Growth and development of channel millet (Echinochloa turneriana) in relation to its potential as a crop plant and compared with other Echinochloa millets, rice and wheat

Abstract

Abstract The effects of a range of temperature regimes (from 15/10 to 36/31°C), irradiances and daylenghts on the growth and development of Channel millet (Echinochloa turneriana (Domin) J.M. Black) were examined in the Canberra phytotron. The responses were compared with those of the domesticated barnyard millets (Echinochloa utilis and E. frumentacea) as well as with indica and japonica rice cultivars and with wheat. Growth and development of Channel millet can be extremely rapid, with a relative growth rate (RGR) of up to 49% per day and anthesis within 5 weeks of germination, but in these respects E. turneriana was not very different from the already domesticated species of Echinochloa, except that its flowering was less delayed by long days. CO2 exchange rates per unit leaf area (CER) and inflorescence structure were also similar, but kernel size and harvest index were greater in the cultivated millets. No compelling physiological reason was found for the domestication of Channel millet vis-a-vis other millets. The greatest difference between E. utilis and E. frumentacea was in the ability of the more temperately-adapted E. utilis to grow at cool temperatures, at which E. turneriana was intermediate. The japonica and indica rice cultivars differed in parallel with the Japanese and Indian millets. In the three millets and two rices, when grown below 21/16°C, the low RGRs were matched by low “sadpated” CER, but short tern CERs were much higher than ‘adapted’ rates at cool temperatures. At higher temperatures CER approached a plateau above 24/19°C in both rice and millet, whereas in the latter RGR increased progressively up to 36/31°C. In wheat both RGR and CER were relatively unresponsive to temperature. Across all species and temperatures, RGR was much more closely related to relative leaf area growth rate (r = 0.98) and to leaf appearance rate (r = 0.94) than to CER. It is concluded that while CER sets a limit to growth rates, the differences in RGR between species and across conditions were more closely associated with the rate of leaf expansion and the extent to which leaf appearance and expansion were limited by temperature and irradiance.