Abstract
Effects of sowing date, plant population and planting method on the accumu-lation of leaf area index and dry matter yields in sugar beet (Beta vulgaris L., cv. Amazon) were investigated during 1982/83 season at Lincoln College, New Zealand. Both the mid-August sowing and the transplanted beet had higher leaf area index than that of the mid-September sowing and the seed-sown beet, respec-tively, only until January harvest. A population of 10 plants m-2 had a significantly higher leaf area index than a population of 6 plants m-2 throughout the growing sea-son.
Total dry matter or root dry matter yields of the mid-August sowing or the transplanted beet were significantly greater than those for the mid-September sow-ing or the seed-sown beet, respectively. A population of 10 plants m-2 produced higher dry matter yields than a population of 6 plants m-2, Final root DM yield was 19.3% greater at the higher density.
INTRODUCTION
Empirical research indicates that sugar beet responds positively to the extension of the growing season, and this usually leads to the increased yield (Martin, 1983). However, even early-sown crops fail to intercept about 40% of the radiation incident over the whole season (Scott et al., 1973). This coupled with the inability of the seed to germinate at low temperatures, tends to limit what can prob-ably be achieved by still earlier sowings. Transplanted breed may be established ear-lier to extend the growing season. Because of the limited research information avail-able, it was desirable to investigate how early transplanted beet can be established for successful yields. Plant population influences plant size, root weight and sugar content (Hussain, 1990). Experiments on the effect of plant population on sugar beet production indi-
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cated that, in different environments, popu-lations between 75,0(X) to 100,000 plants ha-1 gave optimum yields (Hull and Jaggard, 1971), In the United Kingdom, Wickens (1982) studied a range of populations (45,000-70,000 plants ha-1) in both seed-sown and transplanted beet and reported little differences in yield between the plant populations, irrespective of the planting method. In New Zealand, no research work has been reported on the growth and dry matter yields of the transplanted beet. Therefore, the objective of this study was to examine the effects of sowing date, plant population and planting method on the leaf growth and dry matter yields in sugar beet.
