چكيده لاتين :
Background and Objectives: In recent years, the production of healthy foods through environmentally
friendly methods has received much attention. Spinach is a vegetable plant rich in minerals and vitamins which
is used in green and cooked forms. Thus, healthy production of this plant with the greatest quantitative and
qualitative yield is of particular importance. Weeds as unwanted plants in spinach fields can damage this plant
significantly. Nevertheless, spinach is severely sensitive to different herbicides. The goal of this study was to
investigate the effect of plant growth promoting rhizobacteria (PGPR), filter cake and metribuzin herbicide on
growth and mineral nutrition of spinach plant. In this study, the growth and nutritional parameters of spinach
interact with PGPR, filter cake and metribuzin herbicide was also aimed.
Materials and Methods: The spinach seeds (Spinacia oleracea L. Varamin cultivar) were sown in pots
containing 40% field soil and 60% sand (10 seeds in each pots). To investigate the impact of PGPR isolates and
filter cake on concentration of macronutrients (K, Ca, Mg, and P), micronutrients (Cu, Zn, and Fe) and leaves
dry weight, Pseudomonas protogenes CHA0 (CHA0) as a reference strain, P. alloputida RUM14 (RUM14)
which was collected from Iranian field soil and 3% by weight of fresh filter cake (F3%) were used. Spinach
seedlings were inoculated for 14 days with 50 mL of bacteria strains suspension with optical density one
(OD600=1). 3% by weight of filter cake were mixed to soil of pots before sowing the seeds. Metribuzin herbicide
at three levels (0 (H0), 50 (H1) and 100 (H2) grams per hectare) were used. The effects of PGPR, filter cake and
metribuzin herbicides and their interactions were also studied (CHA0 + F0 + H1, RUM14 + F0+ H1, CHA0 + F0
+ H2, RUM14 + F0 + H2, B0 + F3% + H0, B0 + F3% + H1, B0 + F3% + H2, CHA0 + F3% + H1, RUM14 +
F3% + H1, CHA0 + F3% + H2, RUM14 + F3% + H2). The experiment had a randomized complete block design
with three replications. The treatments (3 metribuzin herbicide × 2 filter cake × 3 PGPR) were arranged in
factorial combination. The statistical analysis was performed using Duncan’s multiple range test at 5%
probability level.
Results: Statistical analysis revealed that the application of PGPR (CHA0 and RUB14), filter cake, and their
interaction increased tissue plant concentration of macronutrients, micronutrient and leaf dry weight of spinach
plant. Statistically, the highest concentration of P, K, Ca, and Mg macronutrients (5583.30, 83000.00, 10886.70,
10766.60 mg kg-1 dry matter, respectively), Cu, Zn, and Fe micronutrients (22.73, 73.00, and 221.36 mg kg-1 dry
matter, respectively) and dry weight of leaves (8.76 g) was observed in treatment of combination of PGPR and
filter cake. The application of Metribuzin herbicide led to decline the concentration of macronutrients,
micronutrient, and leaf dry weight of spinach plant. The decline increased with increasing herbicide
concentration. The lowest concentration of P, K, Ca, and Mg macronutrients (3233.30, 48867.00, 6403.30, and
6283.30 mg kg-1 leaf dry weight, respectively), Cu, Zn, and Fe micronutrient (4.40, 19.50, and 132.66 mg kg-1,
respectively), and leaf dry weight (2.83 g) was observed in B0+F0+H2 treatment (using just herbicide 100 g ha-
1). However, the detrimental effect of herbicide on leaf dry weight and mineral nutrition of spinach plant were
alleviated using the PGPR (CHA0 and RUB14) and filter cake (F3%) either alone or together (RUM14+F3%,
CHA0+F3%). Statistically, the greatest alleviation of the detrimental effect of herbicide was observed in the
treatment of RUM14+F3%. Conclusion: The results of this research showed that inoculation of spinach with Pseudomonas PGPR (P.
protogenes CHA0, P. alloputida RUM14) with and without filter cake not only improved the growth and
mineral nutrition of spinach plant, but also alleviated the detrimental effect of herbicide in the plant. In general,
the proper function of PGPR and filter cake in spinach plant growth is due to 1- Supplying more nutrients to the
spinach plant due to filter cake rich in nutrients 2- The ability of Pseudomonas bacteria to induce resistance of
the plants to stress and supply of some nutrients such as iron due to its ability to produce siderophore 3- Supply
of food by filter cake for further growth of PGPR and the possibility of increasing the population of these
bacteria. 4- Filter cake rich in organic matter can improve the physical and biological properties of the soil and
can provide the better conditions for plant growth and nutrition. The results of this research showed that P.
alloputida RUM14 and filter cake can be used as biological and organic fertilizers.
