Carbon dioxide exchange in attached flag leaves and ears of hexaploid triticale in relation to seed shrivelling

Abstract

Abstract Two cultivars of triticale were grown in a controlled environment and carbon dioxide exchange in attached flag leaves and ears was measured using an infrared gas analyzer during 30 days after anthesis. The photosynthetic rates of apparent CO2 uptake for flag leaves of S71–142 and IMJ-3 during most of this period were similar whereas rates for ears of IMJ-3 (a poor kernel type) were higher than for S71–142 (a better kernel type). The mean rate of dark respiration for flag leaves of S71–142 during 28 days of anthesis was 49% higher than for IMJ-3; the mean rate of dark respiration for ears of IMJ-3 was 19% higher than for S71–142 over the entire growing period. The flag leaves of IMJ-3 were 15–20% larger than those of S71–142. Number of grains per ear (sink) in IMJ-3 was not much larger (68 grains per ear as compared with 62 in S71–142) and yet kernel shrivelling was more pronounced in IMJ-3. Therefore, it appeared that source was not a limiting factor and it was not responsible for kernel shrivelling.