Abstract:
Drought is one of the most important stress factors in sunflower
growing. Although sunflower is a well-adapted species to drought, due to its
efficient root system, the negative effects of the climatic stress are shown by
low growing rate, morpho-anatomical, physiological and biochemical
troubles, which result in diminishing the crop yield. The paper presented the
results of primary bio-synthetic processes that have differentiated five
sunflower hybrids (P.I 2001, Select, P.I.2002 ,P.I.2004 and Performer),
cultivated at the Agricultural Research and Development Station of Podu
Iloaiei, by cytological, biochemical and physiological determinations,
according to sowing period, under climatic conditions of year 2007. The
special weather conditions of year 2007 have been studied by determining
the average monthly values of temperature and rainfall, correlated to
quantitative and qualitative values of the yield. The biochemical and
physiological determinations concerned the aspects of water regime and
photosynthesis process. The determination of the rate of leaf dehydration
may be an indicator of the intensity in the transpiration process; water
content and forms from leaves and stems may estimate the activity of
assimilates transportation, and the content of leaf pigments may be
correlated to the intensity of photosynthetic activity of studied hybrids. The
indicators of water regime have been analysed by gravimetric methods
carried out at the current balance, and the content of photosynthetic
pigments was analysed spectro-photometrically and assessed through light
adsorption capacity by acetone extract in red (663 nm) and blue (432 and
453 nm) areas of visible spectrum, typical of the main components of
photosynthetic systems.
