Longevity of pollen and stigmas of grasses: buffalograss, Buchloe dactyloides (Nutt.) engelm., and corn, Zea mays L

Studies to determine the longevity of pollen and stigmas of buffalograss and corn were conducted at Lincoln, Neb., during 1944 and 1945. Data on longevity of pollen were obtained from daily pollinations with pollen stored under different conditions, while data on the duration of receptiveness of stigmas were obtained from pollinations made with fresh pollen to stigmas of different ages. Buffalograss pollen stored in the spike under a temperature of 40 degrees F and a relative humidity of 90% effected fertilization for 7 days in both years. Free pollen stored in a beaker under the same temperature and humidity remained viable for 6 days in 1944 and 8 days in 1945. These same treatments were applied to corn pollen in 1944 and 1945. Corn pollen stored in the tassel effected fertilization for 9 days in 1944 and 8 days in 1945. No pollinations were made after 8 days in 1945 as a result of heavy rainfall. Corn pollen stored in a beaker remained viable in part for 8 days. Under this treatment a very good set of kernels was obtained the first 2 days with the viability decreasing rapidly thereafter. Pollen refrigerated in the inflorescence with both buffalograss and corn was more effective over a period of several days than pollen refrigerated in a beaker. Three additional treatments involving temperatures of 77 degrees to 113 degrees and relative humidities of 30 to 70% were ineffective in extending life of buffalograss or corn pollen. Corn pollen stored in pollinating bags in direct sunlight under a maximum temperature of 96 degrees F was effective in fertilizing silks for only 3 hours, while pollen stored in the shade of the plants under a maximum temperature of 86 degrees F remained viable for 30 hours. Cool temperature and high relative humidity appear to be important factors in extending the life of grass pollen. Receptivity of buffalograss stigmas remained fairly high for 13 days, after which time it decreased rapidly until no seed was produced on the twenty-first day. Duration of receptiveness in corn silks extended over a period of 24 days. Two- to 12-day-old-silks set seed rather uniformly, averaging 60%. Seed setting decreased from 41% on silks 14 days old to only 2% on silks 24 days old. The duration of receptivity of stigmas was 5 days more in corn than in buffalograss, The peak of receptivity occurred on the fifth day in buffalograss and on the eighth day in corn. It was found that with both buffalograss and corn the stigmas continued to grow in length until pollen was applied. Stigmas were observed to grow to lengths of 1 inch in buffalograss and 12 inches in corn.