كليدواژه :
اسفناج , توده بومي , كادميم , رشد , فلزات سنگين
چكيده فارسي :
اسفناج از سبزي هاي تجمع دهنده كادميم است، اما پاسخ ژنوتيپ هاي مختلف اين گياه به كادميم مشخص نيست. در اين آزمايش اثر غلظت هاي 0، 30 و 60 ميلي گرم كادميم در كيلوگرم خاك و زمان برداشت (بلوغ تجاري و 10 روز پس از
آن) بر غلظت كادميم، برخي شاخص هاي رويشي و بيوشيميايي در سه توده ي اسفناج بومي ايران (ورامين 1، ورامين 2 و همدان بررسي شد. اثرتيمارهاي كادميم بر ميزان كادميم ريشه، پرولين برگ و وزن خشك اندام هوايي در سطح 1% و برغلظت كادميم اندام هوايي در سطح 5% معني دار بود؛ اثرات متقابل تيمارهاي توده اسفناج، غلظت كادميم و زمان برداشت بر غلظت كادميم و وزن خشك اندام نيز هوايي معني دار بود( p≤0/05). بيشترين غلظت كادميم، در بخش هوايي توده ورامين 1 در برداشت دوم بود (mg/Kg. DW 112/26) و با غلظت كادميم در بخش هوايي اين توده در برداشت اول در هر دو تيمار سطح بالاتركادميم و با توده ورامين 2 در تيمار 60 ميلي گرم كادميم در كيلو گرم خاك ( به ترتيب 95/23، 101/76 و 110/08 ميلي گرم در كيلوگرم وزن خشك) تفاوت معني داري نداشت. ورامين - 1 بيشترين پرولين برگ را داشت (66/69 ميلي گرم در گرم). در هر دو تيمار سطح بالاتركادميم، توده همدان بيشترين وزن خشك
اندام هوايي در برداشت دوم را داشت (5/18 و 3/36 گرم) كه با وزن خشك توده ورامين- 2 در غلظت 30 ميلي گرم كادميم در كيلوگرم خاك در برداشت مشابه، اختلاف معني داري نداشت. بالاترين غلظت كادميم ريشه در توده ورامين- 2 وجود داشت . ( 61/73 mg/Kg. Dw) نتايج اين پژوهش واكنش متفاوت توده هاي اسفناج به سطوح مختلف غلظت كادميم را تاييد نمود.
چكيده لاتين :
Introduction Spinach belongs to sugar beets family (Chemopodiacea) and is native to central Asia and possibly originated from Iran. It is rich in vitamins and minerals such as A, K, C, E, Br and B6. Heavy metal concentration in spinach is a major concern. In particular, Cd can be accumulated in spinach at a toxic level about 2000 times more compared to other heavy metals. The aim of this research was to investigate the Cd concentration in different parts of three spinach genotypes in a Cd contaminated soil.
Methods and Materials This study was carried out at the Research farm of Department of Horticulture Shahid Chamran university in winter 2012 (1391 in Iranian calendar). The experimental design was a split factorial in a randomized complete block with three replications. The factors included three spinach genotypes (Veramin 1 and 2 and Hamadan), three levels of CdCl2 applications (0, 30 and 60 mg kg-1 Cd) and two dates of harvesting time (commercial maturity and 10 days after). Each experimental unit included 3 pots containg 3 kg of soil per unit. Soil properties included: ECe of 3 dS m-1, pH of 7.06, organic matter of 0.82%, 0.17 mg kg-1 of Cd, and soil texture of loamy sand. After CdCl2 application, the contaminated soils were put through different wetting and drying cycles for one month. One seedling was kept in each pot and crops were harvested at the dates described earlier. Cd concentration of crops was measured by atomic absorption (GBC-Savantea). Perolin was measured by methods of Bates et al., and total cholorophyle by the method of Lichateataler. Data was analyzed by SAS and the means were compared by Dunken’s method.
Results Results indicated that the effects of different Cd treatments on Cd concentrations of roots and shoots perolin, dry weigh of shoots were significant (P≤0.01). The interactive effects of all experimental treatments including Cd application, genotypes and date of harvesting on Cd concentration of shoots, dry weight of shoots were significant (P≤0.05). The highest Cd concentration of shoots (112.26 mg kg-1) was found in Veramin 2 and the 2nd date of harvesting. Veramin 1 had the highest perlin concentration (66.69 mg kg-1). In other treatments, Hamdan genotype revealed the highest dry weight of biomass and the 2nd harvesting (5.18 and 3.36 g) and had no significant difference with Veramin 2 and the treatment of 30 mg kg-1 Cd application. The highest Cd concentration of roots was associated with Veramin 2 genotype (61.73 mg kg-1).
Increasing the Cd concentration had negative effect on chlorophyll contents. The chlorophyll contents were 8.58 and 6.19 mg g-1 for 0 and 60 mg kg-1 Cd application rates, respectively. The harvesting time treatments had significant effects on chlorophyll contents. At the first harvesting time, the chlorophyll content was 9.13 mg g-1 while the lowest chlorophyll content (4.55 mg g-1) was at the second harvesting time with and 60 mg kg-1 Cd application. The three genotypes had no significant difference of the chlorophyll content at the first harvesting time, though the genotype of Veramin2 had the highest chlorophyll content at the second harvesting time.
Conclusion Results of this study showed different responses of spinach gentotypes to Cd application treatments. The accumulation of Cd on roots and shoots of these genotypes were different. Veramin 1 had the lowest Cd accumulation in shoots. Increasing Cd concentration from 30 to 60 mg kg-1 resulted in increase of Cd accumulation of shoots compared to roots (1.02 to 1.2 times); this suggest the higher toxicity vulnerability of Cd to roots compared to shoots. However, the ratio of Cd accumulation in root to shoot was less in Veramin 1 compared to other genotypes The Cd accumulations for Veramin 1, Veramin 2 and Hamedan genotypes were 075, 1.04 and 0.97, respectively. The high Cd accumulation of shoots of different genotypes at control treatment suggested that the Cd accumulation of all Iranian genotypes need to be investigated.
