Abstract:
The aim of this experiment was to investigate the responses
caused by progressive water stress and the necessary time for have biochemical
and physiological changes of Vigna unguiculata (L.) Walp. cv: manteguinha
during the vegetative phase. Leaf Relative Water Content (LRWC), Nitrate
Reductase Activity (NRA), free proline, total soluble carbohydrates, free
amino acids and total soluble proteins were quantified. The plants under
the control treatment maintained stable variables; however, those under
water stress suffered an increase of 97.3% in proline due to osmotic adjustment,
increase of 78.4% in free amino acids, caused by the break down of proteins
by protease enzymes, increase in total carbohydrates by 94.2% due to a
decrease in the photosynthetic capacity and low synthesis of sucrose used
for exporting this solute. There was a decrease in 25.7% of the leaf relative
water content in virtue of low water availability in the soil, reduction
of 43.8% in Nitrate Reductase Activity (NRA) due to the regulation of
this enzyme being induced by its substratum and 47.3% of total proteins
due to the paralyzation of protein and proteolytic protein degradation,
being maximized the variations in the parameters evaluated according to
the increase in the period the plants were exposed to water stress. Physiological
changescan be carried out in only a few days. However, biochemical
responses should be evaluated starting at 4 days under water restriction.
A.K.S. Lobato, C.F. Oliveira Neto, R.C.L. Costa, B.G. Santos Filho, F.J.R. Cruz and H.D. Laughinghouse IV, 2008. Biochemical and Physiological Behavior of Vigna unguiculata (L.) Walp. Under Water Stress During the Vegetative Phase. Asian Journal of Plant Sciences, 7: 44-49.
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