PHENOLOGY, SEED YIELD AND SEED QUALITY OF COLD TOLERANT SORGHUM RESTORER LINES

Abstract

The sorghum, Sorghum bicolor (L.) Moench, breeding program focused on developing cold tolerant hybrids and carried out at the Colegio de Postgraduados, has new restorer lines. In these lines, it is necessary to evaluate ways to modify their flowering date, as well as to determine their grain yield and seed quality for a future seed production program, in which those lines could be involved. Therefore, three experiments were established under irrigation, combining three lines and three pre-sowing soaking periods (0, 8, and 16 h) (Experiment 1); three lines and three N rates (0, 100, and 200 kg ha-1) applied to the soil (Experiment 2); and three lines with five growth regulator doses (0, 2, and 4 L of Gapol; 1 and 2 L of Pix, per hectare) applied to leaves (Experiment 3). In addition, in each experiment, treatments were combined with two foliar doses of N (0, and 40 or 50 kg ha-1) applied after flowering. None of the treatments modified days to flower for more than two days. Nevertheless, seed yield average of the intermediate and late lines was close to 7.5 t ha-1 with good plant height, panicle exsertion and panicle length. The most frequent seed size was larger than 3.5 mm, in all the lines.