Mitigation of drought stress effect on growth and productivity of mung bean by foliar application of sorghum water extract

Abstract

Field trial was conducted in Research Field equipped with rainfall transparent
shade, Biology Department, College of Science, Baghdad University during the
growing season of 2012 to test the potential of sorghum water extract in improving
yield and yield components of local cultivar of mung bean crop grown under
different moisture deficit stresses. The water stresses were applied by irrigated the
plots to field capacity and withheld the next irrigation until the soil water deficit
reaches 80, 50 and 30% of field capacity for control, mild water stress and higher
water stress, respectively. Foliar application of sorghum water extract at 0 ( control),
2.5 and 5% (W/V) was made at preflowering, flowering and fruiting stages. The
experiment was conducted in split plot design with four replications for each
treatment. The sorghum water extract rates were kept in the sub plot while moisture
deficits were assigned as main plot.
Results showed that drought stress significantly reduced the averages seed
yield , dry matter accumulation, number of pods per plant, number of seeds per pod
and plant height. Foliar applications of sorghum extracts significantly increased
seeds yield, dry weight biomass, number of seeds per pod and plant height. The
interaction of drought stress and sorghum water extract treatment significantly
affected seed yield , dry matter accumulation, number of pods per plant, total
chlorophyll content and plant height. Application of sorghum water extract under
severe moisture deficit stress (i.e., 70% field capacity) increased seed yield, dry
weight biomass and plant height , number of pods per plant, number of seeds per
pod by 37.8%, 48.9%,64.3%,8.7% and 5.1%, of control, respectively compared the
reduction achieved by the sever moisture deficit applied alone which was 58.50% ,
56.06% , 57.17% , 48.05% and 14.78 % of control for the aforementioned
parameters respectively.
Chlorophyll content was found to be increased by effected by application of
sorghum extracts at control moisture treatment. Proline content of leaves was
significantly increased by high drought stress when water extract applied alone.
However, such differences disappeared when sorghum extract was applied,
suggesting another mechanisms could be responsible for the stimulatory effect of
sorghum extract under drought stress.