Paper

Question 1

Abstract

Answer 1

1. Early maturity in spring wheat is an important breeding objective in western Canada.
2. Growth and developmental phases (tillering, stem elongation, ear emergence, anthesis and ripening) of wheat are controlled by vernalization and photoperiod response, and earliness per se genes.
3. These genes, along with their interaction with growth temperatures, have a significant role in wheat’s adaptation and yield potential in a diverse range of environments.
4. Vernalization and photoperiod affect floral initiation time, leaf number, timing of other growth stages up to emergence of flag leaf, and tiller numbers.
5. Research into the genes controlling maturity, in response to cold treatment and day length, as well as those determining earliness per se, may aid in the development of wheat cultivars adapted to the various agro-ecological maturity niches of western Canada.

Question 2

Objectives

Answer 2

1. To determine which of the three genetic factors (vernalization, photoperiod, and earliness per se) cause maturity differences in Canadian wheat cultivars.
2. To study the effect of photoperiod and vernalization on important agronomic traits in Canadian wheat cultivars.

Question 3

Materials and Methods.

Answer 3

Plant Material: AC Taber (late), AC Foremost (medium),
Cutler (early), AC Barrie (late), and AC Intrepid (early).

Photoperiod treatments: 16 and 10 hours

Vernalization treatments: 0 and 6 weeks (sprouted seeds vernalized at 1oC in the dark).

Question 4

Results.

Answer 4

The main effect of photoperiod was significant for the number of days to anthesis, while the interaction between photoperiod and vernalization was significant for all the traits studied except number of tillers per plant.

Shorter photoperiod significantly increased days to anthesis in all cultivars, with AC Barrie exhibiting the maximum response (Fig. 1).

Shorter photoperiod also significantly affected FLN in AC Barrie (Fig. 2) and main culm height in AC Intrepid.

AC Taber and AC Foremost exhibited response to vernalization. Vernalization significantly affected FLN and days to anthesis in both these cultivars, and number of spikelets in AC Taber (Figs. 1,2, and 3).

AC Barrie, AC Intrepid and Cutler did not respond to vernalization for any of the traits studied. When vernalized and grown under long photoperiods, only AC Barrie differed significantly from the other cultivars for days to anthesis (Fig. 4). Under similar conditions, of all pair-wise comparisons, only the one between Cutler and AC Foremost showed significant difference for number of spikelets on the main culm.

Question 5

Conclusions.

Answer 5

1. The present study demonstrated the existence of vernalization response in AC Foremost and AC Taber, thereby suggesting the presence of different vernalization genes in these two cultivars.
2. No difference in the earliness per se of AC Taber, AC Foremost, AC Intrepid and Cutler was found, suggesting the late flowering of the former two under field conditions is due to the non- fulfillment of vernalization requirements.
3. Earliness per se was found to be the major determinant of flowering time in AC Barrie, AC Intrepid and Cutler under field conditions.
4. Shorter photoperiod increased FLN in AC Barrie, while vernalization decreased FLN in AC Foremost and AC Taber and number of spikelets in AC Taber.
5. The flowering time in Canadian spring wheats is modified by both vernalization and earliness per se genes.