عنوان مجله
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Iran Agricultural Research
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چکیده
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To investigate the effect of draught stress on water relations, stomatal
density, chlorophyll content and yield of rapeseed, an experiment was done with four
levels of drought stress including L1 (Field Capacity, FC), L2 (70% Available Water
Content, AWC), L3 (50% AWC), and L4 (30% AWC), within three growth stagesincluding
stem elongation (T1), onset of flowering (T2) and silique formation period (T3) at
the University of Maragheh in 2013. The results showed that the lowest relative water
content and leaf water potential were obtained at 30% AWC and silique development
stage. Meanwhile, the highest water use efficiency (WUE) was observed during flower bud
and silique development stages and 70% AWC. Furthermore, the results demonstrated that
stomatal was only influenced by the levels of applied stresses and the highest stomatal
density was recorded in 30% AWC. Implementation of 30% AWC in silique development
stage diminished chlorophylls a, b, and total chlorophyll content to their lowest points so
that compared to field capacity (L1), they decreased about 59, 67 and 62 percent,
respectively. Likewise, the least grain yield belonged to stress application at flower bud
development stage and 30% AWC stress level. Also, the grain yield loss in L4×T3
(30%AWC in silique formation period) treatment in comparison with the L1 (Field
Capacity, FC) was 46.2 percent. Seed protein content was adversely affected by stress level
and any decrease in AWC led to a concomitant decrease in protein content. At the same
time, seeds oil content was influenced by stress application times. Water deficit stress
during flower bud formation had the greatest adverse effect on seeds oil content. Overall, it
was concluded that severe water deficit (30% AWC) led to the decrease of chlorophylls a,
b, total chlorophyll, seed protein, oil content and yield.
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