Triazole priming of maize seed to enhance drought tolerance during field establishment - Mexico, DF (Mexico) CIMMYT : 1997 - Printed
Lowland tropical maize environments are often characterized by unreliable rainfall distribution at planting time. Triazoles are plant growth regulators which moderate the effects of drought and high temperatures. We evaluated the triazole 'Paclobutrazol' as a seed primer on two maize cultivars in 1994 and on five maize cultivars in 1995 infield trials conducted at Tlaltizapan, Morelos and at Cocula, Guerrero, and in greenhouse studies at the University of Guelph. In 1994, seeds of hybrids 'P 3288' and 'NK TB 8101 ' were primed with Paclobutrazol 50 alone and in combination with Ancymidol 25 and grown under severe and moderate drought stress in the dry winter season. Compared with the non-primed check at Tlaltizapan, the triazole treatments delayed seedling emergence by 2.4-3.2 days, reduced plant height by 4%, delayed anthesis by 1.4-2.0 days and reduced grain yield by 11-17% across both drought treatments. At Cocula results were similar, though yield differences were non-significant due to a high coefficient of variation. In 1995, five cultivars ('CML8 x CML9', 'CML19 x CML27', 'La Posta Sequia C3', 'SIWA' and 'SIBA') (the last there from ClMMYT's drought breeding program), were seed treated with Paclobutrazol 80 imbibed, Paclobutrazol 20 seed coated, and in combination. The two field trials at Tlaltizapan involved a seedling survival trial with a gradation in levels of irrigation during the establishment phase and a mid-season drought stress trial. The seed coated treatment showed no significant response in either trial; the imbibing treatment reduced surviving seedling counts by 15-21% under severe water stress, slowed the rate of emergence, and resulted in non-significant reductions in biomass and grain yield. In greenhouse experiments at Guelph on the same genotypes and seed treatments, the Paclobutrazol imbibing treatment delayed emergence and reduced seedling height and fresh weight by 30% and 25% respectively, and gave inconclusive results under heat and drought stress. No differences were noted between the seed coated treatment and the check. We conclude that Paclobutrazol cannot be recommended at this stage as an imbibed seed treatment for tropical field maize.
633.153 / EDM