1. EFFECT OF QUALITY OF FARM SAVED COWPEA SEED ON BACTERIAL BLIGHT AND GRAIN YIELD
Njonjo Mary W., Muthomi J, Mwang’ombe A,
Department of Plant Science and Crop Protection
University of Nairobi

2. Introduction
Seed is the most important input since the subsequent practices after planting depend on the quality of seed planted.
Cowpea farmers use seed from the informal seed system which are of unknown quality.
Cowpea is grown in the arid and semi arid areas by farmers who are resource constrained hence prefer use of uncertified seeds which are readily available at planting time.
Some farmers have preference for landraces with attributes which are highly regarded hence the reuse over years.
The seeds are often contaminated with impurities and diseases causing pathogens.

3. Continuation……
The contaminants result in reduced establishment in the field, high incidences of seedborne diseases and subsequently low yields.
The seeds are also often recycled over several seasons which has also been reported to loss of seed quality hence poor yields.
Therefore there is a need to determine the effect of farm saved cowpea seed quality on bacterial blight of cowpea incidence and severity and grain yield.

4. Materials and methods
Effect of farm saved cowpea seed quality on bacterial blight of cowpea and grain yield was determined using farm saved, market sourced and certified seeds of three varieties.
The plots were laid out in a randomized complete block design using split plot layout.
Seedling emergence and rotten seeds were determined at 14 days after planting.
Plant stand was assessed at 2nd, 4th and 6th week after planting.
Bacterial blight of cowpea incidence and severity was assessed on the 2nd and 4th week after planting.
Data collected on yield was dry grain yield, seeds/pod, pods/plant, 1000 seed weight, pod length and dry matter yield.

5. Results
Seedling emergence in farm saved seed reduced by 16.7% compared to certified and market sourced seeds which were not significantly different.
The seedling emergence of farm saved seed was also influenced by environment since it was lower in LM4 by up to 14%.
Fig 1: Effect of quality of cowpea seed on seedling emergence in two sites

6. Effect of farm saved cowpea seed quality on rotten seed
Rotten seedling was highest in farm saved seed by more than 14% compared to certified seed.
It was significantly different across the three seed sources.
Fig 2: Effect of quality of cowpea seed on rotten seed in two sites

7. Effect of farm saved cowpea seed quality on plant stand
Table 1: Plant stand as influenced by seed quality in two site
Effect of farm saved cowpea seed quality on plant stand
Plant stand of farm saved seed reduced by up to 18.2% between the 2nd and 6th week after planting compared to both certified and market seed.
However the results were not consistent between the locations.
Seed Source
LM4
LM5
2nd Week
Market sourced
96.6a
110.2a
Certified
98.8a
107.1a
Farm saved
61.1b
91.7a
Mean
85.0
103.0
LSD(p< 0.05)
23.1
20.6
CV (%)
27.2
20.2
4th Week
6th Week
106.4a
105.8a
87.6a
99.9
LSD
23.3
23.5

8. Effect of farm saved seed quality on bacterial blight of cowpea incidence and severity
Incidence of bacterial blight of cowpea in market seeds increased with up to 11.4% between the 4th and 6th week after planting.
The severity was not affected by the seed sources however it was higher in LM4 than LM5 by over a 100%.
Table 2: Bacterial blight of cowpea incidence and severity as influenced by seed quality in two sites
Seed Source
LM4
LM5
2nd Week
Incidence
Severity
Certified
30.6a
0.9a
22.7a
0.5a
Farm saved
31.8a
1.0a
18.7a
Market sourced
19.2b
0.8a
11.4b
0.4a
Mean
27.2
0.9
17.6
0.4
LSD(p< 0.05)
11.1
0.2
5.8
0.1
CV (%)
41.3
22.8
33.3
32.2
4th Week
1.7a
25.5a
0.7b
19.6ab
0.8ab
1.6a
17.6b
1.7
20.6
0.8
6.7
7.5
33.1
18.6

9. Table 3: Dry grain yield and other components as influenced by seed quality in two site
Seed source
Pods/plant
Seeds/pod
Pod length
1000 seed wgt
Dry grain
Dry matter
LM 4
Farm saved
6.9a
7.9a
11.8a
129.7a
262.0a
1722.0b
Certified
5.7a
7.6a
116.3a
285.0a
2443.0a
Market sourced
4.6a
8.0a
12.0a
134.2a
289.0a
1831.0b
Mean
5.7
7.8
11.8
126.7
279.0
1999.0
LSD(P≤0.05)
2.3
1.6
1.1
16.8
62.0
480.3
CV (%)
40.5
20.8
9.1
13.4
22.5
24.3
LM 5
17.4a
16.6a
126.8b
1474.0ab
6367.0a
14.3ab
12.5a
16.8a
130.5b
1743.0a
6704.0a
11.8b
12.7a
16.9a
135.6a
1343.0b
5719.0a
14.5
12.4
131.0
1520.0
6263.3
6.5
3.4
0.7
4.5
274.9
2061.7
26.2
15.9
8.9
3.5
18.3
33.2

10. Effect of seed source on grain yield and other yield components
In general the mean of all the yield and yield components assessed were higher in LM5 than LM4.
Mean grain yield and dry matter yield of farm saved seed reduced by up to 29.8% and 41.9% respectively compared to certified seeds.
Seeds per pod, pod length and a 1000 seed weight was not affected by the seed source.

11. Discussion and Conclusion
Quality of farm saved seed negatively affected establishment of the cowpea evidenced by the reduced seedling emergence, increase of rotten seeds and reduced plant stand.
The grain yield and dry matter yield was negatively influenced by the quality the farm saved seeds.
It is therefore advisable for farmers to use certified cowpea seed to achieve optimum seedling emergence and plant stand, low incidence of bacterial blight of cowpea and high dry grain and matter yield.

12. THANK YOU