Ripening dynamics and natural falling of spring rape seeds
2005
Spokas, L. (Lithuanian University of Agriculture, Akademija, Kaunas distr. (Lithuania)), E-mail: [email protected] | Velicka, R. (Lithuanian University of Agriculture, Akademija, Kaunas distr. (Lithuania)), E-mail: [email protected] | Rimkeviciene, M. (Lithuanian University of Agriculture, Akademija, Kaunas distr. (Lithuania)) | Marcinkeviciene, A. (Lithuanian University of Agriculture, Akademija, Kaunas distr. (Lithuania))
In the period 1997-1999 and 2001, at the Experimental Station of the Lithuanian University of Agriculture the ripening dynamics, natural seed falling from pods and the dynamics of seed quality variation of common and hybrid spring rape (Brassica napus L. ssp. oleifera annua Metzg.) varieties were investigated. These parameters determine the beginning and duration of rape harvesting. Analysis of the biometrical indexes allowed to state that while harvesting common rape varieties the stubble should be left 0.3 m and while harvesting hybrid rape varieties ('Terra') 0.5 m high. The yield of seeds was highest for the common rape variety 'Sponsor' (2.98 t ha-1) and hybrid rape variety 'Terra' (3.35 t ha-1). The biggest mass of 1000 seeds was shown by the rape variety 'Lisora' (3.58 g). Data on the rape ripening dynamics show that under favourable meteorological conditions direct rape harvesting with a combine should be started when the humidity of seeds is less than 15%. Under unfavourable meteorological conditions rape harvesting should be started when the humidity of seeds is less than 20%. The duration of rape harvesting is influenced by natural losses of seed falling, its permissible limit being 1%. The harvesting duration of the rape varieties 'Lisora' and 'Ma-rinka' should be 2 days, because the wet daily losses of seeds are 0.7%. The duration of harvesting of the rape varieties 'Sponsor' and 'Terra' is 6 days. Daily seed loss in the rape variety 'Sponsor' are 0.07% and 'Terra' 0.05%. Results of the investigation of seed quality variation show that a delayed harvesting of common and hybrid rape varieties decreases the content of raw fats in the seeds by 3% and increases that of glucosinolates by 4%. The content of raw fats in the seeds of the hybrid rape variety 'Terra' decreased by 0.6%
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