Avaliação de genótipos de girassol sob irrigação nas condições do semiárido

Abstract

The experiment was carried out at agriculture section of the Instituto Federal de Educação, Ciência and Tecnologia Baiano - Campus Guanambi and in the laboratories of Technology of seeds at Universidade Estadual de Montes Claros (UNIMONTES) Campus Janaúba, and Forage and Pastures of the Universidade Estadual do Sudoeste da Bahia (UESB) - Campus Itapetinga. It was aimed to evaluate the yield potential (seed number for plant, seed number for lineal meter, total green weigh, total dry weight, stem and leaf green weigh, stem and leaf dry weight and seed yield), the agronomic parameters (initial flowering, plants height, head height, stem diameter, head diameter and stem curvature) and the bromatological composition (dry matter, ash, crude protein, ethereal extract, neutral detergent fiber, acid detergent fiber, cellulose, hemicellulose and lignin) of nine sunflower genotypes, coming of evaluation essays accomplished by the Empresa de Pesquisa Agropecuária de Minas Gerais (EPAMIG). The sowing was in May 13, 2008 and the harvest at 110 days after the planting. The experiment was carried out in semi-arid conditions under center pivot irrigation. The design was in blocks at random with three repetitions in factorial scheme (2x9) being two spacings (70 and 90 cm) and nine genotypes. The genotypes presented, under spacing of 70 cm between rows, larger yield of dry matter (16,6 t ha-1), stem and leaf green matter (16,6 t ha-1), stem and leaf dry matter (6.1 t ha-1) and seeds (3,3 t ha-1). The genotype Hélio 250 produced the largest amount of seeds for plant (1.235 un). When cultivated under spacing of 70 cm between rows, the genotype Catissol 4 presented the best dry matter content (41,4%). However differences (P>0 ,05) were not observed for the dry matter production by the genotypes Aguará 3 (50,3%), Aguará 4 (48,3%), Charrua (51,5%), Hélio 250 (55,7%), Hélio 251 (52,9%) and Hélio 360 (42,7%) under spacing of 90 cm between rows. Ash contents (10,3%), protein crude (11,9%) ethereal extract (18,9%), acid detergent fiber (38,3%), lignin (10,9%) and cellulose (27,5%) were observed. The genotypes showed the best hemicelulose content (12,2%) under spacing of 70 cm, although this spacing has provided increase of the dry matter contents and neutral detergent fiber. It is possible to conclude that the appraised genotypes represent one more alternative forage for the semi-arid due to their agronomic, yield and bromatological characteristics.