Assimilate transport in maize (Zea mays L.) seedlings at vertical low temperature gradients in the root zone
Sowinski, Pawel ; Richner, Walter ; Soldati, Alberto ; Stamp, Peter
In: Journal of Experimental Botany, 1998, vol. 49, no. 321, p. 747-752
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- Even moderate chilling temperatures may cause important modifications in assimilate movement in maize seedlings from the shoot to the roots, but there is no information on long-distance transport of assimilates in plants subjected to vertical gradients of moderately low temperatures in the root zone. Seedlings of a chilling-tolerant (KW1074) and a chilling-sensitive inbred line (CM109) of maize were grown in a system that allowed the maintenance of temperature gradients between the topsoil (0-10 cm) and the subsoil (10-50 cm). After pregrowth at 24°C until the thirdleaf stage, plants were subjected to chilling-stress regimes for 6 d (17/17/17 °C, 17/17/12°C, 12/12/12°C, 12/12/17°C, air/topsoil/subsoil). The time taken for the assimilates to enter the phloem from the second leaf increased at low temperatures for both lines, but to a much greater extent in CM109. Although mainly influenced by air and topsoil temperature, low temperature in the subsoil also affected this trait in CM109. The speed of assimilate transport between the second leaf and the mesocotyl in KW1074 was strongly reduced by cool temperatures in the shoot and topsoil as well as by 12°C in the subsoil in CM109, because the latter line had a larger portion of its root system in the subsoil as compared to KW1074. The portion of assimilates allocated to the root decreased at low temperatures in both lines, but to a greater extent in CM 109, and was controlled mostly by the subsoil temperature. After rewarming, values of all measured parameters of assimilate transport returned to near pregrowth levels within a few days