Heat stress during late vegetative growth of maize effects on phenology and assessment of optimum temperature
Prediction of phenology is based on thermal time [TT] computation, which requires the correct definition of base [TB] and optimum [TO] temperatures. Most information on these traits came from controlled environments using a wide range of mean air temperatures [TX], including TX greather than TO and TX less than TB. These conditions are rarely found in field environments. We assessed the effect on development of day-time temperatures above TO during late-vegetative growth of maize [Zea mays L], and established a model based on TT computation on a per hour [TTh, in °C h] rather than per day basis [TTd] for TO estimation. Field experiments included two temperature regimes [TC: control; TH: heated] between V11 and tasseling of TC. We registered temperature at ear level, and dates of anthesis and silking. We computed developmental rates [DR], TTh above 8°C during treatment period [TTh1] and between V11 and silking [TTh2], a stress index based on the quotient of differences in TTh [deltaTTh] between TH and TC [SI = deltaTTh2/deltaTTh1], and TO. Heat stress caused a delay in flowering events, and a decline in DRs. Estimated TB was higher [12.7°C] than normally used in computations. Estimated TO was within the expected range [36°C greather thanTO greather than 30°C], independently of TB. Stressful temperatures promoted a delayed in silking, identified as an increase of at least 2.14°C h in TTh for each degree above TO. Estimated TO differed between growing seasons [P = 0.04], suggesting possible variation due to climatic effects.
| Main Authors: | , , |
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| Format: | Texto biblioteca |
| Language: | eng |
| Subjects: | ZEA MAYS, |
| Online Access: | http://ceiba.agro.uba.ar/cgi-bin/koha/opac-detail.pl?biblionumber=46565 |
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