﻿178 
  INTRODUCTION 
  TO 
  BOTANY 
  

  

  The 
  best 
  way 
  in 
  which 
  to 
  illustrate 
  what 
  modern 
  plant 
  

   breeding 
  means 
  is 
  to 
  give 
  a 
  few 
  instances 
  of 
  the 
  methods 
  

   actually 
  employed. 
  

  

  169. 
  Wheat 
  breeding 
  : 
  its 
  purpose. 
  Wheat 
  is 
  the 
  most 
  im- 
  

   portant 
  gram 
  for 
  human 
  food 
  in 
  temperate 
  climates, 
  and 
  North 
  

   America 
  is 
  by 
  far 
  the 
  greatest 
  wheat-producing 
  region 
  in 
  the 
  

   world. 
  The 
  annual 
  value 
  of 
  the 
  crop 
  of 
  the 
  United 
  States 
  

   ranges 
  from 
  $250,000,000 
  to 
  $500,000,000. 
  Scientific 
  wheat 
  

   breeding 
  began 
  barely 
  a 
  century 
  ago, 
  and 
  has 
  progressed 
  more 
  

   in 
  the 
  United 
  States 
  since 
  1890 
  than 
  during 
  all 
  our 
  previous 
  

   history. 
  r 
  

  

  Some 
  desirable 
  qualities 
  to 
  be 
  sought 
  in 
  wheat 
  breeding 
  are 
  

   (1) 
  large 
  yield 
  per 
  acre 
  ; 
  (2) 
  good 
  quality 
  for 
  bread-making, 
  

   requiring 
  a 
  high 
  per 
  cent 
  of 
  the 
  tenacious 
  gluten, 
  the 
  main 
  

   protein 
  portion 
  of 
  the 
  grain 
  ; 
  (3) 
  hardiness, 
  shown 
  in 
  winter 
  

   wheat, 
  in 
  resisting 
  severe 
  winter 
  conditions 
  ; 
  (4) 
  resistance 
  

   to 
  rust; 
  (5) 
  resistance 
  to 
  drought. 
  

  

  Not 
  all 
  of 
  these 
  qualities 
  can 
  be 
  combined 
  in 
  the 
  highest 
  

   degree 
  in 
  any 
  one 
  variety, 
  and 
  therefore 
  every 
  region 
  should 
  

   grow 
  the 
  particular 
  kind 
  of 
  wheat 
  best 
  suited 
  to 
  the 
  local 
  

   conditions 
  and 
  market. 
  About 
  eight 
  species 
  of 
  wheat 
  are 
  

   recognized, 
  and 
  the 
  number 
  of 
  varieties 
  of 
  these 
  species 
  is 
  

   very 
  large. 
  

  

  170. 
  Wheat 
  breeding 
  : 
  the 
  method. 
  In 
  order 
  to 
  show 
  how 
  

   carefully 
  the 
  process 
  of 
  wheat 
  breeding 
  is 
  managed 
  in 
  our 
  

   best 
  agricultural 
  experiment 
  stations, 
  the 
  principal 
  steps 
  of 
  

   the 
  operation 
  are 
  here 
  given 
  in 
  the 
  barest 
  outline, 
  omitting 
  

   many 
  most 
  important 
  details. 
  1 
  

  

  1. 
  Ten 
  thousand 
  large, 
  sound 
  kernels 
  of 
  a 
  single 
  good 
  

   variety 
  of 
  wheat 
  are 
  selected 
  and 
  planted 
  in 
  hills, 
  and 
  each 
  

   hill 
  is 
  numbered. 
  About 
  95 
  per 
  cent 
  of 
  the 
  poorer 
  plants 
  are 
  

   rejected 
  as 
  they 
  mature. 
  When 
  mature, 
  the 
  heads 
  of 
  each 
  of 
  

   the 
  chosen 
  plants 
  are 
  put 
  together 
  in 
  an 
  envelope 
  and 
  preserved. 
  

  

  1 
  See 
  Bulletin 
  62, 
  University 
  of 
  Minnesota 
  Agricultural 
  Experiment 
  

   Station, 
  and 
  Bulletin 
  29, 
  Division 
  of 
  Vegetable 
  Physiology 
  and 
  Pathology, 
  

   U.S. 
  Dept. 
  Agr. 
  

  

  