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Abstract
The growth of 8 semi-commercial crops of sugar beet on the Canterbury Plains was monitored during the 1981-82 season. Sugar yields ranged from 9 to 15 t/ha. The highest yielding crop intercepted 1166 MJ/m2 of photosynthetically active radiation. The major :eason for yields of less than 15 tlha was reduced radiation interception (up to 376,10) because of small leaf areas. This was probably caused by drought in most crops, but shortage of nitrogen, variable plant populations, weeds, and virus attack were also implicated at some sites. The efficiency of converting intercepted radiation to dry matter averaged 2.3 in 6 crops, but was about 2.0 in the other 2 crops (one affected by drought, the other by virus). Harvest index in most crops averaged 0.57, but was slightly lower in crops grown on the more fertile soils. Sugar yields were generally unaffected by soil type, but tops were heavier on the deeper soils. As the autumn progressed, top yields on the deep soils decreased and contained a higher proportion of crowns.