DETASSELING IN PARENTAL SINGLE CROSSES OF MAIZE (Zea mays L.) HYBRIDS FOR HIGH VALLEYS OF MEXICO

Good quality seed is a crucial input for the increase of maize productivity (Zea mays L.), and must be produced using strict procedures and controls. Technology for the production of hybrid seed is limited and, therefore, the effect of removing the tassel of the female parent (detasseling) was evaluated on seed productivity and quality and the interaction with the environment of simple cross females in hybrids for the High Valleys OF Mexico. Between 2006 and 2008 in Texcoco, Estado de Mexico (2250 masl), 15 treatments were evaluated: five simple crosses (CML-239xCML-242, M-43xM-44, M-47xM-46, CML-241xCML-243, and M-55xM-54) and three levels of detasseling (removing tassel, tassel and flag leaf and tassel not removed) in a randomized complete block design with three repetitions. Differences (p <= 0.01) were found between simple crosses and years, yield and physical quality of seed; there were no significant differences for detasseling. The interaction was significant for the beginning of male flowering and yield. Crosses averaged 70 to 72 d for the start of male and female flowering, with floral synchrony, and two days to begin detasseling and avoid self-pollination; yields were 4.79 to 9.43 t ha(-1), 32 to 78 % for large seeds, and 62 to 68 kg hL(-1) test weight. Removing the tassel increased yield by 6.31 % and reduced the amount of small seed by 10.5 % in comparison to the control. In 2006 there was a difference of 4 d for the start of female flowering and 2 din 2008 in comparison with 2007; in 2008 yield was 9.4 t ha(-1), and in 2006 it was 44.68 % lower. In 2008, M-43xM-44 yielded 11.24 t ha(-1), and in 2006 and 2007, yields were 42.32 and 14.11 % lower. To determine where, when, and how to produce hybrid seeds, one must know the parents, place of production, and interaction.