Production and persistence of white clover varieties under different climatic conditions

M. Zimková and V. Smajstrla

Grassland Research Institute/Mládeznicka 36/974 21 Banska Bystrica/Slovakia

Introduction
Materials and methods
Results and discussions
References

Introduction

White clover (Trifolium repens) plays a very important role in well established and properly managed pastures. Its importance is increasing further as grass/clover swards become an economically viable and environmentally friendlier option to heavily N-fertilized grass swards.

Materials and methods

The field trials were established in 1991 and 1992. White clover varieties as listed in Table 1 and 4 were sown in two different regions of Slovakia: at Nitra (Site Agrokomplex), 145 m a.s.l., average annual temperature 9.6°C (during growing season, 16.3°C), annual rainfall 595 mm (during growing season, 333 mm) and at Banská Bystrica (Site Suchý vrch -Radvan), 450 m a.s.l., annual temperature 6.3°C (during growing season, 13.5°C), annual rainfall 848 mm (during growing season, 451 mm).

The first series of trials was sown in 1991 (at Nitra on 22 April and at B. Bystrica on 30 May) and the second series in 1992 (at B. Bystrica on 5 May).

In the second series all the British varieties (but substituting Nesta for Sabeda) were resown and also the Belgian variety Merwi, Czech varieties Pastevec and Hajek and mixtures of perennial ryegrass cv. Merganda + Merwi and cv. Merlinda + Merwi.

After sowing (rates 6 and 9 kg/ha in 1991 and 1992 respectively) the establishment, performance and weed infestation were investigated. Two cuts were made to control weeds but yields were recorded for the third cut at B. Bystrica and the third and fourth cuts at Nitra in 1991. In 1992 the trials with British varieties of white clover continued at Nitra but had to be re-established at B. Bystrica (land transformation to the private owners). The first recorded yield is thus from 26 May 1993 (not shown).

Soil analyses were as follows: Nitra-pH 6.8/103mg P/kg, 118 mg K/kg, clay soil; B. Bystrica 1991 Site A - pH 6.7, 4.7 mg P/kg/71 mg K/kg/rendzina soil; B. Bystrica 1992 Site B - pH 6.8/8.7 mg P/kg and 107 K/kg/rendzina soil.

Results and discussions

In 1991 the establishment of white clover varieties was better at the lowland Nitra site. Germination was even and there was good sward density. In the submontane region the establishment was uneven and bare spaces were evident because of the late sowing date. Weed infestation was rather high at both sites. The main weeds in the lowland swards were Galinsoga parviflora, Cirsium spp. and Stachys recta. Cirsium spp. dominated at the submontane site.

At the B. Bystrica 1992 sown site all varieties of white clover germinated evenly and there were fewer bare spaces in the sward than in the previous year. The dominant weeds were Chenopodium album and Stachys recta.

Large numbers of plants per decimetre (dm²) were evident for Donna/S184 and Menna (79, 64 and 55, respectively). Donna and Olwen achieved the highest total leaf area per dm² (355 and 337cm²) in 1991.

White clover yields were higher at the lowland site (Table 1) and in accordance with previous results (Smajstrla, 1985). Belgian variety/cv. Blanca showed good yields previously in northern Slovakia (Kasper/1985).

Table 1 DM yields (t/ha) of white clover varieties in 1991 and 1992

Varieties	Nitra (1991)			B. Bystrica	Nitra
	1/9	15/10	Total	27/9/1991	Total, 1992
Alice	2.44	0.41	2.85	2.05	2.23
Donna	3.16	0.60	3.76	3.15	1.75
Gwenda	2.04	0.88	2.92	2.85	1.02
Menna	3.21	0.64	0.85	2.25	1.81
Olwen	2.49	0.61	3.10	2.85	2.38
S 184	2.11	0.13	2.24	0.85	1.64
Sabeda	3.24	0.74	3.98	2.05	1.64
Siwan	2.54	0.55	2.99	1.60	1.95

The summer of 1992 was extremely hot and dry (Table 2) and all varieties were desiccated and stunted/so the third cut could not be taken.

Table 2 Average air temperatures (ºC) and rainfall (mm) from June to August, 1991 and 1992

Year	Air temperatures (°C)			Rainfall (mm)
	June	July	August	June	July	September
1991	15.8	19.6	17.3	100	90	58
% of Long-Term Average	-	-	-	113	117	84
1992	17.8	19.0	22.6	84	51	3
% of Long-Term Average	-	-	-	94	66	5

Because of extreme summer conditions in 1992 the third cut on 13 October at the B. Bystrica 1992 sown site could not be measured on the pure-sown clover plots. Only the yields of the ryegrass/white clover mixtures were recorded (Table 3).

Table 3 DM yield (t/ha) of ryegrass/white clover mixtures at the third cut/1992

Mixture	B. Bystrica
	13/10/1992
Merganda + Merwi	0.99
Merlinda + Merwi	1.38

According to Swiss varieties evaluation (Charles and Joggi, 1988; 1 to 9 point scale, 1 = the best) the general vigour and persistence were recorded on 22 April, 1993 (see Table 4).

Table 4 Characteristics of white clover varieties (1-9 points)

Variety	Country	Vigour	Persistence	Competitiveness in mixture
Alice	UK	2.7	2.6	-
Donna	UK	2.8	2.7	-
Gwenda	UK	2.6	2.5	-
Menna	UK	2.9	2.7	-
Nesta	UK	2.4	2.3	-
Olwen	UK	2.6	2.5	-
S 184	UK	2.9	2.5	-
Siwan	UK	2.3	2.7	-
Merwi	B	2.1	2.1	-
Pastevec	CS	2.3	2.6	-
Hájek	CS	2.2	2.5	-
Merganda + Merwi	B	3.0	3.4	2
Merlinda + Merwi	B	2.6	2.6	1

White clover cv. Merwi performed better in mixture with perennial ryegrass cv. Merlinda than in mixture with cv. Merganda.

Table 5 Average height of the plants in monoculture and mixture swards

Variety Mixture	Height	of plants
	22/5/1993
	Grass	Legume
Merwi	-	8-12
Merganda	17-19	-
Merlinda	21-25	-
Merganda + Merwi	24-27	14-15
Merlinda + Merwi	20-25	11-13

On average, Merwi was 2-3 cm higher in mixture than in pure culture. Both grass/clover mixtures were of optimal density without any bare spaces. Evaluation of the clover varieties will continue over the next two years and root measurements will also be determined.

References

CHARLES, J.P. and JOGGI, D. (1988) Essais variétaux de ray-grass anglais (Lolium perenneL.) et de ray-grass hybride (L.x. hybridum Hau). Revue suisse Agric, 20, 35-38.

KASPER, J. (1984) Sledovanie vytrvalosti niektorých druhov tráv a dateliny plazivej. Annual report of GRI Banská Bystrica.

SMAJSTRLA, V. (1985) Vyuzitie rôznych odrôd tráv a datelinovín. Annual Report of GRI Banská Bystrica.