Monday theme 1 1415 1430 large briefing room getahun

1. Genetic Diversity of Potato for Nitrogen Use
Efficiency and Related traits
Baye .B. Getahun
Amhara Agricultural Research Institute, Ethiopia

2. Introduction
 N is one of the most yield limiting nutrients in crop production
globally
 It has played a remarkable role for the crop yield increase
 During green revolution 50% of the crop yield increase was
associated with fertilizer use, especially N (Fischer et al.,
2009)
 Since 1960, the consumption of N has continued with
increasing rate
 In 2011=105.3 million tonnes
 in 2015=112.9 million tonnes(FAO,2011)

3. However,
 Currently, we have two critical problems in N fertilizer
use:
 Increased cost of crop production
 Damage due to nitrate leaching

4.  This price increase affect
developing countries, especially
sub-Saharan African
 Fertilizer use per ha in sub-
Saharan African countries is
low due high price and poor
market
 Sub Saharan African countries
apply 7 kg of fertilizer /ha
(FAO, 2012)
 this suboptimal use of
fertilizer leads to low yield
Trends of fertilizer price 1960-2008

5. Problems of N
 Damage due to nitrate leaching
 Ecosystem saturation &
 water pollution
this is a problem related to developed countries (i.e. over
dose use)
However,
 crop yield is not improved proportionally

6.  Over 40 years, the N fertilizers applied increased by 7.4
fold, whereas
yield increase was only 2.4 fold (Tilman et al 2002)
 Since 1980, global cereal crop yields showed only 1%
growth/year (FAO , 2009)
This indicates that, there is a high reduction in NUE
 Of the applied N globally only 47% is used by the crops
(Lassaletta e al., 2014)

7.  Clearly we face challenges in increasing yield and
efficient use of fertilizer N
 To achieve further yield increment
 To alleviate the environmental pollution
 We need to select for crop varieties with higher NUE
 Potato is one of the crops
 Contribute for env’t pollution (developed countries)
 Suffer from N deficiency (developing countries)

8.  Genetic variation is the basis for crop improvement
 Genetic variation for efficient use of nutrients has been
identified for various crop species (Marschner 1995).
 Potato is one of the major crops that loss nitrate
excessively which leads to nitrate contamination of
ground water.
Because
 The crop has shallow root system
 Poor in penetrating compacted soil &
 Poor in nutrient use efficiency

9.  Potato has diverse gene pool that can be used as a
source traits for various breeding programs
 Genetic variation for NUE of potato has been reported
in wild accessions and commercial cultivars
 We defined NUE as dry tuber weight
per unit of N supplied (Bock 1984)

10. The objective of our study was
 Is there genetic variation in commercial potato cultivars
for NUE under Ethiopian conditions?
 What traits are important for NUE in potato?

11. Location map of the study area

12.  Injibara
 2600 masl
 Average rain fall 2300mm/year
 Average night Temp 80C
 Average day Temp 220C
 Soil = acrisol
(highly leached and acidic)
 Debre-Tabor
 2650 masl
 Average rain fall 1500mm/ year
 Average night temp 11.8 0C
 Average day temp = 230C
 Soil = Luvisol

13.  Planting materials
 A total of 97
 88 Dutch
 9 Ethiopian cultivars were used (CIP based)
 Source and application of fertilizers
 DAP and TSP- P
 Urea – N
 Fertilizer application
 P = 69kg/ha P2O5)... (at planting)
 N= 40 kg and 120 kg/ha (half at emergence and half at
flowering)

14.  The experiment was conducted under rain fed condition
 Design :
 RCBD with 2 rep in split plot
 Main plots: N rates ( Low & high)
 Sub-plots: Genotypes
 Planting
 June 7 /2013 (Injibara)
 June 21/2013 (DebreTabor)
 Spacing:
 (75cm x30cm).
 Each plot consists of about 10 plants

15. Injibara after a month (2013)

16. Debre-Tabor after a month (2013)

17. Measured traits
 Measured more than 25 physiological and agronomic traits
 canopy cover parameters
 Yield and related traits
 Quality traits (TDM% & SG)
 Statistical analysis
 Genstat 16th edition
 SAS version 9.3

18. Result
 Source of variations
 N-level
 Environment
 Genotype

19. Effect of Location and N level on canopy development
Debre-Tabor Injibara
0
20
40
60
80
0 10 20 30 40
Low N High N
Soil cover (%)
BTT
0
20
40
60
80
0 10 20 30 40
Low N High N
Soil cover (%)
BTT
Both location and N level effect were Significant at P≤0.01

20. Effect of location and N level on the tuber yield
Debre-Tabor Injibara
0
200
400
600
800
1000
1200
Low N High N
Tuber yield per plant(g)
0
200
400
600
800
1000
1200
Low N High N
Tuber yield per plant(g)
Location effect was significant at P≤0.01

21. Effect of location and N level on NUE
Debre-Tabor Injibara
0
20
40
60
80
100
120
Low N High N
NUE
0
20
40
60
80
100
120
Low N High N
NUE
N level effect is significant at P≤0.01

22. Effect of maturity group on the total area under the canopy
curve at high N
Debre-Tabor Injibara
0.00
1000.00
2000.00
3000.00
Early Mid late
Total area under the canopy curve
(AUC)
0.00
1000.00
2000.00
3000.00
Early Mid Late
Total area under the canopy curve
(AUC)

23. Effect of maturity group on tuber yield per plant at high N
Debre-Tabor Injibara
0.00
200.00
400.00
600.00
800.00
1000.00
1200.00
Early Mid Late
Tuber yield per plant(g)
0.00
200.00
400.00
600.00
800.00
1000.00
1200.00
Early Mid Late
Tuber yield per plant (g)
In Injibara, the higher photosynthetic capacity of late cultivars is not
translated in to higher tuber yield

24.  Is maturity be the main factor for the variation
between the Ethiopian and Dutch cultivars?

25. Ethiopian and Dutch cultivars in the late maturity group
under high N in Injibara
Total Area under the canopy curve (AUC) Tuber yield per plant(g)
0
200
400
600
800
Ethiopian Dutch
0
500
1000
1500
2000
2500
3000
Ethiopian Dutch
In Injibara, the higher photosynthetic capacity of the Ethiopian cultivars in
particular is not translated in to higher tuber yield

26. Genotypic Variation
 So far we have seen the Total phenotypic variation of
cultivars
 How much of the phenotypic variation is due genetic effect
or due to environment?
 PV = GV + EV

27. Estimates Variance components at LN and HN
Traits Treatm PV GV EV h2 GA%
Tuber No
per plant
Low N 4.13 3.42 0.71 0.8 54.60
High N 8.30 6.81 1.41 0.8 64.75
NUE Low N 274.9 220.3 54.6 0.8 73.25
High N 93.39 67.39 26.0 0.7 94.29
Debre-Tabor

28. Estimates Variance components at LN and HN
Traits Treatm PV GV EV h2 GA%
Tuber No per
plant Low N 1.50 1.23 0.27 0.82 47.87
High N 4.00 3.2 0.8 0.80 47.36
NUE Low N
95.30 38.2 57.1 0.4 25.64
High N 24.91 9.8 15.11 0.4 26.26
traits which have high heritability with high GA% across location , are more
heritable and they have better response for selection
Injibara

29. Association of traits with NUE
Traits
Correlation
coefficient with NUE
Low N High N
Average tuber weight 0.12 0.08
Area under the canopy curve 0.6 0.83
Days to maturity 0.47 0.75
Tuber No per plant 0.38 0.58
Tuber dry matter in percent 0.39 0.44

30.  Conclusion
 There is considerable genetic variation among our cultivars for
NUE under LN and HN condition
 This variation can be exploited for NUE improvement program
 Based on the correlation estimate with NUE, traits like:
 tuber number ,
 total area under the canopy
 days to maturity and
 tuber dry matter in percent(TDM%) showed strong positive
correlation

31. Acknowledgments
• Dr. Gerard van der Linden
• Prof.Richard Visser
• Dr. Maurice Schehr (HZPC)
• Mr. Molla Mekonen
• Potato Research Team ofAdet Agri. Research Center

32. • Thank you