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| Author(s): |
Beatriz Ibet Lozada Garcia
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 1993-12-17 |
| Advisor: | Luiz Roberto Angelocci |
| Abstract | |
The base data of phenological observations and production was analysed for a corn hybrid essay at Santa Cruz das Palmeiras, objective was S.P, to Brazil, envolving planting dates.The estimate the influence of physical environmental variables on the sub-period duration and the production of corn. The effects of mean air temperature, water excess and deficit calculated from soil water balance dÚring the sub-period planting to flowering, flowering to harvesting and the planting to harvesting cycle, and with the production of the hibrid AG-106 were studied through a regression model. The water balance was calculated acording with Thornthwaite & Mather model, modified with respect to soil water storage and crop coefficient (Kc), for five day periods, was used a changing available soil water content through of the total cycle. The potential evapotranspiration was estimated by Thornthwaite's method. The mean air temperature best explained the length of the sub-period planting - flowering, but the sub-period of flowering to harvesting and the planting harvesting cycle showed low correlation with the analysed variables.The use of degrees-day corrected by a factor which considered the soil water availability improved the planting - flowering duration. The duration of the sub-period was best estimated for a base-temperature of 10°C and when the correction factor for hydric effect was used. The grain yield was best explained by the mean air temperature of the sub-period flowering to harvesting. No a linear correlation was found between grain yield and soil water deficits in all the periods, but an analysis of the relative evapotranspiration deficit effect on the yield, by the model proposed by Stewart (1973), showed a tendency to decrease the maximum yield in about 30% when the mean temperature in the flowering - harvesting sub-period was above 22° C. Below this value, the mean air temperature in this sub-period was the main factor affecting the yield, indicanding a 50% decrease in relation to the estimated yield by Stewart's model. (AU) | |