Performance of Promising Potato Clones for Growth and Yield Characters in Bhaktapur, Nepal

INTRODUCTION

Potato, popularly known as king of vegetables, is one of the most important crops of Nepal. It is grown in all agro- ecological zones of 77 districts ranging from 100 to 4400 masl

 

(Dhital & Khatri, 2004). People residing in terai and mid hills consume potato as a major vegetable while in high hills it is used as a staple food. It is the fourth most important crop after rice, wheat and maize; however holds first position in productivity. Its annual production is 2,805,582 tons with the productivity of 14.03 mt/ha (MoAD, 2017). It is highly nutritious food constituting good source of energy, vitamins and minerals. Potato cultivation is a major source of income for small holder farmers in mid and high hills. It plays vital role in maintaining the food security and eliminating the poverty and malnutrition in Nepal. Despite its huge importance and cultivation potentiality, its production is very low as compare to the neighboring countries. Many factors are responsible for low yield of potato but lack of high yielding and late blight resistant varieties is the bottleneck constraint for potato cultivation in Nepal.

The production of existing cultivated varieties is not enough to meet increasing market demand. Farmers are forced to recycle the same low yielding variety for years. Variety development is a continuous process to replace old degenerating varieties with new improved varieties. National Potato Research Programme (NPRP) is responsible to conduct series of on-station and on-farm trials for developing new variety. On-farm trials are important to speed up the variety development process and enhance the adoption of new varieties in farm communities (Romney et al., 2003; Assefa et al., 2005). Besides, it enables the incorporation of farmers’ opinions and ensures testing of varieties under farmers’ management. Therefore as a part of on-farm trials, the experiment was conducted to evaluate growth and yield performance of promising potato clones in Bhaktapur and hence improve the productivity of potato through selection of appropriate potato clones in Bhaktapur. These clones were tested in various trials of several stations of the country but in Bhaktapur they were introduced for the first time in the present study.

MATERIALS AND METHODS

Five promising potato clones PRP 35861.18, CIP 384866.5, PRP 226267.11, CIP388676.1, and PRP 85861.11 were  brought from NPRP, Khumaltar, Lalitpur and planted in farmers' field along with Desiree as check variety in winter-spring season of 2018. The experiment was laid out in Randomized Complete Block Design with 4 replications in Bhaktapur (1348 masl). The ridge of 3m long was prepared using potato ridge maker at a spacing of 60 cm. Well sprouted potato tuber seed of 25-30 g containing at least 2 eyes were planted at 25cm apart. The individual plot size was 7.2 m² with four ridges containing 12 plants each. The plot was fertilized at the rate of 100:100:60kg N:P₂O5:K₂O and 20mt FYM per hactare. The cultural practices and observation techniques were performed as per the recommendation of  NPRP (Khatri et al., 1999). Observations were recorded on growth and yield characters. Plant Uniformity was recorded using 1to 5 scale [1 = Very poor (completely heterogeneous in plant size and vigour), 2 = Poor (Some heterogeneous in plant size and plant vigour), 3 = Fair (average or acceptable), 4 = Good (relatively high homogeneity in plant size, plant vigour and growth) and 5 = Excellent (completely homogeneous in plant size, plant vigour and growth) (Khatri et al., 1999)]. Plant vigour was also recorded using 1 to 5 scale [1 = very weak (all the plants are small, <20 cm), few leaves, weak plants, very thin stems and light   green color, 2 = 75% the plants are small (<20 cm) or all the plants are between 20 and 30 cm, the plants have few leaves, thin stem and light green color, 3 = medium, intermediate or normal, 4 = vigorous, 75% of the plants are over 50 cm, robust with foliage of dark green color, thick stems and leaves very well developed, and 5 = very vigorous, all the plants are over 70 cm and ground coverage is complete. The plant are robust, with thick stems and abundant foliage of dark green color. (Khatri et al., 1999)].

Data entry, management and descriptive analysis was done using MS Excel 2007. ANOVA and DMRT were done using R 3.5.1 and R-Studio 1.1.453.0 version (R core team, 2017) and significance level was defined at 5%.

RESULTS

Growth characters

The results of germination, plant uniformity and vigour are presented in Table 1. Significant variation in germination among the clones was observed at 30 DAP. Desiree showed the higher germination as compared to the promising potato clones of CIP. PRP clones showed similar germination to 'Desiree' indicating competitiveness of new clones to  an established early variety. The germination of clones was found statistically non significant at 45 DAP. PRP 85861.11 and PRP 35861.18 were similar but superior to Desiree for plant uniformity at 60 DAE while the variation was non significant at 30 DAE. PRP 35861.18 had higher plant vigor at both 45 DAE and 60 DAE than CIP 388676.1.

Table 1. Germination, uniformity and plant vigor of potato clones in Bhaktapur, 2018

 

Treatment

Germination (%)

 

Uniformity

 

Plant Vigor

 

 

30DAP

45DAP

45 DAE

60DAE

45DAE

60DAE

PRP 35861.18

63.46±12.49^a

98.75±2.5

4.5±0.58

4.5±0.58^ab

3.75±0.96^a

4.25±0.5^a

CIP 384866.5

30.21±19.65^b

92.71±7.12

3.25±0.5

3.5±0.58^c

2.75±0.5^bc

3.75±0.5^ab

PRP 226267.11

54.17±36.49^ab

93.75±7.98

4.00±0.82

4±0.82^abc

3.25±0.5^ab

4.25±0.5^a

CIP 388676.1

34.38±27.72^b

90.63±7.12

3.75±0.96

3.75±0.96^bc

2.25±0.5^c

3.0±0.00^c

PRP 85861.11

55.13±18.12^ab

92.29±3.56

4.25±0.96

5±0.0^a

3.25±0.5^ab

3.50±0.58^bc

Desiree

73.75±17.46^a

97.92±4.17

3.5±0.56

3.25±0.5^c

3±0.0^abc

3.00±0.00^c

F test

**

NS

NS

*

*

**

P value

0.00002

0.10719

0.25

0.00179

0.0175

0.00163

CV%

30.26

4.65

19.76

16.46

16.89

11.9

LSD

23.65

6.614

1.15

0.99

0.77

0.65

Significance codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Note: DAP=Days after Planting, DAE= Days after emergence, LSD=Least Significant Difference, CV%=Coefficient of Variation Percentage

 

The results of stem thickness, plant height and ground cover of the potato clones are presented in Table 2. The highest stem thickness was shown with PRP 226267.11. Plant height also varied significantly among the clones. At 45 DAE PRP 35861.18 was the tallest while at 60 DAE PRP 35861.18 and PRP 226267.11 were the tallest among the tested clones. Desiree was the most dwarf clone in both observations. Statistically significant variation was observed in ground cover of clones. PRP 226267.11 and PRP 85861.11 were recorded as superior to Desiree for ground cover.

Table 2. Effect of clones on stem thickness, plant height and ground cover in Bhaktapur, 2018

 

Stem thickness(cm)

Plant height (cm)

Ground cover at 60 DAE

Treatment

45 DAE

60 DAE

45DAE

60DAE

PRP

35861.18

3.01±0.22^b

3.16±0.06^bc

50.95±6.47^a

62.45±4.1^a

75±8.16^ab

CIP

384866.5

3.36±0.53^ab

3.31±0.2^ab

37.80±6.62^c

51.16±6.11^b

75±4.08^ab

PRP

226267.11

3.69±0.53^a

3.54±0.35^a

44.70±6.76^b

61.50±11.6^a

80±4.08^a

CIP

388676.1

3.12±0.07^b

2.9±0.26^c

30.75±3.87^d

39.70±5.24^c

48.75±4.79^c

PRP

85861.11

3.27±0.46^b

3.08±0.22^bc

42.90±6.10^b

49.20±3.67^b

77.50±6.45^a

Desiree

3.24±0.26^b

3.0±0.23^bc

33.63±5.46^d

40.88±4.52^c

67.5±6.45^b

P value

0.0281

0.00762

2.84e-07

1.47e-06

3.95e-05

F- test

*

**

***

***

***

LSD

0.38

0.32

4.15

6.10

9.39

CV%

7.65

6.67

6.86

7.97

8.82

Significance codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Note: DAE= Days after emergence, LSD=Least Significant Difference, CV%=Coefficient of Variation Percentage

Among the 6 tested clones, the growth pattern of  PRP 35861.18 was found as lodging, CIP 388676.1 as erect and the remaining 4 clones as spreading type. CIP 388676.1 was categorized as late maturity type (>135), Desiree as early type (<115) and remaining 4 clones as medium maturity type (115-135). All 5 promising potato clones were seen resistant against late blight while Desiree was highly susceptible.

 

Table 3. Variation in growth characters among potato clones in Bhaktapur, 2018

 

 

Treatment

Growth Habit

Maturity

Late Blight

PRP 35861.18

Lodging

Medium

Mild Resistant

CIP 384866.5

Spreading

Medium

Resistant

PRP 226267.11

Spreading

Medium

Resistant

CIP 388676.1

Erect

Late

Highly Resistant

PRP 85861.11

Spreading

Medium

Highly Resistant

Desiree

Spreading

Early

Highly Susceptible

 

Yield characters

The tuber distribution by weight and number as well as yield of the tested clones is illustrated in Table 4. Significantly higher USN and USW per plant was reported with PRP 85861.11 among the tested clones. SSN and SSW per plant also varied significantly among the clones. PRP 85861.11 produced the highest SSN while PRP 85861.11 and PRP 35861.18 gave the highest SSW per plant. Similarly the significant highest OSN and OSW per plant was observed with CIP 388676.1

Table 4. Effect of clones on yield parameters of potato in Bhaktapur, 2018

 

Treatments

USN /

plant

USW /

plant

SSN /

plant

SSW /

Plant

OSN/

Plant

OSW /

plant

Yield

(mt/ha)

PRP

35861.18

3.9

±1.16^b

53.85

±13.37^b

4.95

±0.74^ab

173.25

±28.94^a

1.35

±0.41^b

88.65

±29.44^b

21.05

±3.20^ab

CIP

384866.5

6.75

±2.75^b

84.25

±36.60^ab

4.25

±1.05^bc

137.25

±36.34^ab

0.90

±0.68^b

65

±53.26^b

19.1

±3.35^b

PRP

226267.11

5.95

±2.09^b

72.00

±17.76^b

4.95

±1.41^ab

168

±36.34^a

1.60

±0.82^b

125.75

±89.33^b

24.38

±5.49^a

CIP

388676.1

5.1

±3.93^b

69.1

±52.51^b

3.05

±1.15^c

101.1

±33.43^b

2.55

±1.0^a

196.3

±93.53^a

24.43

±2.51^a

PRP

85861.11

10.85

±0.66^a

118.95

±17.60^a

6.2

±0.75^a

174.7

±16.93^a

0.95

±0.9^b

73.90

±52.81^b

24.5

±4.59^a

Desiree

4.75

±1.23^b

51.25

±11.70^b

3.95

±0.19^bc

133.35±

16.55^ab

1.35

±0.7^b

94

±48.71^b

18.57

±4.34^b

F test

**

*

**

*

**

**

*

P value

0.0024

0.0455

0.00447

0.0181

0.00713

0.00847

0.02239

CV%

31.61

38.27

20.03

20.01

37.67

41.39

13.20

LSD

2.96

43.20

1.336

43.30

0.81

66.92

4.39

Significance codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Note: USN=Undersize (<25gm) number, SSN=Seed size (25-50gm) number, OSN= Oversize (>50gm) number, USW= Undersize (<25gm) weight, SSW=Seed size (25-50gm) weight, OSW=Over size (>50gm) weight, LSD=Least Significant Difference, CV%=Coefficient of Variation Percentage

 

The variation in tuber yield of clones was found statistically significant. PRP 85861.11 (24.5mt/ha), CIP 388676.1(24.43mt/ha) and PRP 226267.11(24.38mt/ha) were found statistically similar and superior for tuber yield. Desiree (18.57 mt/ha) produced the least yield among the tested clones.

Among the six tested clones, three were oval shaped, two were oblong shaped and one was round in shape. The tubers of 2 clones were with shallow eye, 2 with medium and 2 with deep eyes. Regarding the tuber color, 2 clones were white colored, 3 with red color and one with yellow color. Similarly, variation was noticed in tuber flesh color as mentioned in Table 5.

Table 5. Variation in tuber characteristic among potato clones in Bhaktapur, 2018

 

Treatment

Shape

Eye depth

Tuber color

Tuber Flesh color

PRP 35861.18

Oval

Medium

White

White

CIP 384866.5

Round

Deep

Yellow

Pale yellow

PRP 226267.11

Oval

Medium

Red

Cream

CIP 388676.1

Oval

Shallow

White

White

PRP 85861.11

Oblong

Deep

Red

Cream

Desiree

Oblong

Shallow

Red

Yellow

 

Based on the external appearance of tuber and the total production, PRP 226267.11 held the first position by farmer’s ranking. Organoleptic taste ranking of boiled potato reported PRP 85861.11 as the most delicious clone among all (Table 6)

 

 

Table 6. Farmers’ ranking and organoleptic taste ranking

 

Treatment

Farmer’s ranking

Organoleptic taste ranking of

boiled potato

PRP 35861.18

3

5

CIP 384866.5

5

2

PRP 226267.11

1

3

CIP 388676.1

2

6

PRP 85861.11

4

1

Desiree

6

4

 

DISCUSSION

The potato clones tested at CFFT, RARS Nepalgunj (NPRP, 2016/17) reported that there is significant variation in germination at 30DAP. The lower germination of promising clones as compared to Desiree might be due to presence of some growth inhibitors in seed tuber and its susceptibility to prolonged frost at early period of planting. Burton and Meigh (1971) also reported that benzothiazole, 1,4-dimethylnaphthalene and 1,6- dimethylnaphthalene are comparatively potent inhibitors of sprout growth in the potato tuber. PRP 35861.18 and CIP 388676.1 had shown the highest and lowest plant vigour respectively in our study which corresponds to the finding of Upadhyay et al. (2017). Ahamad et al. (2012) reported non significant variation in plant uniformity, ground cover and late blight. It might be due to different genotypes, weather and environmental condition.

Upadhyay et al. (2017) reported PRP 35861.18 and CIP 388676.1 as the tallest and shortest clones respectively among the tested clones which agrees with our findings. Significant variation in plant height among the genotypes was observed in Gautam et al. (2004) and Ghimire et al. (2004). Abbas (2011) reviewed and reported that varieties vary in flesh and skin colour, eye depth and tuber shape.

Upadhyay et al. (2017) reported significant variation in number of seed size tuber and over size tuber only but the finding of this study showed significant variation in number of all tubers types. Cho and Iritani (1983) reported that tuber number is function of stem population but is influenced by cultivars and several other factors, which control vegetative growth. Dhakal et al. (2011) and Chapagain et al. (2014) reported that the varieties significantly influenced the yield of tuber per plant. According to Upadhyay et al. (2017) PRP 85861.11 gave the highest yield and Desiree produced the lowest among 6 tested clones which is quite similar to our finding. It might also be due to similar environmental condition of Bhaktapur and Kavre.

CONCLUSION

Hence it can be concluded that all 5 promising potato clones performed better than Desiree with respect to growth and yield parameters. PRP 85861.11, CIP 388676.1 and PRP 226267.11 were the superior clones regarding the tuber yield. All the promising clones were found resistant to late blight while Desiree was found highly susceptible. PRP 35861.18 showed the better growth performance. The farmers’ preference was high for PRP 226267.11 and organoleptic taste ranking boiled potato of tested clones proved PRP 85861.11 as superior one in term of taste and texture. Further research on these promising clones should be carried out so that NPRP can release and recommend the new high yielding variety for farmers.

ACKNOWLEDGEMENT

Authors are grateful to Agriculture and Forestry University (AFU) and Prime Minister Agriculture Modernization Project (PMAMP) for providing space for research in the command area of Potato Zone, Bhaktapur. We appreciate the attempt of National Potato Research Programme, Khumaltar for providing trial set of FFT under the project 'Potato Varietal Development for different Agro-ecologies of Nepal; NARC GRANT No. 506.