Res. on Crops 12 (2) : 471-478 (2011)

1. Res. on Crops 12 (2) : 471-478 (2011) With one figure Printed in India Effect of chemical and biological soil amendments on production and soil seed bank of annual medic (Medicago scutellata cv. Robinson) G. SHABANI*, M. R. CHAICHI1, M. R. ARDAKANI, J. K. FRIEDEL2, K. KHAVAZI3 AND H. R. ESHGHIZADEH4 Agriculture Research Center Karaj Branch, Islamic Azad University, Karaj , Iran *(e-mail : bb1379@yahoo.com) (Received : February, 2011) ABSTRACT In order to study the effect of different fertilizing systems consisting of control (no fertilizer), chemical, biological and its combination fertilizer on forage yield and conservation of soil seed bank of annual medic (Medicago scutellata cv. Robinson), an experiment was conducted based on a complete randomized block design with three replications in two locations under dry farming conditions in Kermanshah province, Iran, in 2009. The results showed that the highest amount of cumulative biomass of 4185 kg/ha was produced in urea fertilizer+phosphorus solubilizing bacteria+mycorrhiza treatment, and the lowest amount (3183 kg/ha) was observed in nitrogen fixing bacteria+mycorrhiza treatment, respectively. The number of pods in soil seed bank was significantly influenced by different fertilizing systems. The highest number of 314.6 pods per square metre was found in nitrogen fixing bacteria+phosphorus solubilizing bacteria treatment and the lowest of 139.8 pods per square metre in control treatment, respectively. Also the highest yield of pods (1147.2 kg/ha) was obtained in nitrogen fixing bacteria+phosphorus solubilizing bacteria application, while the lowest pod yield of 446 kg/ha was found in control treatment. Key words : Bio-fertilizers, medic, Medicago scutellata cv. Robinson, mycorrhiza, nitrogen fixation, solubilizing bacteria INTRODUCTION wheat in dry climatic condition (Weston et al., 1996). Efficient management and farming A set of seeds which stays intact and practices in the framework of a series of alive in the soil because of various reasons agricultural activities can increase such as seed hardiness or lack of the right agricultural production in the regions with conditions for germination, is called the Soil limited rainfall (Ryan, 2008). Ley-farming Seed Bank. Medic soil seed bank changes with system, in which a grain crop and annual regard to both growth conditions in of different medic pasture alternate each other in a short areas and the intensity and duration of grazing term rotation, is one of the popular agricultural during the pasture period (Christiansen and systems to fulfill food production in dry regions Cocks, 1994). If the seed reserve in soil is less (Oram, 1990). In rotation with other than 260 seed containing pods per square agricultural crops, annual medics have high metre, the natural regeneration of annual water use efficiency and this characteristic medic will not be successful (Kassaim, 1979). makes them a suitable crop in rotation with However, this criterion varies with different Agronomy Department, College of Agriculture, University of Tehran, Karaj, Iran. 1 Department of Sustainable Agricultural Systems, University of Natural Resources and Life Sciences, 2 Vienna, Austria. Soil and Water Research Institute, Iran. 3 College of Agriculture, Ferdowsi University of Mashhad, Iran. 4

2. 472 Shabani, Chaichi, Ardakani, Friedel, Khavazi and Eshghizadeh medic species and varieties, for instance in observed that using of phosphate solubilizing the case of Medicago rigidula about 600 pods, bacteria increased nutrient absorption of and for Medicago scutellata only 250 pods per potassium, phosphorus and forage yield. square metre will suffice (Francis, 1988). Azizi Considering the importance of producing (2003) reported that spring planting of annual adequate forage alongwith maintaining an medic and a maximum of one harvest in the active seed bank in soil in ley-farming system beginning stage of flowering can supply soil and dry farming conditions, this experiment seed bank and produce a considerable amount was conducted to investigate the effect of of dry foliage. different fertilizing systems on the forage yield Biological fertilizers are popular for and seed bank reserves of annual medic (cv. their efficiency to supply phosphorus and other Robinson) under dry farming conditions. necessary nutrients for plants. The phosphorus solubilizing bacteria are the effective MATERIALS AND METHODS microorganisms in this process. These bacteria have a high efficiency to promote plant This experiment was conducted in two growth through providing P in its absorbable locations : 1. Sararood Dryland Farming forms for plants. Mycorrhiza fungi are among Research Station with the geographic longitude of 47′′, 20′ and latitude of 34′′, 20′ and the most important non-destructive microorganisms existing in most soils. elevation of 1351 metres above the sea level, According to the existing estimates, about 71% and 2. Mahidasht Soil Fertility Research Station with the geographic longitude of 46′′, of the live biomass of soil microbial 50′ and latitude of 24′′, 16′ with elevation of community contains mycelium of this fungus (Mukerji and Chamola, 2003). A symbiotic 1380 metres above the sea level, in 2009 interaction between mycorrhiza and phosphate growing season. The experiment was solubilizing bacteria can cause better moisture conducted in a randomized complete block absorption from the soil by plants (Novella design with three replications. Soil samples Legva et al., 2003). have been taken before the commencement Application of Glomus macrocarpam and of the experiment (Table 1). The experimental Rhizobium bacteria in Phaseolus mungo L. treatments consisted of : Control (without cultivation caused a significant increase in fertilizer) (T 1 ), Urea fertilizer+triple yield and the amount of phosphorus and superphosphate fertilizer (T 2 ) * , Urea nitrogen in the grain at the harvest time. Also fertilizer+phosphorus solubilizing bacteria (T3), the water uptake efficiency in fungi and Table 1. Selected physical and chemical characteristics of soil bacteria treatment was higher compared to (0-30 cm depth) in two experimental sites other treatments (Sheela and Sundaram, Characteristics Experimental stations 2003). It has been reported that VAM fungi has a synergetic relation with other microorganisms Sararood Mahidasht such as phosphate solubilizing bacteria (PSB) pH 7.68 7.93 and other plant growth promoting Dissolved solids (EC 103) 30.0 55.0 microorganisms (Azcon, 1989). Toro et al. Organic carbon (%) 0.31 0.62 (1988) studied annual medic response to CaCO3 (%) 30 28 combined inoculation of PSB, Enterobacter sp. Olsen phosphorus (mg/kg) 8.00 9.40 Available potassium (mg/kg) 530 430 and G. mossacee and found that mycorrhizal DTPA extractable Zn (mg/kg) 0.38 1.56 plants in every condition had a better growth. DTPA extractable Cu (mg/kg) 0.70 1.40 Neumann and George (2004) found that plant DTPA extractable Fe (mg/kg) 2.00 4.76 DTPA extractable Mn (mg/kg) 2.42 3.78 phosphorus content between mycorrhizal and Soil texture Loamy silt Loamy clay non-mycorrhizal sorghum was not significantly Urea fertilizer+mycorrhiza (T 4 ), Urea different. The superiority of combined fertilizer+phosphorus solubilizing bacteria+ inoculation of Azotobacter sp. and Rhizobium mycorrhiza (T5), Nitrogen fixing bacteria+triple sp. on bean yield and minerals uptake has superphosphate fertilizer (T6), Nitrogen fixing been reported by Rodelas (1999). In an bacteria+phosphorus solubilizing bacteria (T7), experiment by Piccini and Azcon (1987) on the Nitrogen fixing bacteria+mycorrhiza (T8) and effect of phosphate solubilizing bacteria and nitrogen fixing bacteria+phosphorus mycorrhiza fungi on annual medic, it was

3. Production and soil seed bank of annual medic 473 solubilizing bacteria+Mycorrhiza (T9). Triple the laboratory and after segregating the seeds superphosphate and urea were applied from the soil, the samples were passed according to soil test to fulfil the requirements through sieve number 8 and 10; hence, all of the crop in each site. impurities were removed from the samples. Land preparation practices, including Then the content of ground samples was plowing, disking and furrowing were done passed through sieve number 8 and 10 which before planting in early March. Medic seed were placed on top of each other, respectively, was planted in both the locations in the second in order to segregate the particles, in a way half of March by hand. Every experimental plot that stone, gravel and sand particles were left consisted of six planting rows of 25 cm distance at the bottom of the container. The process with 5 m in length. The annual medic (cv. of adding water to the container and passing Robinson) seeds were planted at the rate of 20 through the sieves was repeated until the kg of seed per hectare. Before sowing the water added to the container became clear. seeds, based on soil analysis (Table 1), and In order to verify that no seeds were left according to fertilizer recommendation for among the gravel and sand in the container, annual medic, half of urea fertilizer and all the contents were placed in 25% salt water phosphorus fertilizer (in treatments and the seeds floating on the surface of the containing chemical fertilizer) were applied to salt water were collected. The soil seed bank the soil in bands by hand. The rest of the population was measured by gathering, nitrogen fertilizer was broadcasted on the plots weighing and counting the seeds from the salt when plants reached to four-leaf stage. water surface. To analyze the experimental Phosphate solubilizing bacteria, nitrogen data and draw the charts, SAS and Excel fixing bacteria and mycorrhiza solutions were software were used, respectively. Comparisons prepared according to the Water and Soil of all means were done on a 5% probability Research Institute instructions. After level based on a least significant difference calculating the amount of seed per treatment, (LSD) method. the seeds were put inside a polyethylene bag (30 mg of each inoculation substance for 100 g RESULTS AND DISCUSSION of seed) alongwith 4% gum arabic solution. Then the seed and the adhesive substance Forage Production at Early Flowering Stage were gently shaken for 30 sec. Then one gram of inoculation substance was added to the Different fertilizing systems had a adhesive seeds and after 45 sec of shaking and significant effect on dry matter weight at early making sure that the inoculation substance flowering stage (Table 3). The highest dry was uniformly distributed among the seeds, matter weight at early flowering stage was the inoculated seeds were spread on an observed in urea fertilizer plus triple aluminum sheet in shade to dry off. Then the superphosphate treatment (T2). Using urea seeds were promptly planted. The seeds were fertilizer+triple superphosphate treatment planted one centimeter deep within the sowing increased the yield by 7.6% compared to control lines. (Table 5). This result could be explained by the At the early flowering stage and after ability of chemical fertilizer to supply readily elimination of border effects, random samples nitrogen and phosphorus nutrients needed for of one square metre were cut to the third node plant growth. This characteristic of chemical height from ground level in each experimental fertilizer is more efficient, especially in the plot. The harvested samples were oven dried early period of plant growth which adequate at 70°C for 24 h. The dried weight was moisture is available in dry land conditions. measured as forage yield. The other measured It seems that in this treatment due to the traits were biomass in re-growth, pod and seed availability of nitrogen in the early stages of yield, cumulative biomass and soil seed bank. growth, faster growth is achieved with less need At the end of experimental period, soil for weather heat units. This result is supported samples were randomly taken from 0 to 5 cm by the other study by Akbari et al. (2009) who in depth in each plot in both experimental reported that application of chemical fertilizer locations using an auger to measure the soils at different growth stages would need less heat seed bank. The soil samples were taken to units to promote plant growth.

4. 474 Shabani, Chaichi, Ardakani, Friedel, Khavazi and Eshghizadeh Re-growth Biomass Production stage in Mahidasht Station (Table 2) could explain 17.26% more dry matter production in Effect of fertilizing systems on the re- this station (Table 4) compared to Sararood growth biomass was significant (Table 3). The (Dryland Research Institute Station). highest re-growth biomass of 2581 kg/ha observed in nitrogen fixing bacteria+ Cumulative Biomass Production phosphorus solubilizing bacteria (T7) followed by urea chemical fertilizer+solubilizing+ Cumulative biomass was significantly mycorrhiza treatment (2552 kg/ha) (Table 5). affected by fertilizing systems (Table 3). The This result indicates the beneficial effect of mean comparison showed that the highest integrated fertilizing system in nutrient supply amount of cumulative biomass of 4185 kg/ha especially in later stages of growth. It seems was produced in T5 treatment (Table 5), and that these treatments could provide with better the lowest amount of 3183 kg/ha was observed photosynthetic activities which lead to better in T8 treatment, respectively. In an experiment plant growth. In an experiment by Zaidi and that sorghum seed was inoculated by B. Khan (2006), it was reported that inoculation of cepucia, P. fluorecens or Enterobacter the plant the vetch seed with a mixture of plant growth growth was increased, however, the double and promoting bacteria, nitrogen fixing bacteria and triple inoculation was not effective on plant mycorrhiza fungi, significantly improved dry growth (Chiarini et al., 1998). Ardakani et al. matter. Adequate rainfall during re-growth (2001) reported that combined application of mycorrhiza and Streptomyces on wheat yield, Table 2. Average precipitation and temperature during annual had a decreasing effect when compared with medic growing season in two experimental sites application of mycorrhiza alone. This is Month Average precipitation Average temperature probably due to the sensitivity of mycorrhiza (mm) (°C) fungi to antibiotic substances which are secreted by Streptomyces. Research results Sararood Mahidasht Sararood Mahidasht have shown that seed inoculation with a February 18.3 21.2 7.3 6.4 mixture of several microorganism increased March 36.1 71.8 9.4 8.0 nutrient absorption and yield, compared with April 15.2 12.4 16.2 14 sole inoculation with each one of them May 0.2 0.9 22.7 19.7 June 0 0 26.5 24.0 (Perveen et al., 2002). Other research works Table 3. Degree of freedom and measuring F values of annual medic agronomic characteristics as affected by different fertilizing systems, grown in two experimental sites (Sararood and Mahidasht Experimental Stations) at dry farming conditions S. O. V. d. f. Forage yield RGB AB SSB Pod yield Pr > F Location (L) 1 0.3638 0.0073 0.9885 0.0878 0.9885 Fertilizer treatment (FT) 8 0.3148 0.0794 <0.0001 <0.0001 <0.0001 L × FT 8 0.3652 0.1057 0.1413 0.0015 0.1413 RGB : Re-growth biomass, AB : Accumulative biomass, SSB : Soil seed bank. Table 4. Mean comparison of annual medic traits as affected by different fertilizing systems in two experimental sites (Sararood and Mahidasht) under dry farming system Site Forage RGB AB Pod yield SSB 2 (kg/ha) (kg/ha) (kg/ha) (kg/ha) (pods/m ) Sararood 1329a 2045.6b 3439a 831.8a 229.5a Mahidasht 1410a 2472.5a 3630a 831.2a 245.9a LSD (P=0.05) 220.8 235.3 567.7 100.8 20.3 RGB : Re-growth biomass, AB : Accumulative biomass, SSB : Soil seed bank. Means with the same letter in each column are not significantly different at 5% probability level.

5. Production and soil seed bank of annual medic 475 Table 5. Mean comparison of studied traits in different soil nutrient systems in annual medic (Medicago scutellata cv. Robinson) under dry farming culture Fertilizing systems Forage yield RGB CB Pod yield SSB (kg/ha) (kg/ha) (kg/ha) (kg/ha) (pods/m2) T1 1292b 1909b 3201±187b 446.7f 139.8e T2 1486a 2108b 3285±164b 704.2e 242.2bc T3 1328b 2273ab 3502±138ab 910.2bc 260.0b T4 1337b 2158ab 3496±62ab 865.7bcd 241.5bc T5 1397ab 2552a 4185±259a 740.2de 198.3d T6 1369ab 2295ab 3727±72ab 799.8cde 210.8cd T7 1386ab 2581a 3576±448ab 1147.2a 314.6a T8 1401ab 2184ab 3183±414b 976.7b 278.8ab T9 1327b 2268ab 3649±190ab 893.0bc 253.4b LSD (P=0.05) 149 428 699.0 152.2 40.8 RGB : Re-growth biomass, CB : Cumulative biomass, SSB : Soil seed bank. Means with the same letter in each column are not significantly different at 5% probability level. Fertilizing systems : Control (without fertilizer) (T1), chemical, biological and integrated fertilizing systems of nitrogen and phosphorus as follows : Urea fertilizer+Triple superphosphate fertilizer (T2), Urea fertilizer+Phosphorus solubilizing bacteria (T3), Urea fertilizer+Mycorrhiza (T4), Urea fertilizer+Phosphorus solubilizing bacteria+Mycorrhiza (T5), Nitrogen fixing bacteria+Triple superphosphate fertilizer (T6), Nitrogen fixing bacteria+Phosphorus solubilizing bacteria (T7), Nitrogen fixing bacteria+Mycorrhiza (T8) and Nitrogen fixing bacteria+Phosphorus solubilizing bacteria+Mycorrhiza (T9). scutellata and M. rigidula species around 600 also indicate that if phosphorus solubilizing and 250 pods per square metre are sufficient, bacteria were applied with Glomus mossea, a respectively (Francis, 1988). significant increase in the growth of annual In this experiment, application of medic could be achieved (Piccini and Azcon, nitrogen fixing bacteria+phosphorus 1987). solubilizing bacteria treatment led to sufficient seed production and rich soil seed bank Soil Seed Bank ensuring natural regeneration. Plants in T7, T8, T3 and T9 treatments with 314.6, 278.8, 260 Based on the results (Table 3), the and 253.4 pods per square metre, respectively, number of pods in soil seed bank was were able to complete their physiological significantly influenced by different fertilizing growth period soon after the first harvest at systems. The highest number of 314.6 pods the beginning stage of flowering. This per square metre was found in nitrogen fixing phenomenon could help the plant to produce bacteria+phosphorus solubilizing bacteria more seed to support soil seed bank which treatment and the lowest of 139.8 pods per makes these treatments more suitable for square metre in control treatment, application in Ley-farming system. Similarly respectively (Table 5). The superiority of to this result, Wasule et al. (2002) in a field combined inoculation of nitrogen fixing experiment on soybean indicated that there bacteria+phosphorus solubilizing bacteria on was a positive and synergistic interaction plant growth caused a significant increase in effect between Bradyrhizobium bacteria and number of pods in soil seed bank. A proper phosphorus solubilizing bacteria (Pseudomonas fertilizing system is necessary for annual putida). medic to ensure the capability of plant to produce adequate amount of seed in soil seed Pod Yield bank for a successful natural regeneration. Critical levels of soil seed bank for successful Pod yield was significantly affected by re-establishment of annual medic pasture in fertilizing systems but interaction with local Ley-farming system is an average of 400 pods condition was not significant (Table 3). The per square metre, although this critical level highest yield of pods (1147.2 kg/ha) was for various species of annual medic is different. obtained in nitrogen fixing bacteria+ For example, in different cultivars of M.

6. 476 Shabani, Chaichi, Ardakani, Friedel, Khavazi and Eshghizadeh phosphorus solubilizing bacteria application, Table 6. Simple correlation coefficients between measured traits of annual medic as affected by fertilizing system while the lowest pod yield of 446 kg/ha was found in control treatment (Table 5). De Freitas Trait RGB SSB Pod yield Forage yield CB et al. (1997), in canola, Cakmakc et al. (1999) RGB 1 in sugarbeet and De Freitas (2000) in wheat SSB 0.21ns 1 conducted experiments and all more or less Pod yield 0.25ns 0.77** 1 concluded that seed inoculation with these Forage yield 0.29* 0.10ns -0.03ns 1 bacteria significantly increased the grain CB 0.53** 0.03ns -0.05ns 0.31* 1 yield, yield components and total dry matter RGB : Re-growth biomass, AB : Accumulative biomass, production. SSB : Soil seed bank. There were positive significant *,**Significant at P=0.05 and P=0.01 levels, respectively. NS : Not Significant. correlations between cumulative biomass with experiment showed that by application of re-growth biomass, as well as seed yield with proper fertilizer on annual medic (M. scutellata pod yield and soil seed bank reserves (Table cv. Robinson) and harvesting a forage yield at 6). Pod yield had a higher correlation (r=0.77**) early flowering stage, not only a considerable with soil seed bank than other traits, also amount of forage could be produced, but also cumulative biomass with biomass in re-growth an active soil seed bank could be achieved had a relatively high correlation. Positive which was the main goal of this experiment. correlation between seed yield and pod with In urea chemical fertilizer+solubilizing+ the soil seed bank revealed a direct mycorrhiza (T5) treatment application although relationship of seed yield with available pod in the highest vegetative growth was achieved, soil seed bank. Application of proper fertilizing but due to the lack of sufficient seed production, system can have a positive effect on the growth seed bank was poor. However, in a Ley-farming of annual medic. The results of this Sararood Station Mahidasht Station LSD0.05=57.7 480 400 Soil seed bank (pods/m2) 320 240 160 80 0 T1 T2 T3 T4 T5 T6 T7 T8 T9 Fig. 1. Interaction effects of region and different fertilizer treatments on seed bank of annual medic at dryland conditions.

7. Production and soil seed bank of annual medic 477 system, when the regeneration and natural De Freitas, J. R. (2000). Yield and N assimilation of winter wheat (Triticum aestivum L. cv. establishment of annual medic is the main Norastar) inoculated with rhizobacteria. goal, the application of nitrogen fixing Pedobiologia 44 : 97-104. bacteria+phosphorus solubilizing bacteria De Freitas, J. R., Banerjee, M. R. and Germida, treatment is best recommended under the J. J. (1997). Phosphate-solubilizing environment conditions of this experiment. rhizobacteria enhance the growth and yield but not phosphorus uptake of canola ACKNOWLEDGEMENT (Brassica napus L.). Biol. Fertil. Soil 24 : 358-64. The authors would like to thank the Francis, C. M. (1988). Selection and agronomy of personnel of the Water and Soil Research medics for dry land pasture in Iran. Project Division of Kermanshah Agriculture and Tcp/ IRAN/6652. Kassaim, K. K. (1979). Study on some factors Natural Resources Center and the Dryland affecting the establishment of annual Farming Research Institute (Sararood) for medics (Medicago sp.) under rainfed region their cooperation in carrying out this project. in North Iraq. Mosul University College of Agriculture and Forestry. 155 p. REFERENCES Mukerji, K. G. and Chamola, B. P. (2003). Comendium of Mycorrhizal Research. A. P. H. Akbari, P., Ghalavand, A. and Modarres Sanavi, S. Publisher, New Dehli. p. 310. A. M. (2009). Effect of different fertilizing Neumann, E. and George, E. (2004). Colonization systems and bacteria of incremental with the Arbuscular Mycorrhiza Fungus growth on phenology, yield and yield Glomus mosseae (Nicol & Gerd) enhanced components of sunflower. Electron. J. Crop phosphorus uptake from dry soil in Produc. 2 : 134-19 (In Persian, Abstract in Sorghum bicolor (L.). Plant and Soil 261 : English). 245-55. Ardakani, M. R, Mazaheri, D. and Noormohammadi, Novella Legva, R., Machado Alcolea, A. M., Ladeon G. (2001). Effect of Azospirillum, mycorrhiza de Gaevara, M. C. and Vega Brizuelas, A. and streptomyces with manure in yield and (2003). Participation of biofertilizers in the yield components of wheat (Mahdavi var.). production of multiple crops (Beans– J. Agric. Sci. 7 No. 1 (In Persian, Abstract Maize). Alimentaria 40 : 133-35. in English). Oram, R. N. (1990). Register of Australian herbage Azcon, R. (1989). Selective interaction between plant cultivar. CSIRO, Australia. 304 p. free-living rhizosphere bacteria and Perveen, S., Khan, M. S. and Zaidi, A. (2002). Effect vesicular- arbuscular mycorrhizal fungi. of rhizospheric microorganisms on growth Soil Biol. Biochem. 21 : 639-44. and yield of greengram (Phaseolus radiatus). Azizi, Kh. (2003). Influence of Agro-technical factor Indian J. agric. Sci. 72 : 421-23. on seed bank in soil, establishment and Piccini, D. and Azcon, R. (1987). Effect of natural self-regeneration of annual medics phosphate-solubilizing bacteria and and reserve of soil moisture. Ph. D. thesis, vesicular-arbuscular mycorrhizal fungi on Tarbiat Modaress University Iran. pp. 125 the utilization of bayavor rock phosphate (In Persian, Abstract in English). by alfalfa plants using a sand vermiculate Cakmakc, I. R., Kantar, F. and Algur, O. F. (1999). medium. Plant and Soil 101 : 45-50. Sugarbeet and barley yield in relation to Rodelas, B. (1999). Influence of Rhizobium- Bacillus polymyxa and Bacillus megaterium Azotobacter combined inculcation on var. phosphates inculcation. J. Plant Nutr. mineral composition of faba bean (Vicia Soil Sci. 162 : 437-42. faba L.). Biol. Fertil. Soil 29 : 165-69. Chiarini, L., Bevivino, A., Tabacchioni, S. and Ryan, J. (2008). Crop nutrients for sustainable Dalmastri, C. (1998). Inocultion of agricultural production in the drought- Burkholderia ceoacia, Pseudomonas stressed Mediterranean region. J. Agric. florescens and Entrobacter sp. on Sorghum Sci. Tech. 10 : 295-306. biocolor : Root colonization and plant growth Sheela, A. M. and Sundaram, M. D. (2003). Role of promotion of dual strain inoculation. Soil VA mycorrhizal biofertilizer in establishing Biol. Biochem. 30 : 81-87. blackgram ( Vigna mungo L.) on the Christiansen, S. and Cocks, P. S. (1994). Change abandoned ash ponds of novel thermal in seed bank size and botanical power plant. Mycorrhiza News 15 : 13-16. composition of medic pastures grown in Toro, M., Azcon, R. and Barea, J. M. (1988). The rotation with barley in North-West Syria. use of isotopic dilution techniques to Al Awamia 87 : 141-48.

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