A VERNALIZATION MODEL IN ONION (Allium cepa L.)

Abstract

Vernalization is a process required for certain plant species, among them onion (Allium cepa L.), to enter the reproductive stage, through an exposure to low, non-freezing temperatures. Currently, there is a lack of a realistic vernalization model in onion, which provides a rationale for this effort. The objective of this study was to develop a vernalization model that describes the response of development to vernalizing temperatures and to the duration of the vernalization period in onion. The temperature response of vernalization was described by a nonlinear beta function that has three coefficients (the cardinal temperatures), which were defined as 0, 10, and 16°C. The response to the duration of the vernalization period was described by a nonlinear MMF function with four coefficients (the response of unvernalized plants, the response of fully vernalized plants, the duration of the vernalization treatment when plants  are half fully vernalized and a shape coefficient), which were defined as 0, 1, 30 vernalization days, and 5, respectively. The vernalization model successfully described the response of development to vernalizing temperatures and to the duration of the vernalization period of several American, European, Japanese, and Brazilian onion cultivars published in the literature, which were independent data sets.