Mohsin Zafar

Effect of Plant Growth-Promoting Rhizobacteria on Growth, Nodulation and Nutrient Accumulation of Lentil Under Controlled Conditions

Abstract Application of plant growth-promoting rhizobacteria (PGPR) has been shown to increase legume growth and development under field and controlled environmental conditions. The present study was conducted to isolate plant growth-promoting rhizobacteria (PGPR) from the root nodules of lentil ( Lens culinaris Medik.) grown in arid/semi-arid region of Punjab, Pakistan and examined their plant growth-promoting abilities. Five bacterial isolates were isolated, screened in vitro for plant growth-promoting (PGP) characteristics and their effects on the growth of lentil were assessed under in vitro, hydroponic and greenhouse (pot experiment) conditions. All the isolates were Gram negative, rod-shaped and circular in form and exhibited the plant growth-promoting attributes of phosphate solubilization and auxin (indole acetic acid, IAA) production. The IAA production capacity ranged in 0.5–11.0 μg mL −1 and P solubilization ranged in 3–16 mg L −1 . When tested for their effects on plant growth, the isolated strains had a stimulatory effect on growth, nodulation and nitrogen (N) and phosphorus (P) uptake in plants on nutrient-deficient soil. In the greenhouse pot experiment, application of PGPR significantly increased shoot length, fresh weight and dry weight by 65%, 43% and 63% and the increases in root length, fresh weight and dry weight were 74%, 54% and 92%, respectively, as compared with the uninoculated control. The relative increases in growth characteristics under in vitro and hydroponic conditions were even higher. PGPR also increased the number of pods per plant, 1 000-grain weight, dry matter yield and grain yield by 50%, 13%, 28% and 29%, respectively, over the control. The number of nodules and nodule dry mass increased by 170% and 136%, respectively. After inoculation with effective bacterial strains, the shoot, root and seed N and P contents increased, thereby increasing both N and P uptake in plants. The root elongation showed a positive correlation ( R 2 = 0.67) with the IAA production and seed yield exhibited a positive correlation ( R 2 = 0.82) with root nodulation. These indicated that the isolated PGPR rhizobial strains can be best utilized as potential agents or biofertilizers for stimulating the growth and nutrient accumulation of lentil.

Characterization of mineral phosphate-solubilizing bacteria for enhanced sunflower growth and yield-attributing traits

Nineteen isolates of rhizobacteria associated with sunflower (Helianthus annuus L.), collected from various locations in Pakistan, were screened for phosphate solubilization and indole-3-acetic acid (IAA) production. Two potential phosphate-solubilizing bacterial isolates with substantial IAA biosynthesis capacity, Ps-5 and Ss-2, were selected for further study. Based on 16S rRNA gene sequence analysis, isolate Ps-5 was identified as Bacillus sp. and Ss-2 as Alcaligenes faecalis. Both strains were found to be metabolically diverse in terms of the number and amount of different carbon substrates they utilized in the BIOLOG GN2/GP2 microplate assay. High-performance liquid chromatography analysis of the culture supernatant confirmed that Bacillus sp. Ps-5 produced considerable amounts of both lactic and tartaric acids, while A. faecalis Ss-2 secreted only lactic acid. There was a strong positive correlation between phosphate solubilization and organic acid production by both strains. Following inoculation, strain Ps-5 and Ss-2 were found to be good root colonizers and significantly (P ≤ 0.05) increased sunflower growth and phosphorus (P) uptake. However, inoculation had a non-significant (P ≤ 0.05) effect on sunflower yield parameters, including oil contents. Based on these results, we conclude that Ps-5 and Ss-2 are potent plant growth-promoting rhizobacteria strains with the ability to supplement the P requirements of sunflower crops. Further field inoculation studies are needed before these strains can be recommended as bio-inoculants. To the best of our knowledge, this is first report on the association and phytobeneficial potential of A. faecalis with sunflower.

Influence of integrated phosphorus supply and plant growth promoting rhizobacteria on growth, nodulation, yield and nutrient uptake in Phaseolus vulgaris

To guarantee a sufficient phosphorus supply for plants, a rapid and permanent mobilization of phosphorus from the labile phosphorus fractions is necessary, because phosphorus concentrations in soil solution are generally low. Several plant growth-promoting rhizobacteria (PGPR) have shown potential to enhance phosphorus solublization and nodulation of legumes when co-inoculated with Rhizobium . This investigation was undertaken to assess the feasibility and compatibility of two mineral phosphorus fertilizers; diammonium phosphate (DAP), triple super phosphate (TSP), poultry manure (PM) and two PGPR strains on the growth, nodulation, yield, nutrient uptake and protein content of common bean ( Phaseolus vulgaris ) under deficient phosphorus supply. Integrated application of mineral phosphorus (P), PM and PGPR significantly increased shoot height, shoot fresh weight, shoot dry weight and leaf chlorophyll content by 67, 160, 51 and 106%, respectively, while increase in root length, root fresh weight and root dry weight was 79, 161, and 187%, respectively, over unfertilized control without PGPR application. Integrated use of different P sources and PGPR also increased number of nodules per plant, nodule fresh weight and nodule dry weight by 158, 107 and 168% over the control. Treatment with PGPR significantly increased number of pods per plant and grain yield by 224 and 96%, respectively over the control. Co-inoculation with Bradyrhizobium sp. strain MN-S and Agrobacterium sp. strain Ca-18 demonstrated two-fold increase in the proportion of nitrogen (N) and P uptake as well as protein content of the common bean grain was increases by 48%. Therefore, application of PGPR with low P fertilizer rates and PM could be a viable supplementary strategy for maximum benefits in terms of cost of production and sustaining productivity. Key words: Phaseolus vulgaris L., plant growth promoting rhizobacteria (PGPR), nodulation, yield, phosphorus deficiency, protein.

Changes in Soil Properties and Microbial Indices across Various Management Sites in the Mountain Environments of Azad Jammu and Kashmir

The mountainous region of the Himalayas is covered with forest, grassland, and arable land, but the variation in ecosystem functions has not been fully explored because of the lack of available data. This study appraises the changes in soil properties over the course of a year (spring, summer, autumn, winter) for forest, grassland, and arable soils in a typical hilly and mountainous region of Azad Jammu and Kashmir, Pakistan. Soil samples were collected from major land-cover types in the mountain region: natural forest, grassland, and cultivated land (arable). The natural forest served as a control against which changes in soil properties resulting from removal of natural vegetation and cultivation of soil were assessed. Soil samples were collected from depths of 0–15 and 15–30 cm six times during the year and examined for changes in temperature, moisture, electrical conductivity (EC), micronutrients [iron, manganese, copper, and zinc (Fe, Mn, Cu, Zn, respectively)], and microbial population. Significant differences were found in soil temperature, soil moisture, Fe, Mn, Cu, Zn, and number of bacteria, actinomycetes, and fungi among the three land-cover types. Soil under cultivation had 4–5 °C higher temperature and 3–6% lower moisture than the adjacent soils under grassland and forest. Electrical conductivity (EC) values of forest, grassland, and arable soil were 0.36, 0.30, and 0.31 dS m−1, indicating that soil collected from the forest had 18–20% more EC than the adjacent arable and grassland soils. On average, amounts of Fe, Mn, Cu, and Zn in the soil collected from the arable site were 6.6, 5.7, 1.7, and 0.8 mg kg−1, compared with 24.0, 12.1, 3.5, and 1.2 mg kg−1 soil in the forest soil, showing that arable had two to four times less micronutrients than grassland and forest. Populations of bacteria, actinomycetes, and fungi in the forest were 22.3 (105), 8.2 (105), and 2.5 (103), respectively, while arable land exhibited 8.2 (105), 3.2 (105), and 0.87 (103). Season (temperature) and depth showed significant effects on microbial activity and nutrient concentration, and both decreased significantly in winter and in the subsurface layer of 15−30 cm. Different contents of the parameters among arable, grassland, and forest soils indicated an extractive effect of cultivation and agricultural practices on soil. Natural vegetation appeared to be a main contributor to soil quality as it maintained the moisture content and increased the nutrient status and microbial growth of soil. Therefore, it is important to sustain high-altitude ecosystems and reinstate the degraded lands in the mountain region.

Immobilization of Pb and Cu in polluted soil by superphosphate, multi-walled carbon nanotube, rice straw and its derived biochar.

Lead (Pb) and copper (Cu) contamination in croplands pose severe health hazards and environmental concerns throughout soil-food chain transfer. In the present study, BCR, TCLP, CaCl2, and SBET techniques were employed to evaluate the simultaneous effectiveness of rice straw (RS) and its derived biochar (BC), multiwall carbon nanotube (MWCNT), and single superphosphate (SSP) to immobilize the Pb and Cu in co-contaminated soil. The BCR sequential extraction results suggested that with increasing BC and SSP amount, the acid-soluble fractions decreased while oxidizable and residual proportions of Pb and Cu were increased significantly. Compared to SSP, the application of BC amendment substantially modified partitioning of Cu from easily exchangeable phase to less bioavailable residual bound fraction. The immobilized Pb and Cu were mainly transformed to reducible forms. The TCLP and CaCl2-extracted Pb and Cu were reduced significantly by the addition of BC compared to RS and MWCNT, whereas the bio-accessibility of Pb significantly reduced with RS addition. SSP showed better results for Pb immobilization while marginal for Cu in co-contaminated soil. Overall, the addition of BC offered the best results and could be effective in both Pb and Cu immobilization thereby reducing their mobility and bioavailability in the co-contaminated soil.

Animal manure phosphorus characterization by sequential chemical fractionation, release kinetics and 31P-NMR analysis

Phosphate release kinetics from manures are of global interest because sustainable plant nutrition with phosphate will be a major concern in the future. Although information on the bioavailability and chemical composition of P present in manure used as fertilizer are important to understand its dynamics in the soil, such studies are still scarce. Therefore, P extraction was evaluated in this study by sequential chemical fractionation, desorption with anion-cation exchange resin and 31P nuclear magnetic resonance (31P-NMR) spectroscopy to assess the P forms in three different dry manure types (i.e. poultry, cattle and swine manure). All three methods showed that the P forms in poultry, cattle and swine dry manures are mostly inorganic and highly bioavailable. The estimated P pools showed that organic and recalcitrant P forms were negligible and highly dependent on the Ca:P ratio in manures. The results obtained here showed that the extraction of P with these three different methods allows a better understanding and complete characterization of the P pools present in the manures.

EFFECT OF DIFFERENT PHOSPHORUS SOURCES ON THE GROWTH, YIELD, ENERGY CONTENT AND PHOSPHORUS UTILIZATION EFFICIENCY IN MAIZE AT RAWALAKOT AZAD JAMMU AND KASHMIR, PAKISTAN

Effect of poultry manure (PM) and four inorganic phosphorus (P) fertilizers sources, i.e., diammonium phosphate (DAP), single super phosphate (SSP), nitrophos (NP) and triple super phosphate (TSP) on crop production and P utilization efficiency (PUE) of maize was studied. Both inorganic P fertilizers and PM applied alone or combined in 50:50 proportions at equivalent rate of 90 kg P2O5 ha−1. Results indicated that inorganic P sources with PM significantly increased plant height, leaf area and chlorophyll content. Average values showed that combined application of inorganic P with PM increased grain yield by 19 and 41% over inorganic P and PM alone, respectively. Similarly, increase in P-uptake due to the combined application of inorganic P + PM was 17% compared to sole inorganic P. Phosphorus utilization efficiency of inorganic P was increased with PM and the highest PUE was recorded in DAP + PM. Generally, combination of DAP + PM proved superior over the remaining P fertilizers.

Interactive effect of cobalt and nitrogen on growth, nodulation, yield and protein content of field grown pea

Pea (Pisum sativum L.) has increasing nutritional, commercial, and economical value, and initial low supply of N and Co is needed to increase nodulation, yield, and profit. A field experiment in 2010 was conducted at the University of Poonch Rawalakot located in the hilly region of the state of Azad Jammu and Kashmir, Pakistan. The aim of the study was to evaluate the effects of fertilization of N and Co on growth, nodulation, seed yield, seed composition of, and uptake of N and Co by pea plant. Treatments included three levels of N (0, 30, and 60 kg N·ha−1 and represented as N0, N30, and N60, respectively) combined with three levels of Co (0, 10, and 20 g Co·ha−1 and represented as Co0, Co10, and Co20, respectively), and the control represented as N0Co0. Results indicated that most of the morphological characteristics were increased with N60. The greatest shoot length, root length, and chlorophyll content were recorded in the N60Co20. The number of root nodules increased from 6 in the control to 19 with fertilization of N and Co. Yield responses to N-Co fertilization occurred to all rates, and the highest yield, 2536 kg·ha−1, was observed in the treatment N60Co10. Total N and Co uptake in the plant (shoot + root + seed) ranged between 16–147% and 3–331% over the control, while seed protein increased by 13–198% over the control by application of N and Co. This study demonstrates that N- and Co-deficient soils are likely to produce crops with low yields and seeds with low protein levels, and therefore, appropriate management of soil N and Co could be an effective approach to increase and sustain pea production in the small holding mountain ecosystems.

Soil-plant micronutrients dynamics in response to integrated fertilization under wheat–soybean cropping system at Rawalakot, Pakistan

ABSTRACT This study provided an insight on improving soil-plant micronutrients availability in response to poultry manure (PM), wheat milling residues (WMR) and urea N (UN) and their integration in wheat–soybean cropping system. The treatments were: control; poultry manure full, PM100; wheat milling residues full, WMR100; urea N full, UN100; PM half and WMR half, PM50+WMR50; UN50+PM50; UN50+WMR50; UN50+PM25+WMR25. All amendments were added at the rate or equivalent to 100 kg total N ha–1. Results indicated that the integrated treatments increased Cu, Fe, Mn and Zn uptake of wheat by 35.7–103%, 48.4–111.1%, 85.2–267.0% and 33.8–128.2%, respectively over control. In soybean the corresponding increase in micronutrient uptake (Cu, Fe, Mn and Zn) was 18.3–60.3%, 27.5–87.4%, 14.1–54.6% and 13.2–58.0% in integrated treatments. The post-harvest soil analysis indicated 2 to 3-fold increase in micronutrient content with highest values in PM100 i.e., 2.66 mg kg−1 for Cu, 14.41 mg kg−1 for Fe, 18.58 mg kg−1 for Mn and 2.44 mg kg−1 for Zn, respectively. The results showed that the PM either alone or in integrated with WMR and UN can be an effective management strategy for improving micronutrient content of soil–plant.

Introduction of composted rock phosphate and poultry manure enhances winter wheat phosphorus use efficiency, grain yield and soil quality

ABSTRACT This field study evaluates the integrated impact of poultry manure (PM), rock phosphate (RP), composted rock phosphate (CRP) and single super phosphate (SSP) on the growth, yield, and phosphorus use efficiency (PUE) of winter wheat and their effect on postharvest soil characteristics. The seven treatments were as follows: T1 = control; T2 = SSP full; T3 = PM full; T4 = RP full; T5 = CRP full; T6 = 50% SSP + 50% CRP (50:50); T7 = 50% PM + 50% CRP (50:50) at a recommended P rate of 90 kg ha−1. The combined treatment with PM + CRP produced the highest straw yield of 3582 kg ha−1, grain yield of 2226 kg ha−1, P uptake of 21.3 kg ha−1, and PUE of 18%. The postharvest soil organic carbon, total nitrogen and soil available phosphorus were sig-nificantly higher in integrated treatments.