Love and Craig: Small Grain Investigations 



69 



from certain of the tall lines to see 

 whether they reproduced shorter off- 

 spring than did the tall plants. Each 

 year the grain has been saved so that 

 further studies may be made if desired. 

 The effect of thus selecting plants 

 may be shown by the following general 

 summary showing four years' w^ork. 

 In this summary the height of the 

 parent plants is given, together with 

 the height of the resulting line in each 

 case. The average of the parent plants, 

 as well as the average height of the 

 offspring, is given for each year. 



From this table it is clear that, al- 

 though the average height of the parent 

 plants selected differed by 25.7 centi- 

 meters, the offspring from the tall and 

 short parents gave the same average 

 height. It is clear then that for oats 

 at least it is not possible in a few years 

 to change the type by selecting parent 

 plants within a pure line. 



VARIATION AND CORRELATION 



The variation and correlation studies 

 have been made first- to determine the 

 amount and nature of variation and 

 correlation with oats and wheat in 

 order to see what use such information 

 may be to plant breeding. A second 

 line of study has been to determine 

 what effect environment has upon the 

 variation and correlation constants. 

 These studies have been of a statistical 

 nature and have dealt with such char- 

 acteristics as height of plant, number 

 of kernels, weight of kernels, ntmiber 

 of spikelets. and the like. They have 

 shown brief! V that:- 



Environmental conditions such as 

 exist in different years cause changes 

 in the means. Conditions that gener- 

 ally result in reduction of plant yield 

 also result in reduction of height, 

 nimiber of kernels, and number of 

 culms, but in increase in size of kernels. 



Yield is reduced by decrease in 

 number of kernels produced, rather 

 than by decrease in their size. 



Variability decreases with decrease 

 in the means. 



Correlations are more or less respon- 

 sive to environmental conditions, and 

 may be divided into fluctuating and 

 stable, according to their behavior 

 under differing environments. 



There are high, positive, and fairly 

 stable coiTclations between average 

 height of plant and (a) total and aver- 

 age yield, (b) total and average number 

 of kernels produced, (c) average nimiber 

 of spikelets per culm; the correlations 

 between average height of plant and 

 (d) average weight of kernels, (e) 

 number of culms, are fluctuating, being 

 high or low on occasion. 



There are high, positive, and stable 

 correlations betw^een total yield and 

 (a) culm yield, (b) total and average 

 kernel production, (c) spikelet produc- 

 tion, (d) culm production. 



The average kernel weight is not cor- 

 related closel}?- and consistently with 

 any other character here considered, 

 except average cukn yield, with which 

 the correlation is fairly high and fairly 

 consistent. 



The average number of spikelets per 

 culm per plant is correlated (a) fairly 

 highly with the average number of 

 kernels per spikelet ; (6) apparently very 

 highly with number of kernels per culm; 

 (c) very highly and stably with average 

 height of plant and total yield; and (d) 

 in a fluctuating manner with kernel 

 weight. 



Thle correlations between number of 

 culms per plant and (a) height, (6) 

 culm yield, (c) number of kernels, are 

 fluctuating, varying greatly from high 

 to low; between nirmber of culms per 

 plant and (d) total yield they are high, 

 positive, and stable; between number 

 of culms per plant and (<?) average 



2 Memoir No. 3, Cornell University Agricultural Experiment Station. 



