Agriculture Reference
In-Depth Information
Fig. 4.35.
Stages in the life cycle of onion plants with particular reference to flowering.
Unusual or reversionary developmental processes are shown by broken lines.
nullify inflorescence induction. Processes occurring at the shoot apex within
bulbs can be observed only by destructive sampling, so progress in these phases is
difficult to assess.
Because of: (i) the changing environmental needs of different phases in the
sequence; (ii) differences in the rate of progress through each phase, depending
on cultivar and bulb size; and (iii) the possibility of reversion or deviation from
the normal pathway of development at various points along the route, reports
of the effects of environmental factors on flowering may give apparently
contradictory results, and it is difficult to predict the outcome of a particular
combination of agronomic conditions on flowering. Nevertheless, a clear
general pattern of environmental requirements for each stage in the cycle of
Fig. 4.35 is known, even though quantitative information is limited to that
from experiments on a few cultivars at each stage. Therefore, given careful
experimentation with sufficiently detailed observation, it is possible to
understand flowering behaviour in field conditions even if it cannot yet be
predicted without experimentation.
