Effect of sowing date on the behavior of two genotypes of sunflower. II. Nutritional aspects

Abstract

The present experiment was conducted in Ja6oticabal, SP, Brazil, with the objetive of evaluating the behavior of two genotypes of sunflower (Helianthus annuus L.) with respect to nutritional state and nutrient and oil content. The contissol 812 hybrid and the IAC-Anhandi cultivar with 80 cm between lines and tive plants per linear meter were used in randominzed blocks with four replicates in five sowing dates: January 1^st, February 20, March 5, March 20 and April 4. The delay of the sowing date exercised a significant depre5sive effect on the mean values in kg/ha of the nutrient content (N-total = 86,4 and 19,1; P = 8,3 and 1,6; K = 77,0 and 17,5; Ca =52,1 e 6,8 and Mg = 10,3 e 1,7) and nutrient exportation (N-total = 89,6 and 27,3; P = 9,1 and 2,5; K = 30,1 and 8,8; Ca = 7,0 and 2.1 and Mg =9,7 and 2,8) for the first and last dates of the two genotypes which maintened constant (40%) oil content. It is concluded that the two genotypes did not react in different manners and that the sowings realized until the end of February were the best since those realized later were affected negatively, as demonstrated by the reduced total absorption (kg/ha) of she different nutrients due to the reduction of achene production to undesirable levels.