THE EFFECT OF AGRONOMIC AND CLIMATIC FACTORS ON WINTER OILSEED RAPE (BRASSICA NAPUS L.) ROOT NECK GROWTH IN AUTUMN

Abstract

The aim of this study was to investigate the growth habit of winter oilseed rape root neck during the vegetative period in autumn. Such information is important for better understanding of winter oilseed rape growth pattern at early stages of development with the purpose to improve over winter survival. Field trials were conducted on Endocalcari – Epihypogleyic Cambisols. For the determination of changes of winter oilseed rape root neck thickness during autumnal development the effect of planting date, seedbed nitrogen application, stand population density, number of calendar days after emergence, accumulated by plants growing degree days and interaction among these factors was tested. For the description of the root neck growth pattern Boltzmann’s growth function performing a nonlinear fitting of estimating parameters was used. Results collected in the experiments indicate that the effect of sowing date including accumulated by plants growing degree days and the number of calendar days after emergence showed much greater effect on winter oilseed rape root diameter than seeding rate or pre-plant nitrogen application. On the basis of collected data winter oilseed rape root neck growth model was developed. These studies that relate mentioned factors to fall growth of winter oilseed rape root neck are presented in the paper.

Keywords: growing degree days, number of calendar days, nitrogen application, stand population density.

Article DOI: http://doi.org/10.15544/RD.2015.025