Environmental control of growth, flowering and yield of lentil and chickpea in Saskatchewan
Date
1991
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Degree Level
Doctoral
Abstract
Yield of a crop depends on growth and developmental responses
to various environmental factors. Agronomic practices for high yield
of two new crops of Saskatchewan, lentil (Lens culinaris Medik.) and
chickpea (Cicer arietinum L.), must be based on these responses to
variations of the local climate. Controlled environment and field
studies were conducted: 1) to determine the effects of variations in
temperature, soil moisture and radiation intensity on physiological
characteristics and growth of Laird lentil and Cheston chickpea; 2)
to determine the effects of temperature and photoperiod on time to
first flower in five genotypes of lentil; and 3) to compare the
efficiency of the degree-day, rate-factor and equivalent hours of
maximum net photosynthesis (EHMNP) models for predicting time of
first flower in the same five lentil genotypes.
The optimum temperature for net photosynthetic rate (Pn) of
both lentil and chickpea was around 18°C. The decline of Pn at high
temperatures was accompanied by increases in respiration (R) and
transpiration (E1 rates. Rates of all these physiological processes
decreased as temperatures dropped below the optimum temperature.
Exposure to a single hot day (35°C) decreased Pn of lentil for 6 to
78 h, but did not decrease Pn of chickpea, whereas exposure to a
single cold night (0°C) decreased Pn of chickpea for 6 to 54 h and
Pn of lentil for 30 h, depending on growth stage. Both exposures
increased R only at a later growth stage of both species for at
least 78 h. A soil moisture deficit decreased Pn, E1 , stomatal
conductance (gs) and shoot water potential and accentuated leaf
senescence of both species. Chickpea produced higher seed yield than
lentil only at the lowest soil moisture supply, but both responded to irrigation. Radiation intensity did not affect gs, probably due
to the short interval between changes in radiation intensity.
Low temperature or short photoperiod increased time to
flower in all five genotypes of lentil in the controlled
environments. However, in the field flowering responses were related
to variation in temperature only.
All developmental models adequately predicted time of
first flower of five lentil genotypes within each of six field
environments. However, only degree-days and the two variations of
the rate-factor adequately predicted the time of first flower over
a wide range of environments. The rate-factor model based on mean
daily temperature and photoperiod was most successful, but must be
validated for each crop and each environment.
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Degree
Doctor of Philosophy (Ph.D.)
Department
Crop Science and Plant Ecology
Program
Crop Science and Plant Ecology