The effect of weather on the concentration of pollen within sugar‐beet seed crops

Abstract

SUMMARYThe concentration of pollen in the air within diploid open‐pollinated sugar‐beet seed crops at Broom's Barn Experimental Station increased between 05.00 and 09.00 G.M.T. as relative humidity became less than 90%, was greatest between 09.00 and 11.00, when relative humidity was c. 75%, and gradually decreased towards evening. The average pollen concentration during 24 h periods ranged from 170 to 12400/m3 being greatest on fine, windy, dry days after periods of cooler weather. Rain during the morning washed pollen out of the air and damaged developing anthers, but rain in the late afternoon following a sunny morning seemed hardly to affect the pollen catch, while rain at night sometimes caused an immediate temporary increase in pollen concentration. Most pollen was released between 27 June and 31 July in all years (1965‐7); more in the first than in the second half of July. 1965 was cool and damp, 1967 warm and dry, 1966 warm and dry early, and cool and wet late. The total pollen catch in 1965 was 83% and in 1966 31% of that in 1967 but the percentage germination of seed harvested in the 3 years was similar.The total pollen catch on a trap 230 m east of the 1965 crop was c. 1% of the catch within the crop on days with gusty westerly winds and the catch on a trap c. 46 cm above the 1966 crop averaged 78.6% of that at the level of most flowers.