28 Colorado Experiment Station 
when the surrounding plants would fail completely on account of 
insect injury. 
CLIMATIC CONDITIONS, HEAT AND ITS RELATION TO SEED 
YIELDS 
As previously mentioned, it has been observed frequently that 
alfalfa branches which bend over and lie closely to the bare ground 
sometimes set heavily with seed, when the balance of the same plant 
sets poorly. These branches close to the ground are not only ex- 
posed to hot sunlight, but are also exposed to radiated heat from 
the soil below. A notable instance of this kind occurred on the 
Experiment Station Farm at Ro'cky Ford in the fall of 1919, 
An irrigation ditch that had not been used all summer had a row 
of alfalfa growing on its north bank. The ditch had been cleaned 
out with a ditching “A.” This made a dry, sandy, sloping bank 
next to the alfalfa row. The lower branches from this row dropped 
over into the ditch. These branches thruout the length of the 
ditch (about 300 feet) all set heavily with seed. The branches nearest 
the ground were best filled with seed. The balance of the branches 
of the plants in the row was practically barren of seed. 
Plants developed from a single mother plant, thus producing a selected strain showing 
great uniformity in their development and habits of growth. The above plants all came 
from one selected strain. 
