Tese
Milho crioulo e melhorado: tolerância a deficiência hídrica na perspectiva da segurança e soberania alimentar
Fecha
2018-05-25Autor
Langner, Josana Andreia
Institución
Resumen
The objectives of this thesis were to (i) discuss the importance of maize crop
nowadays and its crucial role in the future for food production in scenarios of water defcit,
and its importance in the conservation of landrace cultivars, which hold a considerable part of
this reserve of genetic variability and (ii) to compare the tolerance to water defcit of improved
and landrace, maize cultivars in the field and in rain exclused environment and to determine
FATS threshold in the reproductive period. Information from the temperature shows that in
several places, with the aid of the Genetic Improvement, the characteristic of plants that lead
to drought tolerance were established. It is concluded that for a cultivar to be accepted by the
farmers, in addition to the adaptation characteristics, it must have a high grain yield and
information needs to be disclosed. To quantify the tolerance of local cultivars, field
experiments were conducted in the 2015/2016, 2016/2017 and 2016/2017, 2017/2018
growing season for FTSW in the experimental area of the Plant Science Department at
UFSM, Santa Maria, RS. The landraces cultivars presented similar yield in the irrigated and
non irrigated system, while the improved cultivars increased yield in the irrigated. For FTSW,
'AS 1573PRO' and 'Cinquentinha' presented similar values in the first year, and 'Bico de ouro'
was smaller. In the second year 'AS 1573PRO' presented FTSW, followed by 'Cinquentinha'
and again smaller 'Bico de ouro'. The cultivar 'AS 1573PRO' had the highest tolerance
indicated by FTSW, in a short period of deficiency. The 'Cinquentinha' showed a smaller
tolerance for FTSW, but as indicated by gas exchange measurements under conditions with
prolonged water stress, it is more tolerant, producing ears with grains even under extreme
conditions of water deficit in the FATS experiment.