Phasic development in field crops III. The pseudocereals, buckwheat and grain amaranth

• Published in: Field crops research 1982, Vol.5 (4), p.305-318
• Main Authors: Angus, J.F., Mackenzie, D.H., Myers, R.J.K., Foale, M.A.
• Format: Article
• Language: English
• Subjects: plant ecology
• ISSN: 0378-4290; 1872-6852
• DOI: 10.1016/0378-4290(82)90033-8

The phasic development of a day-neutral cultivar of buckwheat and a short-day cultivar of grain amaranth were simulated using a model adapted from the long-day model described in Part II of this series. The model was fitted to data from serial sowings of both crops at Gatton in eastern Australia. Temperature has a non-linear effect on rate of development of both buckwheat and grain amaranth, and photoperiod has a non-linear effect on rate of amaranth development prior to anthesis. The estimated values of model parameters for buckwheat indicate that its rate of development both before and after anthesis responds with diminishing returns to temperature above a threshold of about 10°C. Above mean daily temperatures of 20°C, the rate of development is effectively constant and crop duration is about 60 days. In the case of grain amaranth the model indicates a threshold temperature of about 10°C throughout the life cycle, and before anthesis it shows a strong short-day response with a critical photoperiod of about 14 h. After anthesis there is no sensitivity to photoperiod. At a temperature of about 20°C and a photoperiod of about 12 h the crop duration is as short as 67 days. Yield and biomass of the little-researched grain amaranth crop were measured over five summer months. The highest seed yield (2.15 t/ha) was for a fast-maturing autumn-sown crop but both yield and growth rate were found to be lower than other C4 species grown at the same time. The adaptation of these pseudocereals in cropping systems is discussed in relation to the potentially short life cycles.