Progress towards flowering of faba bean (Vicia faba L.) is more than photothermal

Abstract

Predicting and understanding the progress towards flowering in faba bean are important to achieve the adaptation and high productivity of the crop under varying environmental conditions. Traditional controlled-environment experiments showed that the rate of progress towards flowering was dependent mainly on photoperiod and temperature. Here, we highlight the need to include measures of solar radiation and water deficit in order to achieve an adequate model for field conditions. The improved model was assessed in two steps: first with a "basic" model across all 20 cultivars and then with an "extended" model that included terms to fit exceptional cultivars. The two new parameters were necessary to achieve an acceptable fit of progress towards flowering and clearly separated two cultivars, "Kontu" and "Witkiem Manita," that were significantly quicker to flower than the other 18, which fit a single line. As the regression coefficients of the two exceptional cultivars differed only in intercept, not slope, we conclude that flowering responses to day length, temperature, solar radiation and drought stresses were consistent in this set of germplasm and that the two cultivars differed in earliness "per se." Growth-chamber experiments added information about differing ceiling temperatures for progress to flowering in four cultivars and different sensitivities to supraoptimal temperatures.

Shortening the generation cycle in faba bean (Vicia faba) by application of cytokinin and cold stress to assist speed breeding

“…The application of exogenous cytokinin may compensate for this reduction. sponse progression needs to be addressed (e.g., Croser et al, 2018;Lizarazo et al, 2017). Combinations of SB protocols involving plant growth regulators and light modification were used to optimize early flowering response that lead to acceleration of generation advance in other pulse crops (Mobini et al, 2015;Mobini & Warkentin, 2016).…”

“…These approaches, combined with results here, may lead to additional reduction in faba bean generation time as part of a reliable speed breeding protocol for this species. Lizarazo et al (2017) showed that progression towards flower development in faba bean was affected not only by photoperiod and temperature but also by abiotic stress and solar radiation. In addition, novel ways of achieving earliness, such as deployment of the terminal-inflorescence mutation (ti), may provide complementary additions to the protocol.…”

“…The next step would be to implement accelerated faba bean development to the flowering stage by employing either cold treatment or plant growth regulators. Better understanding of the potential effects of light quality and quantity in growth chambers and greenhouses on flowering response progression needs to be addressed (e.g., Croser et al., 2018; Lizarazo et al., 2017). Combinations of SB protocols involving plant growth regulators and light modification were used to optimize early flowering response that lead to acceleration of generation advance in other pulse crops (Mobini et al., 2015; Mobini & Warkentin, 2016).…”

Understanding photothermal interactions will help expand production range and increase genetic diversity of lentil (Lens culinarisMedik.)

“…For example, low light quality (Mobini et al, 2016;Yuan et al, 2017) or water stress (Gorim & Vandenberg, 2017) can accelerate flowering, while supraoptimal temperatures will delay and/or prevent flowering (Saint-Clair, 1972;Summerfield et al, 1991). Lizarazo et al (2017) were able to improve their DTF predictions in faba bean with the inclusion of solar radiation and water deficit measures to the photothermal model. In Metaponto, Italy 2017, 126 of the 181 days of the field trial had a daily mean temperature below 15°C and experienced mean temperatures of less than 5°C on the 90-93 rd and 115 th day after sowing (Fig.…”

“…; Ellis et al, 1994a), mung bean (Vigna spp. ; Ellis et al, 1994c) and faba bean (Vicia faba L.; Catt & Paull, 2017;Lizarazo et al, 2017); and has potential utility for predicting days from sowing to flowering and quantifying temperature and photoperiod sensitivity, which could assist breeders in identifying genotypes adapted to a specific environment. In addition, equation 1 can be modified to estimate the 'nominal base temperature'…”