Flowering response of diverse chickpea (Cicer arietinum L.) accessions to photoperiod

Knowledge of the time required for the initiation of flowering is important for chickpea adaptation in environments like western Canada, not only because flowering is a vulnerable stage of development but also it is a major factor affecting variation in crop duration. Temperature and photoperiod are the major environmental factors that determine time to flowering in many major crops. One hundred diverse chickpea accessions were examined under long-day (16/8 H day and night, respectively) and short day (10/14 H day and night, respectively) photoperiods for their flowering response. The temperature in the chambers was adjusted to 22/16 °C (day and night, respectively). Variability among the accessions for days to flowering, photoperiod sensitivity (defined as the delayed number of days to flowering under short-day photoperiod treatment as compared to long-day photoperiod treatments), and node number of first flowering under short and long-day photoperiods was detected. Four accessions were classified as photoperiod-insensitive, 49 as intermediate response, and 47 as highly photoperiod-sensitive based on their flowering response to photoperiod. A significant (r = 0.92, P ≤ 0.0001) positive correlation was observed between days to flowering under short-days and photoperiod sensitivity. In photoperiod-insensitive accessions fewer degree days were required for flowering as compared to intermediate and highly photoperiod sensitive ones. Under long-day photoperiod, the photo-thermal and thermal units required to initiate flowering accumulate faster. Thus photoperiod-insensitive accessions required fewer accumulated thermal and photo-thermal units.