Townsend: Single-Germ Beet Seed 



353 



The first step in the solution of the 

 problem was to grow roots from seed 

 known to contain but a single germ. 

 These seeds germinated freely and the 

 plants grew vigorously, but since the 

 beet does not usually produce seed the 

 first year, it was necessary to store the 

 roots and plant them out the second 

 season for seed production. Hence the 

 first crop of seed produced from single- 

 germ seeds was in 1904. As was 

 expected, there was a wide variation in 

 the percentage of single-germ seeds on 

 the various seed-producing plants in 

 this experiment. In an effort to secure 

 single-germ strains and to prevent 

 crossing with plants of low potential 

 with regard to singleness of germ, the 

 most promising plants were covered 

 with closely woven cloth bags. By 

 promising plants is meant those that 

 indicated by the number of single or 

 isolated buds that the percentage of 

 single germ seeds would be high. 

 Further to insure the isolation of single 

 flowers, all clusters of buds were care- 

 fully removed from some branches and 

 the remaining buds were covered with 

 paper bags, to prevent them from 

 becoming pollinated with pollen from 

 flower clusters. In many cases the 

 pistils of the single flowers thus isolated 

 were hand pollinated as soon as they 

 were ready to receive the pollen. For 

 this purpose pollen from flowers stand- 

 ing alone, that is, not in clusters, was 

 used. Sometimes the pollen was taken 

 from the plant bearing the flower to be 

 pollinated, sometimes it was taken from 

 other plants, thereby producing both 

 close and cross fertilization. The work 

 of hand pollinating was done under 

 tents to guard further against unfavor- 

 able crossing. 



Subsequent improvements have shown 

 that in spite of all these precautions it 

 was possible for unfavorable crosses to 

 have been made by minute insects. 

 However, our results indicate that we 

 were in a measure successful in pro- 

 ducing the pollination desired. Indeed, 

 in our first generation of plants from 

 seeds selected without any knowledge 

 of their ancestry we found plants show- 

 ing a single flower tendency and con- 

 sequently a single-germ tendency to a 



marked degree. On the other hand, 

 in some of the plants from single-germ 

 seeds the flower clusters and consequent 

 multiple seed ball tendency so pre- 

 dominated that the percentage of single- 

 germ seeds was not appreciably greater 

 than in plants grown from multiple- 

 germ seeds. However, of the several 

 hundred roots produced from single 

 germ seeds over fifty produced upwards 

 of 25 per cent, single-germ seeds. 



RESULTS OF THE WORK 



The fifty showing the highest ntmiber 

 of single germs, as indicated in the bud 

 stage, were selected, trimmed and 

 isolated as thoroughly as possible in 

 the manner indicated above. Having 

 trimmed the best fifty plants, that is, 

 removed all the fiower clusters, leaving 

 only the single flowers, it was obviously 

 impossible for us to determine the 

 percentage of single-germ seeds in this 

 best fifty. The fifty-first plant selected 

 was not trimmed and produced 25 

 per cent, single-germ seeds. The next 

 best one had 213^2 per cent., the next 21 

 per cent., and so on down to normal. A 

 commercial beet seed field of 17 acres 

 in the same locality was carefully 

 searched and the plant having the highest 

 number of single-germ seeds showed 

 4.77 per cent, by actual count, the 

 average for the best ten in the com- 

 mercial field being 2.7 per cent. 



In the second generation the number 

 of single germ seeds was upYv^ards of 

 50 per cent, on the best plant and in 

 the third generation it was about 75 

 per cent. Therefore, continuing along 

 these lines, it is fair to assume that it 

 is only a matter of time w)ien a plant 

 bearing only single-germ seeds will be 

 produced. 



To sum up the work, it is apparent 

 that commercial beet plants normally 

 produce a few single-germ seeds. Our 

 problem was, by selection, to increase 

 the proportion of single-germ seeds 

 from less than 5% to 100. Our selected 

 plants are now producing about 75% 

 of single-germ seeds, and individual 

 plants in a few cases show a somewhat 

 higher percentage than this. The work 

 and progress of single-germ beet seed 



