Long term effect of soil solarization on soil properties

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Long term effect of soil solarization on soil properties and cauliflower vigor Article in Phytoparasitica · July 2013 DOI: 10.1007/s12600-013-0331-z

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Long term effect of soil solarization on soil properties and cauliflower vigor

T. A. Sofi, A. K. Tewari, V. K. Razdan & V. K. Koul

Phytoparasitica ISSN 0334-2123 Volume 42 Number 1 Phytoparasitica (2014) 42:1-11 DOI 10.1007/s12600-013-0331-z

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Author's personal copy Phytoparasitica (2014) 42:1–11 DOI 10.1007/s12600-013-0331-z

Long term effect of soil solarization on soil properties and cauliflower vigor T. A. Sofi & A. K. Tewari & V. K. Razdan & V. K. Koul

Received: 2 March 2013 / Accepted: 17 July 2013 / Published online: 9 August 2013 # Springer Science+Business Media Dordrecht 2013

Abstract The effect of soil solarization on physical, chemical and biological properties of soil was studied, along with the response of cauliflower seedlings following solarization. Nursery beds were covered with transparent polyethylene sheet and soil temperature and moisture were recorded. Soil samples were collected five times for analysis. Three cauliflower nurseries were raised at 30-day intervals; germination was recorded 10 days after sowing and seedling length 30 days after sowing. The maximum temperature in solarized soil ranged from 40.2–47.2°C, with an increase of 5.2° to 9.9°C over non-solarized soil. There was a conservation of 5.48% moisture in solarized soil as compared with non-solarized. Solarization significantly increased electrical conductivity, organic carbon, nitrogen and potassium over pre-solarized soil. The mean pH, EC, Ca, Mg, N, P, K and C recorded in T. A. Sofi (*) Division of Plant Pathology, SKUAST-Kashmir, Srinagar, Jammu & Kashmir, India e-mail: [email protected] A. K. Tewari Department of Plant Pathology, G.B. Pant University of Agriculture and Technology, Pantnagar, U.S. Nagar, Uttaranchal, India V. K. Razdan Division of Plant Pathology, SKUAST-Jammu, Jammu, Jammu & Kashmir, India V. K. Koul Division of Entomology, SKUAST-Jammu, Jammu, Jammu & Kashmir, India

solarized soil was higher than in non-solarized. Soil solarization reduced the population of fungi from 25.68 x 104 to 4.8 x 104, bacteria from 20.28 x 106 to 5.66 x 106, actinomycetes from 31.60 x 105 to 4.40 x 105, and reduction in population was recorded even after 90 days, when compared with non-solarized soil. Solarization effectively reduced (>97%) population of plant parasitic and free living nematodes. Cauliflower seedlings in solarized soil had a better vigor index than non-solarized soil. Present findings reveal that soil solarization could be exploited for nutrient management and soilborne pests control, with a better vigor index of vegetable nursery. Keywords Temperature . Moisture . Microbial population . Nematodes . Nutrients

Introduction Cauliflower (Brassica oleracea var. botrytis L.) is an important vegetable crop grown in India, with the second position in its production in the world; it has a total acreage of 3,69,000 ha, an annual production of 67,45,000 mt, and the productivity 18.3 mt ha-1 (NHB 2011). However, the productivity is low as compared with Italy, USA and China. Cauliflower grown in subtropical areas of Jammu (India) is considered as the queen of winter vegetables. Poor soil physical condition, nutrient deficiencies, pests, weeds and increased fertilizer demand are explanations for low crop productivity. These fundamental constraints undoubtedly

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limit the effectiveness of other yield-enhancing technologies. Few appropriate technologies are available for resource-poor farmers to address these problems. Soil solarization is one such modification in soil environment that has been tested for the management of soilborne pathogens and to enhance agricultural productivity (Matheron & Porchas 2010; Sofi et al. 2009). Soil solarization improves soil structure and increases the availability of nitrogen (N) and other essential plant nutrients (Elmore et al. 1997), which leads to increased plant growth and reduced fertilizer requirements. A number of soilborne pathogens, viz., Pythium, Phytophthora, Rhizoctonia, Fusarium, Sclerotinia, Sclerotium and phytonematodes like Helicotylenchus, Tylenchorhynchus, Tylenchus, and Hoplolaimus are associated with soilborne diseases. Control of soilborne pathogens is often hampered by the fact that both the inocula of pathogens and lethal agents applied to the soil are affected by the physical, chemical and biological factors of the soil environment. Seed and soil treatment with fungicides is a common practice for the management of soilborne diseases but these have not produced a desired long term solution and are not eco-friendly. Seed treatment with fungicides often fails to achieve effective management because a number of pathogens are associated with soilborne diseases. Many alternative methods for managing the soilborne plant pathogens have been tried, among them soil solarization – advocated to be an inexpensive and non-hazardous method. Soil solarization involves trapping of solar heat through polyethylene covering to raise the soil temperature to the level where it becomes lethal to temperature-sensitive or mesophilic soil microorganisms, the category to which most of the plant pathogenic microorganisms belong. The potential advantage of soil solarization is that it is a non-chemical method which is not hazardous to the user and does not involve substances toxic to the environment, consumer, host plant or beneficial microorganisms. As global concerns regarding environmental quality grow along with the human population, concepts such as solarization and other uses of solar energy in agriculture will likely become increasingly important. The Jammu sub-tropical conditions offer adequate opportunity for the soil and nursery management through soil solarization. The lack of information about soil solarization for the management of physical, chemical and biological properties of soil motivated this investigation

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into the effectiveness of soil solarization on these properties and on the growth of cauliflower seedlings.

Materials and methods Soil solarization In the selected field with a known history of nematode and other pathogen infestation, the soil surface was smoothed and leveled prior to mulching. The thoroughly prepared nursery beds were pre-irrigated to the level of field capacity and raised 15 cm above ground level. Transparent polyethylene sheets 25 μm thick were then laid with the edges anchored firmly by burying in trenches surrounding the treated area. The sheets were laid in complete coverage, in a crust and trough manner (like a wave). Solarization was carried out for a period of 80 days.

Soil sampling The selected location, with hot summers, is located at 32.43°N latitude and 74.54°E longitude at an altitude of 300 m AMSL. The temperature at times rises up to 48.0°C. Rainfall occurs from July to September with an average of 1115.9 mm. Humidity is highest during July to September. In winter (December to February), temperature remains between 13.5° and 25°C, and rainfall is 150 mm. High temperatures (35–45°C) occur during May–June. The inherent physico-chemical properties of the soil are sandy loam in texture with pH 7.3, EC 0.03 dsm-1, organic carbon 0.37%, available nitrogen 195 kg ha-1, phosphorus 15.3 kg ha-1 and potassium 153 kg ha-1. In order to carry out physical, chemical and biological analysis of the soil, samples were collected five times: just before solarization, immediately after solarization (i.e., after removal of polyethylene mulch), and the remaining three samples at subsequent 30-day intervals, viz., 30, 60 and 90 days after solarization. The soil samples were drawn to a depth of 10 cm from each plot with the help of a soil auger. For all samples five cores were collected per replication, bulked to form a composite sample, and brought to the laboratory in polyethylene bags for study. Soil temperature Soil thermometers were placed at a depth of 10 cm beneath the polyethylene sheet to record the soil temperature. Temperature of nonsolarized soil was recorded in the same way. Daily

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maximum soil temperature was recorded and the average standard week’s temperature calculated. Soil moisture Soil samples collected from the experimental plots just before solarization, just after solarization, and the non-solarized control were used for determination of soil moisture. This was done by gravimetric method, wherein the samples were weighed and then dried in an oven at 105°C until constant weight was achieved. The dried samples were weighed and the moisture percentage was calculated by using the following formula: Weight of wet soil−weight of oven dry solid  100 Weight of oven dry soil

Chemical properties of soil Composite soil samples were oven-dried at 105°C for 24 h. Dry soil samples were then sieved (2 mm) and the fine soil was used for chemical analyses (pH, EC, carbon (soluble), NPK, Ca and Mg). Soil acidity (pH) was measured in a 1:2 (w/v) soil-to-water mixture by a pH meter. Electrical conductivity (EC) was determined at 25°C in a 1:1 (w/v) soilto-water mixture by conductivity meter and expressed as dsm-1. Total nitrogen (N) was determined by micro Fig. 1 Standard weekly temperatures of solarized and non-solarized soil (at 10 cm depth)

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Kjeldahl method (Bremner & Mulvaney 1982). Available phosphorus (P) was determined with a spectrophotometer (Olsen & Sommers 1982), available potassium (K) by flame photometry (Knudsen et al. 1982), total organic carbon (%) by potassium dichromate wet digestion method (Schnitzer 1982). Calcium and magnesium were evaluated by ammonium acetate method (Metson 1961). Microbial population Dilution plate method was followed to determine microbial population of fungi, bacteria and actinomycetes in soil. The media used were peptone dextrose rose bengal agar for fungi, soil extract agar for bacteria, and starch ammonium agar for actinomycetes. The soil samples were analyzed to determine the colony forming units (cfu) of the fungi, bacteria and actinomycetes per gram of soil. One gram of the soil was taken from each thoroughly mixed airdried sample and suspended in 9 ml sterile distilled water. Further dilutions were made by transferring 1 ml of suspension to 9 ml of sterilized distilled water until the final dilution of 10-6 was obtained. Dilutions of 104 , 10-5 and 10-6 for fungi, actinomycetes, and bacteria, respectively, were poured into petri plates containing appropriate media and spread evenly by horizontal tilting. The plates were then incubated at 24 ± 2°C, 2

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Table 1 Effect of soil solarization on soil moisture (mean ± SEM) Treatment

Moisture (%)

Pre-solarized soil

13.17 ± 0.45

Solarized soil

12.25 ± 0.35

Non-solarized soil

6.76 ± 0.41

t- value: Pre-solarized vs solarized soil 3.27* Solarized vs non-solarized soil 10.07* * Significant (P=0.05)

days for bacteria and 5 days for fungi and actinomycetes. Microbial colonies were counted with the aid of a colony counter. Nematode population Total nematode population including free-living nematodes and different types of plant parasitic nematodes was determined by Cobb’s sieving and decanting (gravity) method followed by modified Baermann’s funnel method. A soil sample of 250 g was placed in a bucket and 3 l of water was added to it. It was stirred until all clods were broken, then stirring was stopped for 30–60 seconds. The water was then passed through a 20-mesh sieve and subsequently through 100-, 200- and 325-mesh sieves. The residue on the mesh sieves was then washed with a gentle stream of water to remove fine soil particles. The sieves were then inverted and washed into a beaker with 50 ml of water. The washings of different mesh sieves were collected in the beaker and kept still for about 30 min to settle the nematodes at the bottom. Extra water was gently poured out to concentrate the nematodes. The suspension containing nematodes was then further processed by modified Baermann’s funnel method, wherein a coarse mesh with tissue paper overlapping it was placed over the small bowl. The

concentrated suspension of nematodes was poured through tissue paper and kept undisturbed for 48 h under the continuous touch of tissue paper. After 48 h the water in the bowl was collected in the counting dish and examined under stereobinocular microscope to count different types of nematodes. The nematode population was expressed as number per 250 g of soil. Field preparation for nursery After removing the polyethylene sheets from solarized plots, 50-cm2 beds of both solarized and non-solarized were prepared at 50 cm apart from each other, and seeds (2250 per 50 cm2) were sown for nursery raising. The seeds sown in non-solarized soil served as check. Seedling growth In order to evaluate the effect of soil solarization on growth of seedlings, seeds were sown in the beds just after solarization (var. ‘Agheni’), 30 days after solarization (var. ‘Snowball-16’) and 60 days after solarization (var. ‘Snowball-16’). The vigor index was calculated according to the following equation (Orchard 1977): Seedling vigor index (SVI)=(seedling length (cm)× germination percentage) Twenty seedlings were selected randomly from each replication and seedling length was recorded immediately after carefully uprooting the seedlings from the nursery beds. The seedlings were uprooted 30 days after sowing. Germination was recorded by counting the number of seedlings 10 days after sowing (when no further germination occurred) and germination percentage was calculated as follows:

Germination% ¼

Number of seedlings emerged  100 Total number of seeds sown

Table 2 Effect of soil solarization on chemical properties of soil (mean ± SEM) Treatment

pH

EC (dSm-1)

C (%)

N (kg ha-1)

P (kg ha-1)

K (kg ha-1)

Ca (me l-1)

Mg (me l-1)

Pre-solarized soil 7.31 (± 0.10) 0.03 (± 0.00) 0.37 (± 0.03) 195.3 (± 16.4) 15.33 (± 0.87) 153.33 (± 3.33) 11.30 (± 0.15) 0.90 (± 0.05) Post-solarization 7.56 (± 0.03) 0.16 (± 0.01) 0.58 (± 0.01) 362.0 (± 8.50) 21.20 (± 2.51) 202.1 (± 4.04)

11.80 (± 0.26) 2.00 (± 0.55)

Increase over 0.25 pre-solarized soil t- value 2.3ns

0.13

0.21

166.70

5.87

48.77

0.50

1.10

8.51*

7.57*

14.69**

3.54ns

41.20**

1.64ns

2.19ns

ns = Non-significant; * Significant (P=0.05); ** Significant (P=0.01)

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Table 3 Effect of soil solarization on chemical properties of soil at different intervals after solarization Treatment

Chemical properties

Solarized

Non-solarized

Days after solarization

Days after solarization

0

30

60

90

Mean

0

30

60

90

Mean

pH

7.56

7.47

7.48

7.40

7.47

7.30

7.23

7.20

7.16

7.22

EC (dSm-1)

0.16

0.15

0.11

0.10

0.13

0.03

0.03

0.02

0.03

0.02

Ca (me l-1)

11.80

11.55

11.40

10.90

11.41

11.40

11.25

11.00

10.10

10.93

Mg (me l-1)

2.00

1.95

1.60

1.70

1.81

1.10

1.75

1.20

1.25

1.32

-1

N (kg ha )

362.0

356.0

298.0

272.0

322.0

195.0

192.0

189.0

176.0

188.0

P (kg ha-1)

21.20

25.00

26.10

25.30

24.40

18.10

22.00

22.20

23.00

21.32

K (kg ha-1)

202.10

200.50

200.00

197.20

199.95

150.00

143.00

144.50

143.30

144.95

C (%)

0.58

0.57

0.57

0.53

0.56

0.33

0.41

0.48

0.42

0.41

C.D. (P = 0.05)

pH

EC

Ca

Mg

N

P

K

C

Treatment

0.09

0.02

0.25

0.34

7.25

1.79

4.31

0.02

Treatment × days

NS

NS

NS

NS

14.50

NS

NS

0.04

Results and Discussion Soil temperature A significant difference between the temperatures of solarized and non-solarized soils was observed during the course of the investigation. The maximum temperature (weekly mean) ranged from 40.2° to 47.2°C in solarized soil, with an increase of 5.2° to 9.9°C over non-solarized soil (Fig. 1). The absolute (weekly maximum) temperature recorded in solarized and non-solarized soils ranged from 41.0–49.8°C and 34.7–43.5°C, respectively. The absolute temperature increase in solarized soil over non-solarized soil ranged from 5.7° to 10.7°C. These findings are close to those of several workers who have advocated that increased temperatures in solarized soil were due to the trapping of the solar energy by polyethylene sheets and preventing the heat loss caused by evaporation and convection, thus creating a greenhouse effect (Ioannou 1999; Raj et al. 1997). Gelsomino & Cacco (2006) recorded an average soil temperature of 55°C beneath the polyethylene film at 8 cm depth compared with 35°C in non-solarized soil. Table 4 Effect of soil solarization on the population (cfu = colony forming units) of fungi, bacteria and actinomycetes (mean ± SEM)

** Significant (P=0.01)

Treatment

Since in the present study the highest temperature of 49.8°C was recorded in solarized soil at a depth of 10 cm, at lower depths the temperature would have been more than 49.8°C. Microorganisms and plant propagules, present beneath the pre-irrigated polyethylene mulch, start germination and multiplication, which cause warming of the microclimate beneath the polyethylene sheet. During this process a lot of CO2 is released due to respiration of microorganisms and germinating seeds, which accumulate under the mulch. The humidity under the tarp increases due to evaporation of water. The CO2 and water vapors create a greenhouse effect under the mulch. The soil temperature may increase due to these factors as well and rise up to a lethal level (higher than 45°C as compared with the control in the present study) to kill the microorganisms. Soil moisture Covering the soil with a polyethylene sheet resulted in prolific condensation on the inner surface of the sheet. After solarization, loss of moisture was observed both in solarized as well as in non-

Microbial population (cfu / g of soil) Fungi (x 104)

Bacteria (x106)

Actinomycetes (x 105)

Pre-solarized soil

25.68 ( ± 1.22 )

20.78 ( ± 0.79 )

31.60 ( ± 1.31 )

Post-solarization

4.80 ( ± 0.07 )

5.66 ( ± 0.26 )

t- value

17.84**

15.93**

4.40 ( ± 0.31 ) 16.89**

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Table 5 Effect of soil solarization on microbial population (cfu = colony forming units) of fungi, bacteria and actinomycetes at different intervals after solarization Treatment

Microbial population (cfu / g of soil) Fungi (x 104)

Bacteria (x106)

Actinomycetes (x 105)

Days after solarization

Days after solarization

Days after solarization

0

30

60

90

Mean 0

30

60

90

Mean 0

30

60

90

Mean

Solarized soil

4.80 5.20 5.92 6.84 5.69 5.66 7.10 8.86 8.62 7.56 4.40 5.98 8.52 10.44 7.33 (1.75)z (1.82) (1.93) (2.05) (1.89) (1.89) (2.09) (2.28) (2.26) (2.13) (1.67) (1.93) (2.25) (2.43) (2.07)

Non-solarized soil

19.02 (2.99)

21.98 24.98 28.68 23.66 20.16 21.42 22.66 25.72 22.49 26.82 29.42 31.42 31.70 29.84 (3.13) (3.25) (3.39) (3.19) (3.05) (3.10) (3.16) (3.28) (3.15) (3.32) (3.41) (3.47) (3.48) (3.42)

Mean

11.91 (2.37) Fungi

13.59 15.45 17.76 (2.47) (2.59) (2.72)

C. D. (P=0.05)

12.91 14.26 15.76 17.17 (2.47) (2.59) (2.72) (2.77) Bacteria

15.61 17.70 19.97 21.07 (2.50) (2.67) (2.86) (2.96) Actinomycetes

Treatment

0.03

0.05

0.07

Days

0.04

0.07

0.10

Treatment x Days

0.06

0.10

0.14

z

Values in parenthesis are log transformed

solarized soil. The initial soil moisture content of 13.17% (before solarization) was reduced to 12.25% and 6.76% in solarized and non-solarized soil, respectively (Table 1), resulting in the conservation of 5.49% more moisture in solarized soil as compared with nonsolarized soil. A reduction of only 0.92% moisture in solarized soil was observed as compared with the initial (before solarization) moisture content. Conservation of soil moisture by solarization is in agreement with the findings of Stapleton et al. (1987) and Rao & Krishnappa (1995). The prolific condensation on the inner surface of polyethylene sheets during solarization and prevention of loss caused by evaporation, could be

the reasons for enhanced conservation of moisture in solarized as compared with non-solarized soil. Chemical properties of soil There was a significant increase in electrical conductivity (0.13 dSm-1), organic carbon (0.21%), nitrogen (166.70 kg ha-1) and potassium (48.77 kg ha-1) in solarized soil over presolarized soil; however, a non-significant increase in pH (0.25), phosphorus (5.87 kg ha-1), calcium (0.50 me l-1) and magnesium (1.1 me l-1) was observed (Table 2). The mean pH (7.47), EC (0.13 dsm-1) , Ca (11.41 me l-1), Mg (1.81 me l-1), N (322.0 kg ha-1), P (24.4 kg ha-1), K (199.95 kg ha-1) and C (0.56%) observed in solarized

Table 6 Effect of soil solarization on nematode population (mean ± SEM) Treatment

Nematode population (no./ 250 g of soil ) Plant parasitic nematodes

Free-living nematodes Total no. of nematodes

Helicotylenchus Tylenchorhynchus Tylenchus

Hoplolaimus

Pre-solarized soil 1026 ± 106

1130 ± 116

1439 ± 148 619 ± 61

1436 ± 146

5650 ± 578

Post-solarization

31.0 ± 2.0

37.0 ± 3.0

39.0 ± 3.0

152.0 ± 12.0

30.0 ± 2.0

17.7 ± 1.2

Percent reduction 97.07

97.25

97.42

97.14

97.28

97.30

t-value

21.94**

19.20**

23.94**

22.73**

21.24**

20.54**

** Significant (P=0.01)

90

Mean

Mean

Values in parenthesis are log transformed

0.18

0.18

0.13

0.16

0.11

0.16

0.11

0.16

0.12

0.17

0.11

0.12

776.3 (5.50)

1513.3 (7.31)

39.3 (3.69)

Treatment x Days

465.3 (6.11)

558.6 (6.32)

138.5 (4.24)

Days

341.0 (5.62)

558.3 (6.32)

372.3 (5.90)

Total no. of nematodes 0.08

296.8 (4.77)

194.3 (4.62)

541.7 (6.29)

140.3 (4.95)

C. D. (P = Helicotylenchus Tylenchorhynchus Tylenchus Hoplolaimus Free-living 0.05) nematodes Treatment 0.08 0.08 0.09 0.09 0.08

569.7 (6.34)

565.0 (6.33)

Nonsolarized Soil Mean

24.0 (3.20)

17.7 (2.92)

Solarized soil

z

1086.0 974.0 (6.98) (6.87)

247.7 (5.51)

60

574.3 566.0 610.8 (5.18) (5.41) (6.19) Free-living nematodes

1121.0 (7.01)

309.7 (5.73)

58.7 (4.08)

818.0 (6.69)

90

822.8 (6.68)

991.7 (6.89)

654.0 (6.47)

90

0

55.7 (4.02)

30

301.7 (5.71)

60

815.0 (6.69)

90

302.4 (5.01)

Mean

306.4 (5.05)

Mean

152.0 (5.02)

0

228.3 (5.42)

30

90

1022.5 (6.90)

Mean 1238.7 3284.7 1225.9 (7.12) (8.08) (6.41)

60

Days after solarization

692.0 674.0 741.2 (5.42) (5.59) (6.39) Total no. nematodes

1043.1 1346.7 1292.3 1180.7 1230.0 1262.4 (6.94) (7.20) (7.16) (7.07) (7.11) (7.03)

243.85 37.3 (4.79) (3.63)

Mean

Tylenchus Days after solarization

650.2 (5.60)

736.3 (6.39)

1023.1 (6.90)

2883.0 2700.1 3010.7 4117.3 (6.82) (6.98) (7.79) (8.29)

1241.7 1163.0 1228.3 1286.5 5614.0 5172.0 4782.7 4950.0 5129.6 (7.12) (7.05) (7.11) (7.15) (8.62) (8.54) (8.47) (8.50) (8.53)

60

30

Days after solarization 90

783.5 (6.63)

978.8 (6.88)

46.0 (3.84)

30

0

30

60

581.3 (6.15)

941.7 (6.84)

27.7 (3.35)

0

513.1 (5.34)

549.0 (5.19) Hoplolaimus

923.3 (6.82)

234.65 (4.78)

Days after solarization

982.3 (6.88)

1068.0 (6.97)

Nonsolarized Soil Mean

625.3 (6.42)

0

44.0 (3.79)

30.0 (3.42)z 239.3 (5.48)

0

Solarized soil

60

Days after solarization

Days after solarization

30

Tylenchorhynchus

Helicotylenchus

Treatment Microbial population (No./ 250 g of soil)

Table 7 Effect of soil solarization on nematode population at different intervals after solarization

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soil was significantly higher than non-solarized soil. Effect of soil solarization on chemical properties of soil at different time intervals revealed that after solarization no significant difference was observed in pH, EC, Ca, Mg, P and K at 0, 30, 60 and 90 days after solarization (Table 3). EC (0.16 dSm-1), pH (7.56), Ca (11.8 me l-1), Mg (2.0 me l-1), N (362.0 kg ha-1), K (202.1 kg ha-1) and C (0.58%) were recorded at 0 days after solarization and decreased with an increase in days after solarization. However, phosphorus slightly increased up to 60 days after solarization and thereafter decreased. In solarized soil the nitrogen level at 0 and 30 days after solarization was statistically at par and significantly higher than nitrogen at 60 and 90 days after solarization, thus showing a trend to decrease from 30 to 90 days after solarization. The carbon level in solarized soil – (0.58%), (0.57%) and (0.57%) – observed at 0, 30 and 60 days after solarization, respectively, was statistically at par but significantly higher than at 90 days after solarization (0.53%). These results are in conformity with the results of several workers (Chauhan et al. 1988; Lazarovits et al. 1991). Stapleton et al. (1985) found that soil solarization increased concentrations of N, P, Ca, Mg and electrical conductivity. Sharma & Sharma (2002a) reported increased EC, organic Ca, N, K and decreased P after solarization. Overman & Jones (1986) reported an increase in soil pH by soil solarization. Gamliel & Katan (1991) recorded an increase in K+ in solarized soil. Sharma & Sharma (2002b) reported an increased organic carbon in solarized soil. No significant change in pH, EC, Ca, Mg, P and K was observed among different days, i.e., 0, 30, 60 and 90 days after solarization. The pH, EC, Ca, Mg, N, P, K and C observed in solarized soil at 0, 30, 60 and 90 days after solarization was higher than that observed in non-solarized soil, thus showing a long-term effect of soil solarization of at least 90 days. A study in California showed that nitrogen concentration in the top 15 cm soil depth increased 26–177 kg ha-1 (Katan 1987). Solarized soils commonly undergo an increase in soluFig. 2 Effect of soil solarization on germination of cauliflower seeds

Phytoparasitica (2014) 42:1–11

ble substances that can be detected as a rise in the electrical conductivity reported in our study. This change can be attributed to an increase in the rate of decomposition of organic matter at high temperatures and as the mesophilic organisms are killed and degraded during solarization, thereby liberating soluble substances into the soil. Microbial population Soil solarization was found to be highly effective in reducing the population of fungi, bacteria and actinomycetes. The pre-solarized microbial population was reduced from 25.68×104 to 4.80×104 (fungi), 20.78×106 to 5.66×106 (bacteria) and 31.60×105 to 4.40×105 (actinomycetes) per gram of soil after solarization (Table 4). In solarized soil the lowest population of fungi (4.8×104 g-1 soil), bacteria (5.66×106 g-1 soil) and actinomycetes (4.4×105 g-1 soil) was recorded at 0 days after solarization while the highest population of fungi (6.84×104 g-1 soil), bacteria (8.86×106 g-1 soil) and actinomycetes (10.44×105 g-1 soil) was recorded at 90 days after solarization. The observations clearly revealed that the population of fungi, bacteria and actinomycetes increased significantly from 0 to 90 days after solarization, but it was significantly reduced when compared with non-solarized soil at different intervals (Table 5). Decrease in the microbial population has also been reported by several workers (Ashrafi et al. 2010; Wadi 1999). Sharma & Sharma (2002b) have reported that high temperature under a 25-μm-thick mulch had a lethal effect on the fungal, bacterial and actinomycetes population under irrigated soil conditions. The observations in the present study reveal that the populations of fungi, bacteria and actinomycetes were significantly increased from 0 to 90 days after solarization, though they were significantly reduced when compared with non-solarized soil at different intervals. These findings are almost similar to the findings of several workers (Chaube & Singh 1991; Tjamos & Paplomatas 1988). Direct hydrothermal effect is probably the major mechanism for inactivation of microbial propagules as a

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Fig. 3 Effect of soil solarization on seedling length of cauliflower

consequence of raised soil temperatures and has a most pronounced lethal effect on a broad spectrum of soil organisms. The significant reduction in the microbial population in solarized soil over non-solarized soil after 90 days of solarization can be attributed to an initial drastic reduction of microbial inoculum during solarization and limited re-infestation by the microorganisms. There was a slow increase of the microbial population from 0 to 90 days after solarization. The observations of this experiment are in accordance with ecology and ecosystems where population and communities interact in the food chain. Nematode population The nematodes identified in both solarized as well as non-solarized soils were Helicotylenchus, Tylenchorhynchus, Tylenchus, Hoplolaimus and free-living. The data (Table 6) reveal that soil solarization was highly effective in reducing the initial total nematode population of 5650 in pre-solarized soil to 152 after solarization. The reduction of the nematode population in solarized soil was more than 97%. The maximum reduction in nematode population was observed in Tylenchus (97.42%), followed by free-living (97.28%), Tylenchorhynchus (97.25%), Hoplolaimus (97.14%) and Helicotylenchus (97.07%) in solarized soil over pre-solarized soil. At 0 days after solarization the number of nematodes was 30.0 (Helicotylenchus), 27.7 (Tylenchorhynchus), 37.3 (Tylenchus), 17.7 (Hoplolaimus) Fig. 4 Effect of soil solarization on seedling vigor index of cauliflower

and 39.3 (free-living) in solarized soil as against 1068.0 (Helicotylenchus), 1121.0 (Tylenchorhynchus), 1346.7 (Tylenchus), 565.0 (Hoplolaimus) and 1513.3 (freeliving) in non-solarized soil. In solarized soil the lowest number of total nematodes (152.0) was recorded at 0 days after solarization, while the highest number of total nematodes (3284.7) was recorded at 90 days after solarization, thus showing an increasing population from 0 to 90 days after solarization. However, solarization significantly reduced the total nematode population even 90 days after solarization when compared with non-solarized soil (Table 7). These findings are in conformity with those of Barbercheck & Broembsen (1986), Lazarovits et al. (1991) and Kamra & Gaur (1998). The reduction in the number of nematodes and slow recovery after solarization may be due to sublethal heating of the nematodes in the soil profile, resulting in reduced potential, lower subsequent reproduction or egg hatching, and possibly induced bio-control. Increased growth response The seed germination percentage, seedling length and seedling vigor index in solarized soil was better than in non-solarized soil. The pooled data show that the seed germination percentage in solarized soil was 76.12% compared with 58.78% in non-solarized soil (Fig. 2). Seedling length (Fig. 3) and

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seedling vigor index (Fig. 4) were, respectively, 33.34 cm and 2537.84 in solarized soil compared with 24.33 cm and 1430.11 in non-solarized soil. The observations regarding the seedling length among the three nurseries were non-significant, indicating the effect of soil solarization up to the third nursery, i.e., up to 90 days after solarization. This is in close proximity to the results of Stapleton et al. (1985) and Matheron & Porchas (2010). Raj & Kapoor (1993) and Raj et al. (1997) recorded an increase in length of tomato, cauliflower and other vegetable seedlings grown in solarized soil over nonsolarized soil. Katan (1995) believes that secretion of more amino acids by the roots of plants grown in solarized soil enhances plant growth. These reports correspond to a phenomenon known as increased growth response (IGR) that has been attributed to several mechanisms, including increases in nutrient levels in the soil, stimulation of beneficial organisms and control of pathogens. In the present study increased nutritional status, decreased microbial, nematode and weed population may be responsible for the enhanced germination, increased seedling length and finally better seedling vigor index. Solarization can induce IGR also by enhancing biocontrol processes and by reduction in soilborne pathogens (Le Bihan et al. 1997; Sofi et al. 2009). Sofi et al. (2009) reported a synergistic interaction between soil solarization and the application of biocontrol agents that increased number of cauliflower seedlings and improved the seedling vigor index. It is recommended that the field be solarized just before a crop is sown so that it can benefit from the treatment in the rotation cycle. Then, the land is left for three or four succeeding crops and then solarized again prior to planting the same crop. The method is simple, safe, and effective, leaves no toxic residues, and can be easily used on a small or large scale. Soil solarization has the long-term benefits of increased nutritional status, and decreased microbial, nematode and weed population of the soil, which finally leads to better plant vigor.

References Ashrafi, S. J., Rastegar, M. F., & Saremi, H. (2010). Rosemary wilting disease and its management by soil solarization technique in Iran. African Journal of Biotechnology, 9, 7048–7057.

Phytoparasitica (2014) 42:1–11 Barbercheck, M. E., & Broembsen, S. L. (1986). Effects of soil solarization on plant-parasitic nematodes and Phytophthora cinnamomi in South Africa. Plant Disease, 70, 945–950. Bremner, J. M., & Mulvaney, C. S. (1982). Nitrogen- total. In: R. H. Miller & D. R. Keeney (Eds.) Methods of soil analysis, Part 2, Chemical and microbiological properties (2nd ed.). Madison, WI, USA: American Society of Agronomy, Inc. Chaube, H. S., & Singh, U. S. (1991). Plant disease management, principles and practices. Boca Raton, FL, USA: CRC Press. Chauhan, Y. S., Nene, Y. L., Johansen, C., Haware, M. P., Saxena, N. P., Singh, S., et al. (1988). Effect of soil solarization on pigeonpea and chickpea. Research BulletinICRISAT, 11, 16. Elmore, C. L., Stapleton, J. J., Bell, C. E., & Devay, J. E. (1997). Soil solarization: A nonpesticidal method for controlling diseases, nematodes and weeds. University of California, Division of Agriculture and Natural Resources, Publication 21377. Gamliel, A., & Katan, J. (1991). Involvement of fluorescent pseudomonads and other microorganisms in increased growth response of plants in solarized soils. Phytopathology, 81, 494–502. Gelsomino, A., & Cacco, G. (2006). Compositional shifts of bacterial groups in a solarized and amended soil as determined by denaturing gradient gel electrophoresis. Soil Biology & Biochemistry, 38, 91–102. Ioannou, N. (1999). Management of soil-borne pathogens of tomato with soil solarization. Technical Bulletin Cyprus Agricultural Research Institute, 205, 9. Kamra, A., & Gaur, H. S. (1998). Control of nematodes, fungi and weeds in nursery beds by soil solarization. International Journal of Nematology, 8, 46–52. Katan, J. (1987). Soil solarization (pp. 77-105). In: I. Chet (Ed.), Innovative approaches to plant disease control. New York, NY: John Wiley and Sons. Katan, J. (1995). Soil solarization: A non-chemical tool in plant protection. Journal of Mycology and Plant Pathology, 25, 46–47 (abstr.). Knudsen, D., Peterson, G. A., & Pratt, P. F. (1982). Lithium, sodium and potassium. In: R. H. Miller & D. R. Keeney (Eds.) Methods of soil analysis, Part 2, Chemical and microbiological properties. Madison, WI, USA: American Society of Agronomy, Inc. Lazarovits, G., Hawke, M. A., Tomlin, A. D., Olthof, T. H. A., & Squire, S. (1991). Soil solarization to control Verticillium dahliae and Pratylenchus penetrans on potatoes in central Ontario. Canadian Journal of Plant Pathology, 13, 116– 123. Le Bihan, B., Soulas, M. L., Camporota, P., Salerno, M. I., & Perrin, R. (1997). Evaluation of soil solar heating for control of damping-off fungi in two forest nurseries in France. Biology and Fertility of Soils, 25, 189–195. Matheron, M. E., & Porchas, M. (2010). Evaluation of soil solarization and flooding as management tools for Fusarium wilt of lettuce. Plant Disease, 94, 1323–1328. Metson, A. J. (1961). Methods of chemical analysis for soil survey samples. New Zealand, DSIR, Soil Bureau Bulletin, 12. Wellington, New Zealand: Government Printer. NHB. (2011). Indian horticulture database. National Horticultural Board, Ministry of Agriculture, Government of India.

Author's personal copy Phytoparasitica (2014) 42:1–11 Olsen, S. R., & Sommers, L. E. (1982). Phosphorus. In: R. H. Miller & D. R. Keeney (Eds.) Methods of soil analysis, Part 2, Chemical and microbiological properties. Madison, WI, USA: American Society of Agronomy. Orchard, T. (1977). Estimating the parameters of plant seedling emergence. Seed Science Technology, 5, 61–69. Overman, A. J., & Jones, J. P. (1986). Soil solarization, reaction and fumigation effects on double cropped tomato under full bed mulch. Proceedings of the Florida State Horticultural Society, 99, 315–318. Raj, H., Bharadwaj, M. L., & Sharma, N. K. (1997). Soil solarization for the control of damping-off of different vegetable crops in nursery. Indian Phytopathology, 50, 524–528. Raj, H., & Kapoor, I. J. (1993). Soil solarization for the control of tomato wilt pathogen (Fusarium oxysporum Schl.). Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz, 100, 652–661. Rao, V. K., & Krishnappa, K. (1995). Soil solarization for the control of soil-borne pathogen complex with special reference to Meloidogyne incognita and Fusarium oxysporum f.sp. ciceri. Indian Phytopathology, 48, 300–303. Schnitzer, M. (1982). Organic matter characterization. In: R. H. Miller & D. R. Keeney (Eds.) Methods of soil analysis, Part 2, Chemical and microbiological properties. Madison, WI, USA: American Society of Agronomy.

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11 Sharma, M., & Sharma, S. K. (2002a). Effect of organic amendments on soil microbial population in relation to Dematophora necatrix causing white root rot of apple. Plant Disease Research, 17, 9–15. Sharma, M., & Sharma, S. K. (2002b). Effect of soil solarization on soil microflora with special reference to Dematophora necatrix in apple nurseries. Indian Phytopathology, 55, 158–162. Sofi, T. A., Tewari, A. K., Ganai, N. A., & Ahangar, F. A. (2009). Soil solarization integrated with eco-friendly practices to manage cauliflower damping-off and seedling vigour. Journal of Mycology and Plant Pathology, 39, 252–256. Stapleton, J. J., Bert, L., & Devay, J. E. (1987). Effect of combining soil solarization with certain nematicides on target and non-target organisms and plant growth. Annual Applied Nematology, 1, 107–112. Stapleton, J. J., Quick, J., & Devay, J. E. (1985). Soil solarization: effects on soil properties, crop fertilization and plant growth. Soil Biology and Biochemistry, 17, 369–373. Tjamos, E. C., & Paplomatas, E. J. (1988). Long-term effect of soil solarization in controlling Verticillium wilt of globe artichokes in Greece. Plant Pathology, 37, 507–515. Wadi, J. A. (1999). Effect of soil solarization on some soil microorganisms and tomato growth. Egyptian Journal of Horticulture, 26, 167–176.