7 March for 6Y2 months

6months storage (up to 13 for 6 months storage storage (up to 5 October, 1998)

September, 1995) (up to 20 September, 1995)

2. Tubers were removed from Tubers were taken out of Tubers were desprouted Tubers were then shifted to 18°C

cold store and presprouted cold store and presprouted thrice on and desprouted thrice on

at room temperature (Min. in dark at 25°C for 60 days I. 19 May, 1997 1. 31 October, 1998

17.4°C and Max. 30. 1°C) (21 September to 2. 18 June, 1997 2. 30 November, 1998

for one month i.e. till 20 November, 1995) 3.20 July, 1997 3.28 December, 1998

15 October, 1995

3. Tubers were then stored Sprouted mother tubers were Little tubers were initiated * Little tubers were initiated* at 25°C and desprouted stored at 6°C for 60 days by first and second week during third week of January

twice on (2 1 November 1995 to of November, 1997

1. 14 November, 1995 20 January, 1996) for inducing

2. 12 December 1995 little tuber formation

4. Little tubers were initiated* in Induced mother tubers were Little tubers were harvested Three harvesting of little the last week of December then shifted to 20°C for twice on tubers were done on

little tuber initiation * I. 20 January, 1998 I. 20 February, 1999 2. 5 March, 1998 2. 15 March, 1999

3. 25 March, 1999

5. Little tubers were harvested Little tubers were harvested twice on twice on

l. 30 January, 1996 l. 25 January, 1996 2. 20 March, 1996 2. 28 March , 1996

*When 10 % of mother tubers showed presence of little tubers, it was taken as the time of little tuber initiation.

Indian J. Plant Phvsiol.. 2003 (Special Issue) pp. 85-90 86

--

METH ODS OF LITTL E TUBER PRODUCTION IN POTATO

infect ion during storage. Different temperatures used are presented in Table 1 and the RH was maintain ed at 80 ±

5%. Tubers we re sto red in dark. At harvest, number and we ight of littl e tubers produced were recorded .

RESULTS AND DISCUSSION

Stages of little tube r production and the harv ested little tubers have been described earl ier (Pa ul and Ezekiel 2003). Maximum number of little tubers for all, except variety Kufri Sindhuri, was produced by meth od 2 (Fig . 1). Ln Kufri Sin dhuri, maximum littl e tubers (86) were produced by method 3. Within a meth od and amo ng different meth ods, different varieties behaved differentl y for the number of littl e tubers produced per mother tuber (Fig. 1). In terms of average we ight of little tuber, meth od I yielded bold er little tubers with weight from 0.2 5 to 0.50 g (Fig. 2). Meth od s 2 and 3 produ ced equiva len t number of little tubers with an average of 36 .8 and 37 .2, respe cti vely . Thi s wa s followed by mean va lue of 14.2 and 7.0 fo r method s 1 and 4 respecti vely (Fig. 3) . From the dat e of harv est of mother tub ers to the tim e of little tuber initiat ion , me thods 1 and 3 took 10 and 9 months respectiv ely and for methods 2 and 4 time peri od was I L months (Fig . 3) . Irrespect ive of the method fo llowed, it

90

8 0 ~

Q)

.0 7 0 :::J-~

Q) 60£ 0 E 50 ~

Q)

.0 4 0 :::J

~- 30--0 2 0 0 Z

10

0

took 13 to 14 months from the date of harvest of moth er tuber to the last harvestin g of littl e tubers.

Little tuber production efficiency was better for method 1 in co mpariso n with method 4 (Fig . I ) . Th ese two methods differed in the incubation temperature, during storage of moth er tubers. Higher temperature of 25 DC was used fo r meth od 1 in contrast with 18 DC for meth od 4 (Table I). Better efficiency of meth od 1 might be due to higher rate of physiological agein g at higher storage temperature. These co nditions might have favo ured better partiti onin g of assimilate from mother tuber to little tubers and as a result the littl e tubers produced from method I were of bold er size with average weight of O.!J g with a ran ge of 0.25-0.50 g (Fig. 3) . Conditions, which acce lerate physiological ageing such as storage under warm condition has been reported by Hiller et al. ( 1985) and Ezekiel et aZ. (2000).

The initiation of little tuber appears to be the culmination of a devel opmental sequence leading to tub er izat ion (Burton 1989). Thi s happ en s when storage co nditions hasten the life cycle of mother tuber. Our experimental conditions such as low temperature exposure and darkness are reported to decrease gibberellins (Railton and Wareing 1973, Krauss and Marschn er 1982) . Absci sic ac id (ABA)

[[I Kufri Chandramukhi

~ Kufri Jyoti

~ Kufri Bahar

[[I Kufri Lalima

mKufri Sindhuri

2 3 4

Method for little tuber production

(for detai ls see Tab le 1)

Fig. 1. Numb er of little tubers produced by four different methods in five cultivars of pota to

Indian J . Plan t Physiol ., 2003 (Spec ial Issue) pp. 85-90 87

VIJAY PAUL AND R. EZEKIEL

0.6

.g 0.5

<1l .c .2 0.4 ~--o 0.3 .... ..c Ol

~ 0.2 <1l Ol ~ ~ 0.1 «

o

mI Kufri Chandramukhi

~ Kufri Jyoti

~ Kufri Bahar

iii Kufri Lalima

mKufri Sindhuri

234 Method for little tuber production

(for details sec Table 1)

Fig. 2. Average weight of little tubers produced from different methods in five cultivars of potato

50

45

40en s: c 0 35:2 "0 c ell 30 l!! "0 Ql ~ ..c .2 ::l

0­25

Ql ~ ...... 20

'0 .... Ql ..c 15 E ::l Z 10

5

0

~ Months required for initiation of little tuber

~ Average num ber of little tubers produced/m other tuber mI Average weight of little tuber (g)

2 3 4 Method for little tuber production

(for details see Table 1)

0.50

0.45

0.40

.9 ....0.35 Ql ..c ::l-0.30 Ql

'00.25 :c Ol 'Qj

0.20 :;: Ql Ol

0.15 ~ Ql> «

0.10

0.05

0.00

Fig. 3. Effect of different methods on initiation and production of little tube. Data represent the mean values for five vareities of potato

Indian J. Plant Physi ol .. 2003 (Special Issue) pp. 85-90 88

METHODS OF LITTLE TUBER PROD UCTION IN POTATO

is known to increase under conditions of stress such as, low temperature, desiccation, wounding (as caused by desprouting in the pre sent investigation) and ageing (Railton and Wareing 1973, Krau ss and Marschner 1982, Hiller et al. 1985, van Berkel et al. 1994). Thus, the conditions as follow ed for thi s study such as low temperature (2-4 DC) exposure, incubation at higher temperature (18 , 20 or 25 DC) and repeated desprouting (2 to 3 times) to facilitate rapid physiological ageing might have altered the balance of endogenous hormones (GA, ABA and cytokinins) of mother tuber. This change might have led to indu ction and production of little tubers on physiologically old moth er tubers. Ezekiel et al . (2000) suggested low GA/ABA ratio for little tuber induction/ production. It is therefore suggested that both ageing and low temperature conditions might have led to the same effect i.e. lowering the level of GA and thus cau sed initiation oflittle tubers. Additionally,higher level of abscisic acid in mother tuber undergoing ageing (Burton et al . 1992) may also be contributing for the initiation and development of little tubers. Thus, the system of little tuber induction and production appeared to be similar to that of tuberization under field conditions.

The study with smaller grade of little tubers i.e. 0.3­0.5 g as planting material for varieties Kufri Bahar and Kufri Sindhuri also performed at par with normal seed potato in terms of total yield although number of small size tubers produced were significantly high er (Paul and Ezekiel 2003). These studies therefore strongly indicated the practical usefulness of little tubers with average weight of 0.4 g as obtained from method I in the pre sent investigations. Thi s material can be directly planted in the field after presprouting. The present schedule oflittle tuber production system indicated that harvested little tubers in the plain s or the hills could be used for planting only in the second crop season from the time of harve sting of mother tubers. On the other hand , harvesting of little tubers could be completed in March-April or September-October in the plains and the hills respectively and thus the little tubers produced in the plains could be used for planting in the hills during May-June and in plain s during October­November after dormancy breaking treatment. To make this system commercially feasible, viable and to be fitted in normal potato cropping schedule, efforts should be made to enhance the number of little tubers produced having

Indi an J. Plant Physiol. , 2003 (Special Issue) pp. 85-90

weight of 0.4 to 0.6 g, at least five times the present rate of multipli cation and to shorten the total time taken to 6 to 7 months so that the produced little tubers could be utilized in the following potato season just after their harvest.

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of seco nd growth in potato tubers. Eur: Potato J. 7: 57-71.

Burton , w.G. ( 1989). Th e Potato . Longman, Singapore.

Burton , w. G., van Es, A. and Harmans, K.J. ( 1992). The physics and physiology of storage. In: P.M. Haris (ed.), The Potato Cro p, pp. 608-727. Chapman and Hall , London .

Davis, H.V. (1996) . Recent developm ents in our knowledge of potato transgenic biology. Potato Res. 39: 4 11-427.

Dim all a, G.G. and van Staden J. ( 1977) . Effec t of eth ylene on the endog eno us cyt ok inin and g ibbere ll in lev el s in tuberizing potatoes. Plant Physiol. 60 : 2 18-22 1.

Ezekiel, R. (I997). Produ ctiun of minitubers on physiologically old mother tub ers of pot ato in storage . In: Abstra ct s, Nat iona l Seminar on Plant Physiology for Susta inable Agriculture, March 19-21, IARI , New Delhi .

Ezekiel, R ., Paul , v., Sin gh , B ., Peshin , A. and Shekhawat , G.S. (2000) . Effec t of low temperatu re, desprout ing and gibbere llic ac id tr eatm ent on little tub er fo rma tion on pot atoes dur ing storage . J. Indian Potato Assoc. 27: 13-23.

Hill er , I.K ., Kaller , C.D. and Thomton , R.E. (I985). Physiological disord ers of potato tubers. In: P.H. Li (ed.), Potato Physiolo gy, pp. 389-4 55. Academi c Press, Orlando.

Krauss, A. and Marschner , H. ( 1982) . Influen ce of nitrogen , day length and temp erature on content of gibbere llic and abscis ic acid and on tuberization in potato plant. Potato Res. 25: 13-21.

Paul , V. and Ezekiel, R. (2002a). Effect of low temp erature exposure on the efficiency of little tuber production from physiologically old mother tubers. In: S.M. Paul Khur ana, G.S. Shekhawat, S.K. Pandey and B.P. Sin gh (e ds.) , Potato, Gl ub al Research and Devel opment (Vol. II). Proceed ing of Gl obal Co nfe rence on Pot ato . December 6- 11, 1999 , New Delhi , pp. 111 6-1 120 . Malhotra Publi shing House, New Delhi .

Paul, V. and Ezekiel, R. (2002b). Dormancy and sprout gro wth in " litt le pot ato tub er s" of so me Indi an pot ato cultivars . Seed Research 30: 2 15-222 .

Paul, V. and Eze kie l R. (2003) Gr owth and yiel d per form ance of potato cultivars raised from little tubers. Indian J. Plant Physiol. 8: 181- 185.

Railton , J.D . and Warein g, P.F. ( 1973) . Effe cts of day len gth on endogenous gibberellin in leaves of Solanum andigena. Physiol. Plant. 28: 88-94.

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Schreven, D.A. van (1956) . On the physiology of tuber formation in potatoes . I. Premature tuber formation . Plant Soil 8: 49-55.

Tyagi , B.R., Mishra P.C. and Chauhan, H.S. (1981) . Physio logic al disorders leading to tuber formation inside the mother tuber in potato under prolonged storage. J. Indian Potato Assoc. 8: 151­154.

van Berkel , Solami, 1.F. and Gebhart , C. (1994) . Transcripts

accumulating during cold storage of potato (Solanum tuberosum L.) tubers are sequence related to stress responsive genes. Plant Physiol . 104: 445-452.

Varies, H. de (1878) . Beitrage zur specie lien physiologie and wirtschftlicher kulturpflazen IV. Keimungsgesxhixhte der Kar toffe1knollen (Opera e periodisis) Collata 3: 206-246. Landwirtsch, Jahrb . 7: 217-249.

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