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The relationship between sowing rate, seedling density. And seed yield of Trikkala sub clover on farm paddocks in South West Victoria

P. M. Schroder

Department of Agriculture and Rural Affairs, P.O. Box 406, Hamilton, Victoria 3300

Following an extension programme which encouraged farmers to increase their sowing rate of Trikkala sub clover from an average of 1.9 kg/ha (1) to 10 kg/ha it was considered important to measure improvements in seedling density and seed yield in farm paddocks.


Establishment of Trikkala sub clover was assessed in winter 1985, 6-12 weeks after sowing, by counting seedlings in fifty 25dm2 quadrats positioned at random in each of 44 paddocks. Virtually all the paddocks had been sown using conventional cultivation methods. The paddocks assessed were selected from those that farmers had discussed with me either before or after sowing. The sowing rates used ranged from 2 to 13 kg/ha, 11 being sown at no more than 5 kg/ha and 18 being sown at 10 kg/ha or more. Fourteen of the 44 paddocks were selected to cover the range of seedling densities measured and the seed yield was measured in summer 1985/86 using the method outlined by Schroder (2).

Because of the limited range of sowing rates linear regression analysis was used to determine the relationships between the variables. The line was forced through the origin.

Results and discussion

The relationship between Trikkala seedling density T (no./m2) and sowing rate S (kg/ha) was:

T = 3.5 S (R2 = 0.89 **) (+ 0.2)

and between seed yield X (kg/ha) and seedling density was:

X = 3.02 T (R2 = 0.91 **) (+ 0.3)

Where the sowing rate recommended in the extension programme (10kg/ha) was used, the equations predict that the Trikkala seed yield at the end of the first growing season would be 106 kg/ha, substantially more than if the average sowing rate before the extension programme was used (1.9 kg/ha) but still well below the minimum (200 kg/ha) considered necessary for satisfactory growth and survival of sub clover (3). While experience has shown that seedling density can be consistently increased by 50% with better management at sowing, it is likely that greater gains in seed yield will he made by substantially increasing seed yield per seedling. Reducing competition from weedy plants will he the most important factor in achieving this (4). Sowing pastures by direct drilling (5), rather than conventional methods, is one way this can be achieved.

1. Schroder, P.M. (1987). Proc. 4th Aust. Agron. Conf. Melb. 207.

2. Schroder, P.M. (1987). Proc. 4th Aust. Agron. Conf. Melb. 205.

3. Carter, E.D., Cochrane, M.J. (1985). Proc. 3rd. Aust. Agron. Conf. Hobart. 217.

4. Schroder, P.M. (1987). Proc. 4th Aust. Agron. Conf. Melb. 206.

5. Schroder, P.M. (1987). Proc. 4th Aust. Agron. Conf. Melb. 208.

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