Heat stress effects around flowering on kernel set of temperate and tropical maize hybrids
Final kernel number in the uppermost ear of temperate maize [Zea mays L.] hybrids is smaller than the potential represented by the number of florets differentiated in this ear, and than the number of silks exposed from it [i.e., kernel set less than1]. This trend increases when stressful conditions affect plant growth immediately before [GS1] or during [GS2] silking, but the magnitude of change has not been documented for heat stress effects and hybrids of tropical background. In this work we evaluated mentioned traits in field experiments [Exp1 and Exp2], including [i] two temperature regimes, control and heated during daytime hours [ca. 33-40°C at ear level], [ii] two 15-d periods during GS1 and GS2, and [iii] three hybrids [Te: temperate; Tr: tropical; TeTr: Te x Tr]. We also measured crop anthesis and silking dynamics, silk exposure of individual plants, and the anthesis-silking interval [ASI]. Three sources of kernel loss were identified: decreased floret differentiation, pollination failure, and kernel abortion. Heating affected all surveyed traits, but negative effects on flowering dynamics were larger [i] for anthesis than for silking with the concomitant decrease in ASI, and [ii] for GS1 than for GS2. Heat also caused a decrease in the number of [i] florets only when performed during GS1 [-15.5 percent in Exp1 and -9.1 percent in Exp2], and only among Te and TeTr hybrids, [ii] exposed silks of all GS x Hybrid combinations, and [iii] harvestable kernels [mean of -51.8 percent in GS1 and -74.5 percent in GS2]. Kernel abortion explained 95 percent of the variation in final kernel numbers [P less than 0.001], and negative heat effects were larger on this loss [38.6 percent] than on other losses [less or equal than 11.3 percent]. The tropical genetic background conferred an enhanced capacity for enduring most negative effects of heating.
| Main Authors: | , , , |
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| Format: | Texto biblioteca |
| Language: | eng |
| Subjects: | FLOWERING DYNAMICS, GENOTYPES, HEAT STRESS, KERNEL SET, MAIZE, SILK EXPOSURE DYNAMICS, AGRICULTURAL LAND, FIELD SURVEY, FLOWERING, GENOTYPE, GROWTH RATE, HEAT SHOCK, HEATING, HYBRID, POLLINATION, TROPICAL ENVIRONMENT, ZEA MAYS, |
| Online Access: | http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber=46517 |
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