پديد آورندگان :
جمشيدي، پريسا دانشگاه صنعتي شاهرود - دانشكده كشاورزي - گروه زراعت و اصلاح نباتات , برادران فيروزآبادي، مهدي دانشگاه صنعتي شاهرود - دانشكده كشاورزي - گروه زراعت و اصلاح نباتات , علومي، حكيمه دانشگاه تحصيلات تكميلي صنعتي و فناوري پيشرفته - پژوهشگاه علوم و تكنولوژي پيشرفته و علوم محيطي - گروه اكولوژي , نقوي، هرمزد سازمان تحقيقات، آموزش و ترويج كشاورزي - مركز تحقيقات و آموزش كشاورزي و منابع طبيعي استان كرمان - بخش تحقيقات خاك و آب
چكيده لاتين :
Introduction: In order to evaluate the effect of foliar spraying of zinc and calcium on yield and
physiological traits of safflower under lead stress, a factorial experiment based on randomized complete block
design was performed in Kerman agricultural and natural resource research and education center in 2014-2015
with three replications. The first factorial included three levels (control, and 0.5 and 1 μM lead spraying),
whereas the second and third factorials were spraying zinc sulfate at three concentrations (zero, and 10 and 20
μM) and spraying calcium chloride at two levels (zero and 20 μM), respectively. According to the results, grain
yield, the 1000-grain weight, leaf dry weight, number of seeds per head, head weight and chlorophyll content
decreased. On the other hand, a significant increase was observed in the activities of catalase and ascorbate
peroxidase enzymes and amount of malondialdehyde in plants. Moreover, spraying zinc fertilizer in lead
treatment resulted in a significant increase in activity of catalase enzyme, reduction of membrane lipid
peroxidation, prevention of chlorophyll destruction and maintenance of grain yield. However, the effect of
spraying calcium fertilize in lead treatment was only significant on chlorophyll content. According to the results
of the research, it seems that spraying zinc fertilizer had more effects on improved growth of safflower under
lead stress, compared to spraying calcium fertilizer. Therefore, in air pollution with heavy metals (lead),
application of zinc sulfate fertilizer can be an effective approach to maintain the growth and production of plants.
Among the various heavy metals, lead (Pb) is a major anthropogenic pollutant that has been released to the
environment since the industrial revolution and accumulated in different terrestrial and aquatic ecosystems These
elements will transfer to leaves in polluted areas and will rapidly uptake and cause irreparable damages to the
most important part of the plant, i.e. photosynthetic system and changes immune system activity (Enzyme
activity) and finally reduces the plant yield. Ca2+ improves plant resistance is related to maintaining a higher
photosynthetic rate under stresses. Zn has a role in modulation of free radicals and their related processes
through antioxidant properties and Zn applied by foliar spraying can increase the yield of crops. Therefore, this
study aims to investigate how zinc and calcium fertilizers as foliar application increase safflower plant resistance
to lead stress and their role on the damages caused by the stress on the activity of antioxidant defense system and
photosynthetic pigments and its role in improving the plant yield in lead leaf absorption.
Materials and Methods: The field experiment was carried out in a factorial based on randomized complete
block design with three replications in the farm of Agricultural and Natural Resources Research and Education
center of Kerman. The first factor consisted of three levels of lead (Control, 0.5 and l mM lead foliar) and the
second factor, the foliar application of zinc sulfate in three concentrations (zero, 10 and 20 mM) and the third
factor was the foliar application of calcium chloride in two concentrations (zero and 10 mM). Cultivars used in
this experiment were Goldasht cultivars (safflower). In this study, the activity of ascorbate peroxidase, catalases
enzymes and malondialdehyde contents were measured. At harvest time, stem and leaf dry weight, seed number
per head, Head weight, 1000 seed weight and seed yield was calculated. All data were analyzed with SAS
software. Analysis of variance and statistical analysis was performed using SAS and Excel softwares, Mean
comparison was done by least significant difference (LSD) test at 5 percent.
Results and Discussion: The results indicated that lead stress had a significant effect on most of the studied
traits. Due to lead stress seed yield, 1000 seeds weight, leaf dry weight, seed number per head, head weight and chlorophyll contents decreased and the activity of catalases, ascorbate peroxidase and malondialdehyde contents
showed significant increase in the plant. Based on the results we concluded that, decrease in seed yield and plant
growth by lead exposure can be in relation to this toxicity and oxidative stress. Also the present results revealed
that the increase in the activity of catalases, ascorbate peroxidase and malondialdehyde content prevent the
occurrence of oxidative damage under Pb stress. The results showed that lead and zinc interaction effects were
significant on grain yield, chlorophyll b and malondialdehyde. The foliar application of zinc improved catalases
enzymatic activity, decreased membrane lipid peroxidation and prevented destruction of chlorophyll and
maintained yield in stress lead. The optimization of zinc under Pb stress could alleviate Pb-induced toxic effects
by enhancing biochemical reactions and physiological processes in safflower plant. The variance analysis
showed that only lead and calcium interaction effects on chlorophyll a were significant. Content of chlorophyll a
increased at non-stress conditions along with the foliar treatment of calcium (10 mM) compared to the control.
Conclusions: The lead toxicity led to decline in growth and dry matter accumulation and the reduction of
chlorophyll synthesis in plants and finally the reduction of the safflower yield. In the lead stress condition, the
foliar application of zinc sulfate can be affected in the activation of plant defense systems and prevented the
destruction of chlorophyll. Calcium successfully prevented occurrence of chlorosis and increased chlorophyll
content. Based on the results, it seems that the application of zinc can have a greater impact on improving
safflower growth than calcium fertilizer in lead stress. So in areas contaminated by heavy metals lead, zinc
sulfate fertilizer can be as a solution to keep growing and production plants.
