Radiation use efficiency of modern and old oat cultivars in Finland

Abstract

Finnish plant breeding of oats has focused on improving stability as well as productivity in northern growing conditions. Breeding for short stature and early maturing oat lines has increased harvest index (HI) close to 55% (Peltonen- Sainio 1991) and grain yields by 0.3% year-1 (Slafer & Peltonen Sainio 2001). However to further increase grain yield, the biomass production should still be augment (Peltonen-Sainio 1991). Since radiation use efficiency (RUE) and accumulated intercepted radiation (.Ri) are major elements of crop growth and biomass production (Gallagher and Biscoe 1978), the aim of this study was to identify how they have changed by plant breeding in northern growing conditions. On growing seasons 2002 and 2003 the crop radiation interception was calculated from spot measurements of incident and transmitted radiation. Above ground dry matter was determined at particular stages of development of the cultivars and green leaf area was measured at the same time. The plots were fertilised with 90 kg and 0 kg N ha-1. Irrigation was practised in 2002. RUE, .Ri, light extinction coefficient k, green leaf area and biomass accumulation were calculated for each cultivar for pre-anthesis. There was no significant difference between the cultivars on biomass accumulation, radiation accumulation or on RUE (P = 0.08) on vegetative period. More total biomass seemed to accumulate on old cultivar even though the difference was not significant. There were also no significant difference between the cultivars on light interception or on light extinction coefficient. Only the 0 kg N ha-1 fertilizer rate resulted in some reduction in light interception during the year 2002. The RUE values at pre-anthesis were higher during the growing season 2002 than on 2003, (means were 2.02 g MJ-1 and 1.78 g MJ-1). The fertilizer rate of 90 kg N ha-1 resulted in higher RUE values than 0 kg N ha-1 on both years. Gallagher, J. and Biscoe, P. 1978. Journal of Agricultural Science 91: 47-60; Peltonen-Sainio, P. 1991. Journal of Agronomy & Crop Science 166: 90-95; Slafer, G. & Peltonen-Sainio, P. 2001. Agricultural and Food Science in Finland 10: 121-131.