Evaluation of Irrigation Methods, Potato Cultivars and Vermicompost for Integrated Management of the Meloidogyne incognita and Ralstonia solanacearum Disease Complex

Tasew Getu1*, Wassu Mohammed2, Awol Seid3, Tesfamariam Mekete4 and Bekele Kassa5

1Department of Biology, Dire Dawa University, PO. Box 13 62 Dire Dawa, Ethiopia; 2School of Plant Sciences, College of Agriculture and Environmental Sciences, Haramaya University, PO. Box, 138 Dire Dawa, Ethiopia; 3Department of Plant Sciences, Wollo University, PO. Box 1145 Dessie, Ethiopia; 4United States Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine, National Identification Service, 4700 River Road, Riverdale, MD, 20737, Maryland, US; 5Ethiopian Institute of Agricultural Research, Holetta Agricultural Research Center, Ethiopia. PO. Box 2003 Addis Ababa, Ethiopia.

Received | March 05, 2023; Accepted | May 08, 2023; Published | May 22, 2023

*Correspondence | Tasew Getu, Department of Biology, Dire Dawa University, PO. Box 13 62 Dire Dawa, Ethiopia; Email: tasewpatho@gmail.com

Citation | Getu, T., Mohammed, W., Seid, A., Mekete, T. and Kassa, B., 2023. Evaluation of irrigation methods, potato cultivars and vermicompost for integrated management of the Meloidogyne incognita and Ralstonia solanacearum disease complex. Pakistan Journal of Nematology, 41(1): 31-44.

DOI | https://dx.doi.org/10.17582/journal.pjn/2023/41.1.31.44

Keywords | Drip irrigation, Interaction, Management, Marketable tuber yield, Resistant

Copyright: 2023 by the authors. Licensee ResearchersLinks Ltd, England, UK.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Introduction

Potato has been widely described as global food and nutritional security option particularly for the poor people (Singh and Rana, 2013). Potato’s nutritional value is higher than most of the food crops. It is considered as the richest source of carbohydrates (Ali et al., 2015). In addition, the high cash rewards encouraged farmers to be involved in potato production (Elraiah et al., 2014). In Ethiopia, potato is one of the cash crops that plays a significant role in improving farmers’ income and food security (Haverkort et al., 2012; Devaux et al., 2020). Potato production, however, is constrained by diseases and pests, lack of appropriate cultivars with grower desired traits, and soil infertility (Edgar et al., 2010).

The root-knot nematodes (RKN; Meloidogyne spp.) are members of the genus Meloidogyne Goldi (1892), Meloidogyne is of Greek origin and means apple-shaped female (Moens et al., 2009). They are sedentary endoparasites that are highly polyphagous, globally distributed pests that can cause up to 100% yield losses particularly on vegetable crop production (Onkendi et al., 2014; Seid et al., 2015). In Ethiopia, the occurrence of RKN has been reported on a small number of horticultural crops (Abegaz et al., 2019; Kassie, 2019; Mandefro and Mekete, 2002; Miheret et al., 2019; Seid et al., 2019; Tefera and Hulluka, 2000). Seid et al. (2019) reported the occurrence of the four major RKN species, Meloidogyne incognita, M. javanica, M. arenaria, and M. hapla on tomato, using DNA and protein-based identification techniques. Of the RKN species studied to date, M. incognita is the most significant pathogen and is widely distributed in tomato cultivation areas in Ethiopia (Seid et al., 2019). However, there is limited research on its management in this region.

Ralstonia solanacearum (bacterial wilt) is among the most destructive potato diseases globally (EPPO, 2020). Yield losses of 30 to 100% due to R. solanacearum were reported in Kenya and Uganda (Kinyua et al., 2005). In Ethiopia, R. solanacearum has been detected on potatoin many parts of the country including Kefa, Gamugofa, Sidamo, Shashemane, Holetta, Welega, Welo, Shewa, Arsi, Haramaya, Kersa, Gojam, and Tigray (Abdurahman et al., 2017; Gebremedhin et al., 2006; Henok et al., 2007; Kassa 1996; Lemessa and Zeller 2007; Tessema et al., 2020).

The synergistic interaction between RKN and R. solanacearum on various hosts is widely recognized (Ateka et al., 2001; Martin and Nydegger, 1982; Pavithra et al., 2014; Sundaresh et al., 2017). Crop losses are reported to be more aggravated when RKN is present in association with R. solanacearum (Bekhiet et al., 2010; Shahbaz et al., 2015; Sundaresh et al., 2017). In Ethiopia, research information on the management of disease complexes on crops, including potato, is limited.

Management methods using agrochemicals have not been found to be economical in Ethiopian cropping systems and also show toxic effects on a plant, soil, and ground water (Jatala and Martin, 1977; Karimi et al., 2017). Thus, for RKN and R. solanacearum management, it is critical to explore environ mentally friendly alternative approaches. Irrigation is the process of applying water to the soil, primarily to meet the water needs of growing plants. There are three main irrigation methods. Drip irrigation is a method in which water is applied drop by drop directly to the soil overlying the roots. Sprinkler irrigation is similar to natural rainfall where water is pumped through a pipe system and then sprayed onto the crops through rotating sprinkler heads (Shock, 2013). The sub-irrigation/ furrow method is where the water table is raised to or held near the plant root zone using ditches or subsurface drains to supply the water (Bjorneberg, 2013). Drip irrigation has been reported to reduce the transmission of pathogens, reduces water use (80–95%), nitrate leaching, and erosion, increasing marketable yield while sprinkler and furrow irrigated fields are subject to greening or sunscaldand are more susceptible to early and late blight pathogens (Dasberg, 1999; Demmel et al., 2014; Nir, 1982; Shock et al., 2005). Yet, there is limited research done on the effects of irrigation methods on the management of RKN and R. solanacearum disease complex.

Vermicomposting is the digestion of organic materials by earthworms that produce casts. The casts are reported to improve soil fertility and productivity of crops with no pollution of the environment (Gabour, 2015; Yadav and Argaw, 2016) and increase beneficial soil microorganisms (Alemu et al., 2014; Chaoui et al., 2003; Guerrero, 2010; Talashilkar et al., 1999). It also reported to stimulate and diversify microbial biomass and to suppress soil-borne plant pathogens (Yadav, 2011) through induction of systemic acquired resistance in plants, direct toxicity of degradation products, and an increase of natural nematode-antagonist micro-organisms on the compost substrate (Oka, 2010; Zhang et al., 2011). The vermicompost prepared with farm wastes and animal manures were also reported to be rich in nutrients (Atiyeh et al., 2002; Arancon et al., 2006; Yadav et al., 2015).

In Ethiopia, limited research has been conducted which has examined the effects of vermicompost on growth, quality, and yield of vegetablecrops such as garlic (Alemu et al., 2014; Kenea and Gedamu, 2019) and potato (Yadav et al., 2015). However, no research work has been performed on the effect of vermicompost for management of RKN and R. solanacearum, and on the performance of potato cultivars. Therefore, the present research aiming to determine the effect of drip, sprinkle, and furrow irrigation methods alone and in combination with vermicompost for managing Meloidogyne incognita (MI) and R. Solanacearum (RS) disease complex are required. Thus, the objective of the study was to evaluate the effect of irrigation methods, cultivars, vermicompost on development of M. incognita and R. solanacearum diseases complex.

Materials and Methods

Description of the study site

The experiment was conducted at the ‘Raare’ Research Station of Haramaya University (HU), at an altitude of 2022 m.a.s.l. HU is located at 9º41’’N latitude and 42º03’’E longitude. The soil type of the station is silt loam.The area has a bimodal rainfall distribution with a mean annual rainfall value of 760 mm (Tekalign, 2011).

Experimental materials

A total of 13 potato cultivars recommended for cultivation for different agroecologies of the country introduced from 1998 to 2013 were evaluated. The cultivars were tested and shown to be free from viral, wilt and other plant diseases and were obtained from the Amhara Region Agricultural Research Institute (ARARI). The potato cultivars used are shown in Table 1.

Treatments and experimental design

Irrigation methods (drip, furrow and sprinkler), vermicompost and cultivars were evaluated for their effect on MI and RS, separately and in combination. The total number of treatment combinations was 39 (i.e. the 3 irrigation methods × 13 cultivars × vermicompost) and were laid out in a split-split plot designwith three replications. The irrigation methods were considered as a main plot, cultivars as a sub-plot while the vermicompost was considered as a sub-sub plot.

Plot size measured 4.5 m × 3.6 m consisting of six rows that could accommodate twelve rows of plants at space 0.75 m between ridges and 0.30 m between plants, with spacing between plots and adjacent replication of 1 m and 1.5 m, respectively were prepared for planting of the potato cultivars through drip, sprinkler and furrow irrigation methods, separately during the dry season of 2019-2020. Medium size tubers weighing approximately 39 g were planted at a

 

Table 1: List of the tested potato cultivars with code, year of release, breeder, and recommended altitude for production.

Cultivar	Accession code	Year of release	Breeder/ maintainer	Recommended altitude range for production a.s.l
Chirro	AL-111	1998	Haramaya University	1700 - 2400
Gudenie	CIP-386423.13	2006	Hawassa ARC/EIAR	1600 - 2800
Mara Charre	CIP-389701.3	2005	Hawassa ARC	1700 - 2700
Jalenie	CIP-37792.5	2002	Hawassa ARC/EIAR	1600 - 2800
Guassa	CIP-384321.9	2002	Adet ARC	2000 - 2800
Gera	KP-90134.2	2003	DebreBirhan ARC	2700 - 3200
Araarsaa	KP-90138.12	2006	Sinana ARC	2400 - 3350
Belete	CIP-393371.58	2009	Holeta ARC	1600 - 2800
Bedassa	AL-114	2001	Haramaya University	1700 - 2400
Bubu	CIP-384321-3	2011	Haramaya University	1700 - 2000
Dagim	CIP-396004.337	2013	Adet ARC	1700 - 2700
Shonkolla	KP- 90134.5	2005	Hawassa ARC/EIAR	1700 - 2700
Zengena	CIP-380479.6	2001	Adet ARC	2000 - 2800

 

Source: MoANR (2017). ARC/EIAR = Agricultural research center/ Ethiopian institute of agricultural research.a.s.l = above sea level.

 

depth of 5 to 10 cm. Each plot was watered based on Soil Water Tension methods at the 20 cm depth using a Tensiometer. Accordingly, 30-50 centibars (cb) for drip, 50 - 60 cb for sprinkler, and 60 - 80 cb for furrow irrigation were applied (Shock et al., 2006).

Vermicompost preparation and administration

The substrates used for vermicompost preparation were wheat straw, Parthenium hysterophorus, and cow dung collected from the HU farm field. The wheat straw and Parthenium hysterophorus were cut into 3 cm pieces and mixed with cow dung in a 1:1:1 ratio . The mixed substrates were left in cement tanks (vermibed) measuring 2m × 1m × 1m. Moisture was maintained at 60% by sprinkling water (Edwards, 1983). One hundred composting earthworm species Eisenia foetida, commonly known as redworm, were introduced into the tank. The vermibed was covered with wire mesh, to protect the worms from predators. Harvesting was done on the 60th day (Krishnamoorthy and Vajranabhaiah, 1986; Yadav and Argaw, 2016), and the worms were separated from the vermicast. The casts were shade dried, passed through a 2 mm sieve (Pisa and Wuta, 2013), and applied in the soilat the rate of 4 t/ha during planting and before flowering (Arancon et al., 2002).

Nematode extraction and identification

A soil sample measuring 1000 g was collected from each micro-plot before planting the cultivars. Soil and organic samples were also collected after 90 days of planting. The soil samples were collected using a sterile auger up to 25 cm soil depth. The organic samples of about 1000 g were collected using sterile scissors from the mother plants. The collected samples were bagged separately in polyethylene bags and labelled. The soil sample was sieved (2 mm mesh) to remove debris and gravel. After homogenization, sub-samples (100 g) were measured out for extraction. Nematodes were extracted using the Oostenbrink dish technique (Oostenbrink, 1960) then killed (at 65 ºC) with hot TAF (7 ml formalin, 2 ml triethanolamine, and 91 ml distilled water) and mounted in fixative. From each micro-plot, about 25 specimens were examined under compound light microscopy.

Meloidogyne incognita was identified from other Meloidogyne spp. morphologically (head region) based on procedures developed by (Eisenback and Hirschmann, 1981). Soil samples collected from each micro-plot were also tested for the presence of Meloidogyne incognita with a bioassay test using susceptible ‘Moneymaker’ tomato as an indicator plant. The tomato was grown in the collected soil samples in 500 cm3 pots under greenhouse conditions. After eight-weeks, 5 g roots were collected from each pot, washed, and female nematodes stained with 1 ml acid fuchsin (3.5 g acid fuchsin/ 250 ml acetic acid and 750 ml distilled water) and then dislodged with a needle. The posterior portion of the female was cut with a knife and the body contents removed. The cleaned posterior portion of the female was trimmed and transferred to a drop of glycerine on a clean glass microscopic slide then subjected to observation under a stereomicroscope. Meloidogyne incognita was identified based on the perennial pattern described by Taylor and Sasser (1978). The results were also checked with Meloidogyne spp identified previously using molecular techniques.

Ralstonia solanacearum isolation and identification

A soil sample measuring 100 g was collected at a depth of up to 25 cm using a sterile auger from each micro-plot before planting the cultivars. The serial dilution method was applied for bacterial isolation. One gram of soil sub-sample was added to 9 ml of sterile distilled water. The soil suspension was shaken in a rotary shaker until homogenized and suspensions (1×10-4CFU/ml) were poured in a Petridish containing TriphenylTetrazolium Chloride (TTC) solid media (Winstead and Kelman, 1952). The Petridishes were incubated at 28ºC for 48 h. Bacterial colonies showing the irregular mucoid of RS were recorded and streaked on fresh TTC solid media for further purification. At 90 days after planting, RS present in the soil and organic materials were also isolated and identified to allow estimation of bacterial reproduction. RS isolateswere identified based on morphological, physiological, and biochemical tests (Goszczynska et al., 2000).

Data collection

Final nematode population (Pf) was calculated by summation of eggsand soil population, reproduction factor (Rf) was calculated by dividing Pf by the initial nematode population (Pi). The number of galls per root systemand tuber (G/R), egg masses per root system and tuber (EM/R), root and tuber gall index (RGI), egg mass index (EMI) were recorded before planting (for Pi), and after ninety days of planting for the other parameters.The number of egg masses per root system and tuber were counted after staining with phloxine ‘B’ (0.15 g/l water) according to Hooper et al. (2005). Root and tuber gall or egg mass indiceswere determined as described by Taylor and Sasser (1978). Resistance/susceptibility of the cultivars to the nematode was scored using ratings depicted by Pederson and Windham (1989). RGI = [∑ (Si × Ni) ÷ (N × 5)] ×100; where Si is root and tuber galling scale of 0, 1, 2, 3, 4, 5,where 0 = no galls; 1 = 1 or 2, 2 = 3 –10; 3 = 11 –30; 4 = 31 – 100 and 5 > 100. Ni is the number of plants in each root and tuber galling scale. N is the total number of evaluated plants. Immune RGI = 0; highly resistant 0.1 ≤ RGI ≤ 5.0; resistant 5.1 ≤ RGI ≤ 25.0; moderately susceptible 25.1 ≤ RGI ≤ 50.0; susceptible 50.1 ≤ RGI ≤ 75.0; highly susceptible RGI > 75.0. Roots and tubers were rated for galling severity on 0 to 4 scale, where 0 = no galling (0%), 1 = light galling (1% – 25%), 2 = moderate galling (26% – 50%), 3 = heavy galling (51% – 75%), 4 = severe galling (76% – 100% galled root and tuber) according to Barker (1985).

The initial R. solanacearum colony number (RSI) was recorded before planting, while final RS colony number (RSF) was calculated by summation of RS in the soil and tuber after ninety days of planting. Appearance of symptoms and wilted foliage were also recorded. Resistance/susceptibility of the cultivars to bacterial wilt was scored using indices described by Winstead and Kelman (1952). Bacterial wilt index (BWI) = ∑ (ni × vi) ÷ (V × N); where the ni=number of plants with the respective disease rating; vi = disease rating: 0 = no wilting, 1 = < 10% wilted plants, 2 = 11% – 25% wilted plants, 3 = 26% – 50% wilted plants, 4 = 51% – 75% wilted plants, 5 = > 75% wilted plants; V = the highest disease rating (5); and N=the number of plants observed. Highly resistant (BWI = 0.0 – 0.2), resistant (BWI = 0.21–0.3), moderately resistant (BWI = 0.31 – 0.4), moderately susceptible (BWI=0.41–0.5), susceptible (BWI = 0.51 – 0.60), highly susceptible (BWI = 0.61 – 0.9), extremely susceptible (BWI = 0.91 – 1.0). Marketable yield (MY), unmarketable yield (UMY), total tuber yield (TTY; MY plus UMY) in t/hawere recorded ninety days after planting.

Data analysis

All the M. incognita, R. solanacearum, plant related data, and their interactions were analyzed by one-way ANOVA following the procedures suggested by Gomez and Gomez (1984). The mean of the data werecompared using Duncan Multiple Range Test (DMRT) at P ≤ 0.05. All analyses were computed using SAS software version 9.2 (SAS, 2009).

Results and Discussion

The development of Meloidogyne incognita on potato cultivars

The parameters of Meloidogyne incognita (MI): final nematode population (Pf), reproduction factor (Rf), number of galls per root systemand tuber (G/R), rootand tuber gall index (RGI), egg masses per root system and tuber (EM/R) and egg mass index (EMI) were highly significantly (P ≤ 5%) influenced by methods of irrigation, cultivars, vermicompost (VC), and their interactions (Supplementary Table 1).

Most of the tested cultivars showed different mean values of Pf with all tested irrigation methods.‘Gudenie’, ‘Belete’ and ‘Bubu’ cultivars had the lowest Pf with drip irrigation amended with VC followed by sprinkler and furrow irrigation amended with VC whereas ‘Jalenie’ had the highest Pf with all applied irrigation methods. ‘Shonkolla’ also recorded the highest Pf with sprinkler and furrow irrigation methods in the soil which was not amended with VC.‘Gudenie’had the lowestmean values (2.2) of Rf with drip irrigation amended with VC whereas ‘Mara Charre’ had the highest mean values (8.6) of the parameter with sprinkler irrigation in the soil which was not amended with VC (Table 2).

None of the potato cultivars planted with different irrigation methods was free from MI infection. The cultivar ‘Belete’ registered the lowest mean values of G/R (6.6) and RGI (2.0) with drip irrigation amended with VC, respectively while ‘Jalenie’ registered the highest mean values of G/R (48.6) and RGI (4.0) with furrow irrigation alone, respectively. This cultivar also registered the second-highest value of the parameter with drip and sprinkler irrigation methodswithout VC. Egg masses were formed on all of the cultivars tested and with all applied treatments. The cultivar ‘Belete’ generated the lowest mean values of EM/R (7.0) and EMI (2.0) with drip irrigation in soil amended with VC, respectively while ‘Jalenie’ produced the highest values of EM/R with most treatments (Table 3).

All thecultivars planted under the differenttreatment schemes showed various galling scales and resistance categories to MI. The roots and tubers of all tested

 

Table 2: Final nematode population and reproduction factor as influenced by irrigation methods, cultivars, and vermicopost.

Cultivar

Irrigation methods

Final nematode population

Reproduction factor

D+VC

F+VC

S+VC

D

F

S

D+VC

F+VC

S+VC

D

F

S

Chirro

41.6bc

58bc

48c

67bc

82bc

70bc

3.4bc

6.1abc

3.9bcd

5.4abcd

7.8a

5.3bcd

Gudenie

26.6d

39.6f

31.6e

44e

56d

49.3e

2.2c

3.6cd

2.3d

3.1d

5.0c

4.3cd

Mara Charre

36c

56.3cd

44.3cd

61d

74.6c

65.6cd

2.9bc

6.3ab

3.1cd

7.9a

6.4abc

8.6a

Jalenie

50.6a

70.3a

59.3a

74.6a

93a

82a

4.8ab

5.9abc

5.1b

5bcd

7.9a

6bcd

Guassa

40bc

55.3cde

46cd

60.3d

78c

66.6cd

3.5abc

6.6a

3.4bcd

5.9abc

6.4abc

5.0cd

Gera

39.3bc

57.3cd

47c

62cd

77.3c

71.6b

3.7abc

6.1abc

3.3bcd

6abc

5.9abc

6.4bc

Araarsaa

39.6bc

53cde

48c

62cd

78.3c

70bc

5.7a

6.2abc

9.1a

5.9abc

5.3bc

4.8cd

Belete

24.6d

36.6f

29.3e

42.3e

54d

46e

2.4c

3.8bcd

2.8cd

3.6cd

5.8abc

3.8d

Bedassa

35.6c

51.3de

44.6cd

58d

73.3c

64.6d

3.2bc

5.4abc

3.8bcd

6.7ab

6.3abc

6.3bcd

Bubu

23.6d

37f

28.3e

41.6e

57d

47e

2.4c

2.8d

2.5d

3.4cd

6.0abc

4.5cd

Dagim

37c

49.6e

42.6d

58.3d

74c

63.6d

2.9bc

4.4abcd

4.1bcd

6.1abc

6.8abc

4.5cd

Shonkolla

44.6ab

63.3b

55.3b

69.6ab

89.6a

78.6a

4.0abc

5.1abcd

4.5bc

6.4ab

7.5ab

7.5b

Zengena

38bc

53.6cde

46cd

60.6d

74.3c

65cd

2.6bc

4.7abcd

3.9bcd

4.7bcd

5.0c

6.1bcd

 

Mean values sharing common letter(s) within columns of each parameter did not differ significantly at P ≤ 0.05 according to Duncan Multiple Range Test (DMRT). D+VC = drip irrigation amended with VC, F+VC= furrow irrigation amended with VC, S+VC = sprinkler irrigation amended with VC, D = drip, F = furrow S= sprinkler irrigation, VC= vermicompost.

 

Table 3: Number of galls and egg mass per root system and tuber on potato cultivars as influenced by irrigation methods, cultivars, and vermicopost.

Cultivar

Irrigation methods

Number of galls per root system and tuber

Egg mass per root system and tuber

D+ VC

F+ VC

S+ VC

D

F

S

D+ VC

F+VC

S+VC

D

F

S

Chirro

19.6 ab

31 ab

24.6 ab

34.3ab

45ab

38.3abc

17.6 ab

27abc

21abc

32.6a

40.3ab

33.6ab

Gudenie

9.0 ef

16.6 f

11.3 de

19.3ef

26.3d

22.6f

8.6 ef

14.6fg

10e

16.3ef

23de

19d

Mara Charre

11.3 def

22 e

15.6 cd

25.3de

35c

29.3e

10 def

20de

12.6de

22.6de

30.6c

24.6c

Jalenie

23.3 a

34.6 a

27.6 a

38.0a

48.6a

42a

20.6 a

31.6a

25.3a

33.3ab

43a

38.6a

Guassa

17.3 abcd

27.3 bcd

21.3 abc

29.6 bcd

38.3 bc

34.3 bcde

15 abcd

24.6 bcde

18.3 bcd

26.6 abcd

34bc

30.3bc

Gera

15 bcde

28.3 bc

21b c

29.6bcd

39.3bc

36.3abcd

13.3 bcde

25bcd

18bcd

25.6bcd

34.6bc

32.3b

Araarsaa

23.3 a

29.3 bc

25.3 ab

33.3abc

41.6abc

37abcd

19.6 a

25.6bc

22ab

29.6abcd

37abc

33.6ab

Belete

6.6 f

14.3 f

9.0 e

17.3f

24.3d

20.6f

7.0 f

12.6g

8.3e

15.3f

22e

18.3d

Bedassa

15 bcde

25.2 cde

19.6 bc

28bcd

36.6c

32.3de

12.6 cdef

22.3cde

17.6bcd

25cd

33.3bc

29.3bc

Bubu

8.3e

14.0f

10 ef

16.6f

24.3d

21.3f

8.6ef

12.6g

8.3e

14.6f

21.6e

18.6d

Dagim

18.3 abc

25.6 cde

21bc

29.3bcd

36.3c

32.6cde

16 abc

22.3cde

18.3bcd

25.6bcd

32c

29.3bc

Shonkolla

20.6 ab

32 ab

25.3 ab

34.6ab

45.3ab

38.6ab

18 ab

29ab

22.3ab

30.3abc

40.6ab

35.3ab

Zengena

12.3 cdef

22.6 de

18c

26cde

34c

29.3e

11.6 cdef

19.3ef

15.6cd

23.3cd

29.6cd

25.6c

 

Mean values sharing common letter(s) within columns of each parameter did not differ significantly at P ≤ 0.05according to Duncan Multiple Range Test (DMRT). D+VC = drip irrigation amended with VC, F+VC = furrow irrigation amended with VC, S+VC = sprinkler irrigation amended with VC, D = drip, F = furrow, S = sprinkler irrigation, VC = vermicompost.

 

cultivars showed light galling (LG) with drip irrigation amended with VC. ‘Belete’ and ‘Bubu’ generated LG with all tested treatments whilst ‘Jalenie’, ‘Araarsaa’ and ‘Shonkolla’ in all tested treatments produced moderate galling (MG) except with drip irrigation amended with VC which showed LG.

All cultivars that were grown with drip irrigation amended with VC fell under the‘resistant’ (R) category to MI. ‘Gudenie’, ‘Belete’ and ‘Bubu’ with all tested treatments identified as ‘R’ while ‘Jalenie’, ‘Araarsaa’ and ‘Shonkolla’ with all tested treatment grouped under ‘moderately susceptible (MS) except with drip irrigation amended with VC which exhibited ‘R’ (Table 4).

Development of Ralstonia solanacearum on potato cultivars

Ralstonia solanacearum related parameters: RS final colonies (RSF) and bacterial wilt index (BWI) were significantly influenced (P ≤ 0.05) by methods of irrigation, cultivars, VC, and their interactions (Supplementary Table 2).

The lowest mean values of the RSF and BWI were registered for plants with drip irrigation amended with VC. However, plants with furrow, sprinkler, and drip irrigation methods without VC recorded the first, second and third, respectively highest values of the bacterial parameters. ‘Belete’ recorded the lowest mean values (2.6) of RSF with drip irrigation amended with VC while ‘Jalenie’ and ‘Shonkolla’ recorded the highest values (8.6) and (8.5), respectively of the RSF with furrow irrigation alone. The mean values of initial RS colonies on which treatments were applied were found to be 2.9 × 105 (detailed data not presented). ‘Gudenie’, ‘Belete’, ‘Dagim’ and ‘Bubu’ registered the lowestmean values of BWI with the drip irrigation amended with VC. Among the tested cultivars, ‘Jalenie’ registered the highest BWI with all tested treatments (Table 5).

 

Table 4: Nematode resistance category on potato cultivars as influenced by irrigation methods and potato cultivars in soil amended with and without vermicompost.

	Resistance category
	Irrigation methods
Cultivar	D+VC	F+VC	S+VC	D	F	S
Chirro	R	MS	R	MS	MS	MS
Gudenie	R	R	R	R	MS	R
Mara Charre	R	R	R	MS	MS	MS
Jalenie	R	MS	MS	MS	MS	MS
Guassa	R	MS	R	MS	MS	MS
Gera	R	MS	R	MS	MS	MS
Araarsaa	R	MS	MS	MS	MS	MS
Belete	R	R	R	R	R	R
Bedassa	R	MS	R	MS	MS	MS
Bubu	R	R	R	R	R	R
Dagim	R	MS	R	MS	MS	MS
Shonkolla	R	MS	MS	MS	MS	MS
Zengena	R	R	R	MS	MS	MS

 

R=Resistant, MS= moderately susceptible. D+VC = drip irrigation amended with VC, F+VC = furrow irrigation amended with VC, S+VC = sprinkler irrigation amended with VC, D = drip, F = furrow, S = sprinkler irrigation, VC = vermicompost.

 

Table 5: Final Ralstonia solanacearum colonies (× 105) and bacterial wilt index as influenced by irrigation methods, cultivars, and vermicopost.

Cultivar

Irrigation methods

Ralstonia solanacearum final colonies

Bacterial wilt index

D+ VC

F+ VC

S+VC

D

F

S

D+VC

F+VC

S+VC

D

F

S

Chirro

4.4 abc

6.3ab

5.3a

7.3a

8.3abc

7.5ab

0.17bc

0.44bc

0.28b

0.48b

0.76b

0.58bc

Gudenie

3.2 ef

4.2ef

3.3c

4.4ef

5.8efg

5.1d

0.03e

0.11f

0.04g

0.30f

0.36c

0.33ef

Mara Charre

3.4 cdef

4.6 cde

3.9bc

5.5cde

6.4def

5.6cd

0.06de

0.29cde

0.14def

0.28cd

0.66b

0.33ef

Jalenie

4.4 abc

6.7a

5.4a

7.1ab

8.6a

7.8a

0.30a

0.75a

0.37a

0.70a

1.0f

0.84a

Guassa

3.7 bcde

5.6 abcd

3.7bc

5.9bcd

7.3bcd

6.6abc

0.09cde

0.32bcd

0.18cde

0.29cd

0.71b

0.48cde

Gera

3.6 bcde

5.7 abc

4.6ab

5.9bcd

7.6abcd

7.0ab

0.11cde

0.35bcd

0.23bcd

0.32c

0.73b

0.55bcd

Araarsaa

4.8a

5.8 abc

5.3a

6.7abc

8.0abc

7.4ab

0.23ab

0.46b

0.30ab

0.47b

0.84ab

0.70ab

Belete

2.6f

3.4f

2.9c

3.8f

5.3fg

4.6d

0.04e

0.14ef

0.05g

0.12ef

0.29c

0.40f

Bedassa

3.4 cdef

5.2 bcde

4.6ab

5.9bcd

7.3bcd

6.6abc

0.10cde

0.31bcd

0.23bcd

0.31c

0.71b

0.45cde

Bubu

2.9ef

3.4f

3.0c

3.9f

5.1g

4.5d

0.04e

0.11f

0.06fg

0.22def

0.35c

0.32f

Dagim

4.2 abcd

5.3 bcd

4.5ab

5.9bcd

7.0cde

6.4bc

0.04e

0.27de

0.11efg

0.31cde

0.63b

0.34def

Shonkolla

4.6ab

6.4 ab

5.3a

6.7abc

8.5a

7.4ab

0.15bcd

0.36bcd

0.24bc

0.34bc

0.83ab

0.58bc

Zengena

3.0ef

4.5 def

3.7bc

5.1de

6.4def

5.7cd

0.07cde

0.29cde

0.22bcd

0.32c

0.60b

0.35def

 

Mean values sharing common letter(s) within columns and rows of each parameter did not differ significantly at P ≤ 0.05according to Duncan Multiple Range Test (DMRT). D+VC = drip irrigation amended with VC, F+VC = furrow irrigation amended with VC, S+VC = sprinkler irrigation amended with VC, D = drip, F = furrow, S = sprinkler irrigation, VC = vermicompost.

 

All cultivars except ‘Jalenie’ and ‘Araarsaa’were identified as ‘highly resistant’ to RS with the drip irrigation amended with VC. The cultivars were also identified as ‘highly susceptible’with furrow irrigation alone except ‘Gudenie’, ‘Belete’ and ‘Bubu’ which ranked as ‘moderately susceptible’ under the same treatment (Table 6).

The effect of irrigation methods, cultivars and vermicompost on yield of potato

All potato yield related parameters including marketable yield (MY), unmarketable yield (UMY) and total tuber yield (TTY) were highly significantly (P ≤ 0.05) influenced by methods of irrigation, cultivars, and their interactions (Supplementary Table 3).

Guassa and Bubu had the highest mean values (47) and (47.9), respectively of MY with drip irrigation amended with VC. However,‘Bedassa’ and ‘Dagim’ produced the lowest values (9.9) and (9.7), respectively of the parameterwith furrow irrigation without VC. ‘MaraCharre’ and ‘Zengena’ produced the highest mean values (18.1) and (17.5), respectively of UMY with drip irrigation amended with VCwhereas ‘Bedassa’ and ‘Dagim’ registered the lowest mean value (6.3) of the parameter with furrow irrigation alone.All the tested potato cultivars registered significantly different total tuber yield (MY plus UMY). ‘Gudenie’, ‘Guassa’, ‘Belete’ and ‘Bubu’ had the highest mean values (58.6), (59.6), (57.6) and (59.8), respectively of TTY with drip irrigation amended with VC nevertheless ‘Gera’, ‘Bedassa’ and ‘Dagim’ produced the lowest values (17.4), (15.4) and (15.1), respectively of the parameter with furrow irrigation without VC (Table 7).

 

Table 6: Bacterial wilt resistant category of potato cultivars as influenced by irrigation methods, cultivars, and vermicopost.

Cultivar	Bacterial wilt resistant category
	Irrigation methods
	D+VC	F+VC	S+VC	D	F	S
Chirro	HR	R	R	MS	HS	S
Gudenie	HR	HR	HR	R	MR	MR
Mara Charre	HR	R	HR	R	HS	MR
Jalenie	R	MS	MR	HS	HS	HS
Guassa	HR	MR	HR	R	HS	MS
Gera	HR	MR	R	MR	HS	S
Araarsaa	R	MS	R	MS	HS	HS
Belete	HR	HR	HR	HR	MR	R
Bedassa	HR	MR	R	MR	HS	MS
Bubu	HR	HR	HR	R	MR	MR
Dagim	HR	R	HR	MR	HS	MR
Shonkolla	HR	MR	R	MR	HS	S
Zengena	HR	R	R	MR	S	MR

 

D+VC = drip irrigation amended with VC, F+VC = furrow irrigation amended with VC, S+VC = sprinkler irrigation amended with VC, HR/S = highly resistant/susceptible, MS/R = moderately susceptible/resistant, R = resistant, S = susceptible.

 

Table 7: The marketable and unmarketable yield of potato cultivars as influenced by irrigation methods, cultivars, and vermicopost.

Cultivars

Irrigation methods

Marketable yield (t/ha)

Unmarketable yield (t/ha)

D+VC

F+VC

S+VC

D

F

S

D+VC

F+VC

S+VC

D

F

S

Chirro

39.8abcd

33.1d

35bc

28.2c

20.8c

26.3c

12.4bc

7.0de

6.3f

6.6cde

8.1bc

5.3g

Gudenie

44.6ab

38b

41.3a

32.8b

27ab

30.5b

13.7b

13.4a

12.1ab

11.7ab

12.3ab

10b

Mara Charre

36.2bcd

27.8f

30.7cd

23.5d

16.6d

21.3e

18.1a

7.6cde

7.3e

7.1cde

7.6bc

5.8f

Jalenie

34.5cd

32.6d

35.7bc

27.9c

21c

25.7c

14.5b

8.9bcd

8.5d

8.4cd

7.7bc

7e

Guassa

47a

41.6a

41.9a

36.3a

28a

33.5a

16.9ab

11.6ab

11.4b

12.7a

9.8abc

9.3c

Gera

30.6d

16.6k

18.9e

13.3h

10.5f

11.6i

12.1bc

7.2de

7.4e

6de

7.7bc

5.2g

Araarsaa

38.3abcd

20.4h

22.8e

16.5f

11.7f

15.2g

14.4b

8.8bcd

8.4d

8.2cde

7.9bc

6.8e

Belete

44.2abc

28.9e

31.8cd

24.4d

17.3d

22.3d

13.8ab

10.3bc

10.2c

9.6bc

9.6abc

8.1d

Bedassa

38.3abcd

18.7i

21e

14.9fg

9.9f

13.7h

12.7b

5.6e

5.1g

5.2e

6.3c

4.1h

Bubu

47.9a

37c

40.2ab

31.8b

23.6bc

29.7b

16.2ab

13.2a

12.8a

12.5a

13.2a

10.7a

Dagim

32.2d

18.4i

20.6e

14.6gh

9.7f

13.4h

10.7d

5.5e

5g

5.1e

6.3c

4h

Shonkolla

36.9bcd

26.3g

29d

21.9e

16de

20.2f

15ab

8.8bcd

8.4d

8.2cde

7.5bc

6.8e

Zengena

33.6d

17.7j

19.9e

14.3gh

12.5ef

13h

17.5a

8.4cd

7.3e

7.2cde

7.7bc

5.9f

 

Mean values sharing common letter(s) within columns of each parameter did not differ significantly at P ≤ 0.05 according to duncan multiple range test (DMRT). D+VC = drip irrigation amended with VC, F+VC = furrow irrigation amended with VC, S+VC = sprinkler irrigation amended with VC, D = drip, F = furrow, S = sprinkler irrigation, VC = vermicompost.

 

The development of M. incognita and infection of R. solanacearum were significantly influenced by methods of irrigation regardless of potato cultivars and vermicompost. In addition, the irrigation methods, the potato cultivars, and the use of VC affected both MI and RS. Plants grown with drip irrigation in soil amended with VC demonstrated the lowest mean values of G/R, EM/R, Pf, RSF and BWI compared with plants grown with sprinkler and furrow irrigation methods. Thus, use of the drip irrigation method, particularly in soil supplemented with VC may offer great potential for managing the MI and RS disease complex. Our data are in agreement with previous studies (Dasberg, 1999; Nir, 1982; Shock et al., 2005) which reported that drip irrigation reduces the transmission of pathogens while sprinkler and furrow irrigated soilis more suited for the dissemination of the pathogens. In terms of application of VC, the results presented here are consistent with those of earlier studies (Awad-Allah and Khalil, 2019; Akhtar and Malik, 2000; Edwards et al., 2007; Mohamed et al., 2019; Olabiyi and Oladeji, 2014; Pathma and Sakthivel, 2012; Yadav, 2011). These studies, conducted on different crops, reported VC application, suppressed nematode population increase, root and tuber galling and egg mass number found in the soil.

None of the potato cultivarswas found to be fully resistant to MI under any of the applied methods of irrigation. However, the potato cultivars reaction to MI were different. ‘Gudenie’, ‘Belete’ and ‘Bubu’ were recorded as ‘resistant’ under all tested treatments while ‘Jalenie’, ‘Araarsaa’ and ‘Shonkolla’ grouped under the ‘moderately susceptible’ category to MI except when grown by drip irrigation in combination with VC amended soil which allowed suppression of nematode reproduction to a level that allowed them to be considered ‘resistant’. This implies that the presence of VC suppresses the development of MI. VC suppresses soil-borne plant pathogens through induction of systemic acquired resistance in plants, direct toxicity of degradation products and an increase of natural nematode-antagonist micro-organisms on the compost substrate (Oka, 2010; Zhang et al., 2011). Genetic differences between the different potato cultivars meant that they responded differentlyto the tested irrigation methods in terms of their response to nematodes. Considerable differences among potato cultivars to nematode infection have been recorded, ranging from highly susceptible tohighly resistant to nematodes. The resistant cultivars are infected by fewer developed nematodes than relatively susceptible cultivars (Bekhiet et al., 2010; Dropkin and Nelson, 1960; Hussain et al., 2016; Montasser et al., 2019). All the potato cultivars that were grown underdrip irrigation in soil amended wth VC fall under the ‘resistant’ and ‘highly resistant’ category to MI and RS, respectively. This showed that when plants are grown with drip irrigation with VC has a significant role in controlling both nematodes and bacterial disease complex growth and reproduction.

The highest values for MY, and TTY were recorded with drip irrigation in soil amended with VCcompared to un-amended soil. This may show the irrigation method and the presence of VC contribute incrementally to the plant yield parameters. Previous researchers (Dasberg, 1999; Nir, 1982; Shock et al., 2005) also reported that drip irrigation increases the marketable yield of crops more than sprinkler and furrow irrigated soil. A significant increase in plant growth parameters of pakchoi and garlic grown on soil supplemented with VC were reported (Kenea and Gedamu, 2019; Ramnarain and Abdullah, 2018). This might be due to the ability of VC to supply nutrients in a readily accessible form and also increases nutrient uptake by the crop which inturn enhances plant growth. VC may also suppress plant pathogens, thus enhancing plant health and minimizing yield losses (Oka, 2010; Pathma and Sakthivel, 2012; Zhang et al., 2011). Mohamed et al. (2019) also reported that the application of VC increased the quality of fruits, and increasesthe marketable yield of olive oil fruits through suppression of soil-borne plant pathogens.

Conclusions and Recommendations

From the present study, it can be concluded that M. incognita and R. solanacearum are influenced by irrigation methods, cultivars, vermicompost, and their interactions. The application of drip irrigation particularly in soil amended with vermicompost had a major impact on the M. incognita and R. solanacearum disease complex. These treatments positively affected tuber yield. More efforts are required to integrate disease management for sustainable control of such soil-borne disease complexes and to improve crop yield.

Acknowledgments

This work is part of a Ph.D. dissertation of the first author. The authors are thankful to the Ministry of Science and Higher Education (MoSHE) and Haramaya University (HU) for their extended material, technical and financial support in carrying out this study.

Novelty Statement

This research is novel. No one has conducted it before.

Author’s Contribution

All authors contributed to this part of a Ph.D. dissertation of the first author. Material preparation, data collection and analysis were performed by Tasew Getu. The first draft of the manuscript was written by Tasew Getu and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Funding

The research was funded by Ministry of Science and Higher Education, and Haramaya University, Ethiopia.

Availability of data and material

Raw data were generated at Haramaya University. Derived data supporting the findings of this study are available from the corresponding author [Tasew Getu] on demand.

Code availability

Not applicable.

Supplementary Material

There is supplementary material associated with this article. Access the material online at: https://dx.doi.org/10.17582/journal.pjn/2023/41.1.31.44

Conflict of interest

The authors have declared no conflict of interest.

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