Germination and Early Seedling Development under Low Temperature in Canola

Abstract

Canola is seeded when ambient temperatures are below the optimum. Therefore, we wished to determine whether certified seedlots displayed variation in low temperature germination potential and, thereafter, to study the effects of low temperature during germination and early seedling development. Canola (Brassiea napus L. cv. Westar) seed was tested for germination potential at 22, 10, 6, and 2 °C. Two seedlots, designated L and H, which represented the extremes in germination potential at 10 °C, were chosen for further study. Under the optimal conditions of 22 °C the two seedlots exhibited similar germination rates and early seedling growth. At 10 °C, L reached 95% germination within 8 d and displayed rapid seedling growth. This was associated with high isocitrate lyase activities and rapid mobilization of total lipid and protein reserves. Seedlot H, at 10 °C, did not reach a high percentage of germination until Day 12, and seedling growth was slow relative to that of L. Seedlot H had more gradual increases in isocitrate lyase activity, mobidization of storage lipid, and protein mobilization at 10 °C. Both seedlots germinated poorly at 6 and 2 °C. At 6 °C, L displayed higher isocitrate lyase activity and higher rates of lipid and protein mobilization than H. From these studies we have determined that low temperature has a deleterious effect on the germination of canola and this may be reflected in a loss or a delay of coordination in the mobilization of reserves. In addition, differences within the Westar cultivar exist with respect to germination under low temperature.

The effect of temperature, seed colour and linolenic acid concentration on germination and seed vigour in flax

“…This conclusion is more in agreement with this study, perhaps because of greater similarity in development stage of the germinated seeds. Lower germination temperatures may prevent or delay the mobilization of seed reserves in germinating seeds, leading to lower germination (Nykiforuk and Johnson-Flanagan 1994).…”

“…Temperature is one of the major environmental factors affecting germination (Nykiforuk and Johnson-Flanagan 1994). According to O'Connor and Gusta (1994), temperature (over a range of 5-15°C) had no significant effect on germination frequency of flax, but seedling emergence was dramatically reduced by temperatures of less than 10°C.…”

Canola as a New Crop for California: A Simulation Study

“…When sowing prior to the middle of October, under rain-fed conditions, it is likely that there will be insufficient soil moisture to support germination in much of the region. After approximately the last week of November low soil temperatures may cause germination and establishment problems in central and northern California (George et al, 2017b;Nykiforuk and Johnson-Flanagan, 1994;Nykiforuk and JohnsonFlanagan, 1999). For these reasons, 15 October was set as the earliest sowing date and 20 November as the latest sowing date.…”

Evaluation de la variabilité de jeunes plants deMedicagosoumis à un régime de basse température

“…Maheswaran et Subramanian ( 1989) montrent, chez le Riz, que les varietes tolerantes ont le taux de survie le plus eleve (plus de 50%) et Ia longueur de Ia jeune plante Ia plus importante (plus de I 0 em). Toujours chez le Riz, Jacquot et al (1992) (Black, 1957;Stebbins, 1976) ne serait pourtant pas une regie absolue lors d'un traitement a basse temperature (Barber et a/., 1991 ;Nykiforuk & Johnson-Flanagan, 1994); -au niveau intraspecifique, les resultats montrent que le bon developpement de Ia jeune plante soumise a un regime de basse temperature est lie a l'origine de chaque population ; en effet, les population Acl 212, Acl 203, Acl 209, Pol 226, Pol 22, Cill3-c et Cil II, toutes originaire des sites de hautes altitudes et a hiver tres froid, montrent une superiorite dans le developpement par rapport aux populations originaires des sites des basses altitudes et a hiver doux ; ces resultats confirment ceux obtenus avec les ecotypes de M. aculeata et M. truncatula (Bounejmate et al, 1993) et d'autres auteurs qui ont conclu que l'origine climatique joue un role important dans la tolerance au froid (Jones & Peterson, 1976 ;Eagles & Hardacre, 1979 ;Eagles & Brooking, 1981 ).…”

“…Les especes annuelles de Medicago n'echappent pas a cette regie et c'est pour cette raison qu'il est indispensable de preconiser des especes ou varietes fourrageres devant presenter une croissance hivernale suffisante pour etre valorisees et une vitesse d'implantation rapide (Prosperi eta!., 1993). La croissance de jeunes plantes sous un regime de basse temperature est souvent utilisee comme crible dans Ia classification et Ia determination de populations et de varietes de differentes especes tolerantes au froid (Hardacre & Eagles, 1980 ;Maheswaran & Subramanian, 1989;Bounejmate eta!., 1993 ;Nykiforuk & Johnson-Flanagan, 1994). Les marqueurs biochimiques tels que les proteines sont egalement utilises pour cribler des plantes resistantes au froid Mohapatra et a!., 1987 ;Kurkela eta!., 1988 ;Guy et a!., 1988 ;Perras & Sarhan, 1989 ;Mohapatra et a!., 1989 ;Ort eta!., 1989 ;Guy & Haskell, 1989 ;Guy, 1990 ;Antikainen & Pihakaski, 1993 …”