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Genotype by environment interaction for radiation use efficiency in grain sorghum

G.L. Hammer1, R.L. Vanderlip2, and L.J. Wade3

1 Qld. Dept. Prim. Ind., GPO Box 46, Brisbane, Qld. 4001
2
Dept. of Agronomy, Kansas State Univ., Manhattan, KS 66506, USA
3
Qld. Dept. Prim. Ind., PO Box 81, Emerald, Qld. 4720

Sorghum hybrid ATx623/RTx430 was found to yield more than hybrid Texas 610SR in high yielding environments, but the two hybrids yielded similarly in low yielding environments (1). In this paper we report glasshouse studies on radiation use efficiency (RUE) which may explain some aspects of the observed yield differences between these two hybrids.

Methods

Plants of hybrids ATx623/RTx430 and Texas 610SR were grown in pots in two temperature-controlled glasshouses (17 and 25C). Plants were well watered and fertilized. Pots were arranged in plots to simulate a plant stand. Total biomass produced and photosynthetically active radiation (PAR) intercepted were measured over the four week period prior to anthesis and RUE calculated as their ratio. Further details have been presented elsewhere (2).

Results and discussion

Hybrid ATx623/RTx43O produced more total biomass and produced it more efficiently than hybrid Texas 61OSR, but only at high temperature (Table 1). The physiological basis of the greater RUE of ATx623/RTx430 is unclear. It could have been caused by an improved photosynthesis-respiration balance and/or better distribution of radiation through the canopy. This is considered further in a companion paper (3).

Table 1. Mean values of total dry matter (TOTDM; g m-2) and RUE (g MJ -1 ) for temperature and hybrid treatments

1 Values in each column followed by the same letter do not differ significantly (0.05)

Higher RUE would generate greater biomass and hence, possibly higher grain yield, in favourable environments where light was the main limiting factor. Most field environments for sorghum production in Australia experience temperatures at or above 25C, so higher RUE for ATx623/RTx430

1. Wade, L.J. et al. 1989. Proc. Aust. Agron. Conf., Perth

2. Hammer, G.L. and Vanderlip, R.L. 1989. Crop Sci. 29:370-376.

3. Hubick, K.T. et al. 1989. Proc. Aust. Agron. Conf., Perth

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