Growth analysis of spring-type oilseed rape

Abstract

Abstract A quantitative analysis of growth, development and yield of eight genotypes of Brassica napus L. and two genotypes of B. campestris L. were conducted in 1980 field experiments in central Alberta. B. campestris L. reached all growth stages, except onset of stem elongation, earlier than B. napus L. and correspondingly had a shorter stem elongation period and seed formation period. B. campestris L. had higher leaf emergence rates during all growth periods. B. napus L. had greater crop dry weight at first flower and fifteen days after first flower and greater mean crop growth rate from seeding to first flower. Mean relative growth rates were higher in B. napus L. than B. campestris L. during all growth periods. B. napus L. had greater leaf area index at first flower and fifteen days after first flower, greater axillary branch leaf area index at first flower, greater leaf area duration from first flower to maturity of first pod, and greater axillary branch leaf area duration from first flower to maturity of first pod,than B. campestris L. Late maturing genotypes of B. napus L. had higher leaf emergence rates during all growth periods than did the earlier maturing genotypes, but were later in reaching first axillary branch leaf, first flower, first true leaf senesced and end of true leaves. This study confirmed other studies which indicated ‘number of days to first flower’ as a major factor in determining the time to maturity in both annual rapeseed species. Earlier maturing genotypes of B. napus L. had greater mean leaf area ratios from seeding to first flower, axillary branch leaf area duration, and mean relative growth rates over all growth periods. Late maturing genotypes had greater mean unit leaf rate from seeding to first flower, crop dry weight at first flower and fifteen days after first flower, mean crop growth rates over all growth periods and greater leaf area index at first flower and fifteen days after first flower. The greater axillary branch leaf area duration of earlier maturing genotypes of B. napus L. is advantageous since it coincides with seed filling. The usefulness of mean relative growth rate as a selection tool in breeding programs warrants further study. Given the greater efficiency of earlier maturing genotypes, they could be more productive at higher seeding rates than genotypes which are not as efficient.