Identification of variability in phenological responses in canola-quality Brassica juncea for utilisation in Australian breeding programs

Abstract

Canola-quality Brassica juncea is a potential alternative crop species in lower rainfall Australian environments due to its superior heat and drought tolerance, disease resistance, and pod-shatter resistance compared with the currently grown B. napus species. Canola-quality types of B. juncea that are adapted to flower and mature before water deficits and high temperatures significantly limit yield potential are currently being developed. In this study, the variability in phenological characteristics in canola-quality B. juncea is assessed, with a view to identifying the potential for including a range of genetic phenological controls on the development of the crop to assist with adaptation. Vernalisation response was compared among 17 lines of B. juncea and 3 of B. napus, using a cold treatment of 2.6°C for 25 days. Leaf number, and duration to first flower and maturity were compared in response to the vernalisation treatments. To assess day length response, the same 20 genotypes were sown at five locations with a range of sowing times, and one controlled environment, where day length was artificially extended. Development stages were assessed and the duration of particular phenological phases determined in relation to time, thermal time, and photoperiod. The major factor controlling flowering in canola-quality B. juncea genotypes was day length, with only small responses to vernalisation detected. There was sufficient variability in these traits and in thermal time to flowering under long days (intrinsic earliness) within the current canola-quality germplasm in Australia to select early flowering genotypes with potential adaptation to low-rainfall environments.

Filocrono e número de folhas da canola em diferentes condições ambientais

“…A redução no número de folhas com o atraso da semeadura, sob fotoperíodo longo e baixas temperatura do ar, também foi observada por Nanda et al (1995). O aumento do fotoperíodo induz o florescimento e causa redução na TEF (Nanda et al, 1996) (Burton et al, 2008). O efeito do fotoperíodo em B. juncea foi maior do que nos demais genótipos, o que está de acordo com a sua maior sensibilidade a esta variável ambiental (Burton et al, 2008).…”

“…O aumento do fotoperíodo induz o florescimento e causa redução na TEF (Nanda et al, 1996) (Burton et al, 2008). O efeito do fotoperíodo em B. juncea foi maior do que nos demais genótipos, o que está de acordo com a sua maior sensibilidade a esta variável ambiental (Burton et al, 2008).…”

“…No entanto, de forma similar à observada para o filocrono do caule, a semeadura tardia também aumentou o filocrono do ramo. É provável que a emissão de ramos, com o aumento do fotoperíodo, tenha sido responsável pelo aumento no filocrono, uma vez que ela influencia significativamente o crescimento e desenvolvimento da canola, conforme Burton et al (2008) e Gomez & Miralles, (2011).…”

Phenotypic variation of life‐history traits in native, invasive, and landrace populations of Brassica tournefortii

“…But while rapid reproductive phenology is critical for this plant to succeed in its North American range, the crop fields of landrace populations may have led to slower reproductive phenology. In Brassica used for canola, increasing day length and warmer temperature is important for development of inflorescences (Burton et al, ). Most importantly, the length of the reproductive period is an evolutionary response of many desert annuals to cope with aridity (Kemp, ).…”

Yield response of canola (Brassica napus L.) to different inter-row spacings and sowing dates in northwest of Paran, Brazil

“…Yan and Holland (2010) pointed out that the expression of crop yield potential depends on the genetic and environmental components and on the interaction between them. Therefore, as stated in Burton et al (2008), an indeep understanding of the phenological and physiological factors able to cause genotype-environment interaction could help growers to optimize grain yield and quality. In this context, the aim of this research was to evaluate the grain yield response and the oil content of four canola hybrids submitted to different sowing dates and inter-row spacings in the state of Parana Northwest area.…”