Brassica juncea Canola in the Northern Great Plains: Responses to Diverse Environments and Nitrogen Fertilization

Abstract

Brassica juncea var. juncea canola is a new oilseed species that is developed from B juncea (L.) Czern. mustard with its oil and meal quality equivalent to conventional canola species. Understanding of the phenological characteristics and yield responses to diverse environments will allow the crop to be better adapted to target production areas. This study determined the responses of the juncea canola to various soil‐climatic conditions and was compared with B napus L. canola, B rapa L. canola, juncea mustard, and Sinapis alba L. mustard. The five oilseed species/cultivars were grown under various N fertilizer rates (0, 25, 50, 100, 150, 200, and 250 kg N ha−1), at four Saskatchewan locations from 2003 to 2005. On average, flowering began 40 d after seeding (DAS) for alba mustard and rapa canola (earliest), 49 DAS for napus canola (latest), and 44 DAS for juncea canola (intermediate). Flowering duration was longest for juncea canola (30 d) and shortest for napus canola (22 d). The napus canola and juncea mustard produced higher (1684 kg ha−1) seed yields than the three other oilseeds (1303 kg ha−1 on average). For all oilseed species, the seed yield was highly responsive to N fertilizer rates from zero to about 100 kg N ha−1, and thereafter, the rate of yield responses declined. The amount of N fertilizer required to achieve the maximum seed yield was 106 kg N ha−1 for rapa canola, 135 kg N ha−1 for alba mustard and napus canola, and 162 kg N ha−1 for the two juncea spp. Overall, juncea canola had lower seed yield than more popular hybrid napus canola, and the yield stability of juncea canola was lowest among the five oilseed species when examined across diverse environments. Earlier flowering, longer flowering duration, and greater tolerance to drought stress exhibited by juncea canola make the crop best adapted to the drier areas of the northern Great Plains. The improvement of seed yield and yield stability is the key to potentially adapt this new oilseed species to a wider range of environmental conditions.