Effects of shelter on the growth of turnips and sugar beet.
Swedes cv. Victory and sugar beet cv. Klein E were grown at 2 sites in S.E. England and protected by a N.-S. screen with 50% permeability; the height of the screen was 1.22 m for swedes and 2.44 m for sugar beet. Plants from sheltered crops had greater leaf area and initially yielded more DM than exposed crops, but by the end of the growing season there were no significant yield differences. In sugar beet, relative water content of sheltered plants generally exceeded that of exposed plants after overnight recovery or during the day when wind was from the direction of the shelter. Where relative water content was <80%, stomal apertures were smaller in the exposed plants. Soil water content was highest in the most sheltered treatment except for about 21 days prior to maximum water deficit. Potential evapotranspiration was lower in the sheltered treatments. There was no marked difference between treatments in soil water use by sugar beet over the experiment as a whole, although there were indications of differences at times during the experiment. Late in the trials when crop yields were converging, the exposed plants had higher RGR, relative leaf growth rate and NAR than sheltered plants, and the dependence of crop growth rate on LAI favoured the exposed plants.