K-priming positively modulates growth and nutrient status of salt-stressed cotton (Gossypium hirsutum) seedlings

Being macronutrient, K⁺ is involved in a number of metabolic processes including stimulation of over 60 enzymes. The present study was conducted to investigate whether K-priming could alleviate the effects of salinity on the growth and nutrient status of cotton seedlings. The seeds of two cotton cultivars, namely FH-113 and FH-87, were primed with solutions of three potassium sources (KNO₃, K₂SO₄ and K₂HPO₄) using three concentrations (0%, 1.25% and 1.5%) of each potassium source. After 1 week of germination, the seedlings were subjected to salinity (0 and 200 mM NaCl) stress. The results showed that salinity significantly affected growth and nutrients status of cotton seedlings. The K-priming alleviated the stress condition and significantly improved dry matter as well as nutrient uptake in cotton seedlings. Of the priming treatments pre-sowing treatment with KNO₃ (1.5%) was most effective in increasing shoot and root lengths and biomass of cotton seedlings. The seedlings raised from seed treated with KNO₃ (1.5%) showed varied accumulation of cations (Ca²⁺, Na⁺ and K⁺) and faced less oxidative stress irrespective of cotton cultivars under salt stress. The results suggested that pre-sowing seed treatment with KNO₃ (1.5%) might be recommended for synchronized germination and sustainable production of cotton crop under saline environments.     

Minimizing ammonia volatilization from urea,improving lowland rice (cv. MR219) seed germination,plant growth variables,nutrient uptake,and nutrient recovery using clinoptilolite zeolite

The anionic nature and high cation exchange capacity (CEC) of clinoptilolite zeolite can be exploited to reduce ammonia (NH₃) loss from urea and to improve soil chemical properties to increase nutrient utilization efficiency in lowland rice cultivation. A closed-dynamic airflow system was used to determine NH₃ loss from treatments (20, 40, and 60 g clinoptilolite zeolite pot^?1). Seed germination study was conducted to evaluate the effects of clinoptilolite zeolite on rice seed germination. A pot study was conducted to determine the effects of clinoptilolite zeolite on rice plant growth variables, nutrient uptake, nutrient recovery, and soil chemical properties. Standard procedures were used to determine NH₃ loss, rice plant height, number of leaves, number of tillers, dry matter production, nutrient uptake, nutrient recovery, and soil chemical properties. Application of clinoptilolite zeolite (15%) increased shoot elongation of seedlings and significantly reduced NH₃ loss (up to 26% with 60 g zeolite pot^?1), and increased number of leaves, total dry matter, nutrient uptake, nutrient recovery, soil pH, CEC, and exchangeable Na⁺. Amending acid soils with clinoptilolite zeolite can significantly minimize NH₃ loss and improve rice plant growth variables, nutrient uptake, nutrient recovery, and soil chemical properties. These findings are being validated in our ongoing field trials.     

Alleviation of ionic and osmotic stress of salinity in seedling emergence of Lolium perenne L. with halopriming treatments growing in an hydroponic system

In this paper, we presented a simple and inexpensive model of hydroponic system in laboratory. The six halopriming treatments were used in research. One-third strength nutrient solutions used in hydroponic systems. The ionic and osmotic stresses were induced by adding sodium chloride (NaCl) or polyethylenglycol-6000 to the nutrient solution. Each treatment was conducted three replications in a completely randomized design. The results showed that haloprimig significantly decreased the management (MGT) of Lolium perenne as compared with control. Haloprimed with NaCl for 72, 48 h and magnesium chloride (MgCl₂) for 24 and 72 h showed significant difference as compared with non-treated seed in same stress level. Indeed, it shows that exposure to sodium chloride and magnesium chloride had a priming effect and seedling emergence was significantly increased in comparison to control. The beneficial effects of NaCl on seed germination is due to the uptake of Na⁺ and Cl^? ions by the seed, thus maintaining a water potential gradient allowing water uptake during seed germination.     

Symbiotic parameters,growth, nutrient accumulation,productivity and profitability as influenced by integrated nutrient management in lentil (Lens culinaris)

Field experiments evaluated the effects of integrated nutrient management on symbiotic parameters, growth, nutrient accumulation, productivity and profitability of lentil (Lens culinaris Medikus). Application of recommended dose of nutrients (RDN, 12.5 kg N ha^?1 + 40 kg P₂O₅ ha^?1) + 25 kg ZnSO₄ ha^?1 + seed inoculation with biofertilizers [Rhizobium + phosphate solubilizing bacteria (PSB) + plant growth promoting rhizobacteria (PGPR)] + 1.0 g ammonium molybdate kg^?1 seed recorded the highest number & dry weight of nodules, leghaemoglobin content, root & shoot dry weight, plant height, number of pods plant^?1 and 100-seed weight. The next best treatment was RDN + seed inoculation with biofertilizers + 1.0 g ammonium molybdate kg^?1 seed. On the basis of mean of three-year data, the treatment of RDN + 25 kg ZnSO₄ ha^?1 + seed inoculation with biofertilizers + 1.0 g ammonium molybdate kg^?1 seed proved the best in realizing the highest grain yield (34.0%), gross returns (34.0%) and net returns (54.8% higher over control). Nitrogen, phosphorus and potassium in the grains and straw were significantly improved where RDN was applied in combination with seed inoculation, basal application of ZnSO₄ and seed treatment with 1 g ammonium molybdate than their single applications.     

Role of carrier-based biofertilizer in reclamation of saline soil and wheat growth

Two plant growth promoting rhizobacteria (PGPR), Pseudomonas moraviensis and Bacillus cereus, were used as bioinoculants on wheat, applied alone and in combination. Ground maize straw and sugarcane husk were used as carriers. Experiment was conducted for two consecutive years (2010 and 2011) under axenic conditions in the greenhouse of Quaid-e-Azam University, Islamabad. Sodium chloride (NaCl) (150 mM) was applied with irrigated water after 7 and 14 days of seed germination. Measurements made 40 days after sowing (DAS) revealed that P. moraviensis and B. cereus have better survival efficiency (as evidenced by higher colony forming units (CFUs)) in the carriers. The substantial increase in CFU of both PGPR was also observed in the soil at 57 DAS. Coinoculation of PGPR with both the carrier materials significantly decreased electrical conductivity (EC) and Na⁺ content of soil over control. The N, P, K⁺, Ca⁺, and Mg⁺ contents were 30–40% higher in soil, and 30–45% higher in leaves. Coinoculation of PGPR with carriers significantly increased chlorophyll, protein, sugar, phytohormone contents, and antioxidant activities of leaves. The application of biofertilizers improved the yield of wheat by 15–25% over control. It is inferred that the carriers assisted PGPR for long-time survival, and the formulation was applicable in promoting crop production under salt stress.     

Physiological Responses of Leymus Chinensis to Long-Term Salt,Alkali and Mixed Salt-Alkali Stresses

The aim of this study was to evaluate the physiological responses of Leymus chinensis (Trin.) Tzvel exposed to long-term salt, salt-alkali, and alkali stress in order to elucidate how L. chinensis can survive under alkaline-sodic soils. L. chinensis (30 days after germination) were stressed with salt [SS; sodium chloride (NaCl)], mixed salt-alkali [MS; molar ratio of NaCl: sodium carbonate (Na₂CO₃) = 2:1] and alkali salt (AS; Na₂CO₃) at four different levels of sodium (Na⁺) concentration (0, 75, 150, and 300 mM) for 60 days. L. chinensis showed 100% survival rate at all treatments except 300 mM SS (33.3%) and AS (18.9%). The growth and physiological parameters of survival plants were measured. As anticipated, growth of L. chinensis was inhibited after stresses, which reflected in the decline of plant height, dry weight and tiller number following the increased Na⁺ concentration. The content of Na⁺, proline, and soluble sugar in L. chinensis increased with the increasing Na⁺ concentration, suggesting that L. chinensis need to accumulate inorganic and organic solutes for resisting osmotic stress induced by various salt stresses. These processes ensure the water balance that can provide a relative normal physiological environment for L. chinensis. Potassium (K⁺) content of L. chinensis kept at a relative lower level than control to ensure the normal physiological processes. Chlorophyll content of stressed plant increased slightly compared to control plants, which can produce more energy for L. chinensis resisting various stresses. The increased malondialdehyde (MDA) content of stressed plants showed the damage of various stresses. Among the three treatments (SS, MS, and AS), the injury extent for L. chinensis can be expressed by AS>SS>MS, and MS was the most complicated for the counterbalance effects of soil electrical conduction and pH.     

Use of cyanobacterial polysaccharides to promote shrub performances in desert soils: a potential approach for the restoration of desertified areas

The importance of cyanobacterial polysaccharides of biological soil crusts in sand surface stabilization and soil nutrient retention has been long acknowledged. However, the role of cyanobacterial polysaccharides as a source of nutrition to vascular plants in crusted areas is ignored. In this study, the chemical composition of the polysaccharide synthesized by Phormidium tenue and the effects of its presence on seed germination and seedling metabolism of the shrub Caragana korshinskii were investigated. The crude polysaccharide synthesized by P. tenue was composed of 15 % protein and 58 % carbohydrate and showed the presence of 12 different types of monosaccharides. The addition of the polysaccharide significantly (P?<?0.05) increased seed germination and metabolic activity of the seedling of the shrub C. korshinskii. The optimal concentration for vigor index, root length, root vigor, and total N and P contents was 10 mg/L polysaccharide; for the germination rate, nitrate reductase activity, carbohydrate content, chlorophyll, and Mg²⁺ content, the optimal was 60 mg/L polysaccharide, while for K⁺ and Ca²⁺ contents, photosynthetic efficiency and superoxide dismutase activity was 120 mg/L. The presence of the polysaccharide increased seed germination rate, ion uptake, and photosynthetic activity by affecting the electron transport chain and decreased oxidative damage by eliminating reactive oxygen species in C. korshinskii, thus promoting shrub performance in crusted desert areas.     

Evaluation of maturity and stability parameters of composts prepared from farm wastes

A composting experiment was carried out to study changes in physical [color, odor, temperature, organic matter (OM) loss], chemical [C:N ratio, water-soluble organic carbon (C_w):organic N (N_org) ratio, NH₄ ⁺-N and NO₃ ^?-N, humic acid (HA):fulvic acid (FA) ratio, humification index (HI) and cation-exchange capacity (CEC):total organic carbon (TOC) ratio)] and biological [seed germination index (GI)] parameters to assess compost maturity and stability over a period of 150 days. Five composts were prepared using a mixture of different farm wastes with or without enrichment of N, rock phosphate (RP) and microorganism (MO) inoculation. All the composts appeared to change to a granular and dark grey color without foul odor, and attained a constant temperature with no measurable changes (ambient level) at 120 days of composting. Correlation analysis showed that the optimal values of the selected parameters for our experimental conditions are as follows: organic matter loss > 42%, C:N ratio < 15, HA:FA ratio > 1.9, HI > 30%, CEC:TOC ratio > 1.7 and C_w:N_org ratio < 0.55. Composts enriched with N + RP or N + RP + MO matured at 150 and 120 days, respectively, whereas composts without any enrichment or enrichment with N or RP + MO did not mature even at 150 days of composting.     

Silicon and Potassium Nutrition Enhances Salt Adaptation Capability of Sunflower by Improving Plant Water Status and Membrane Stability

The relationships between salinity and mineral nutrition are extremely complex and may change depending on many factors in soil-plant system. We investigated the contribution of silicon (Si at 50 mg kg^?1 soil) and potassium (K at 40 and 60 mg K₂O kg^?1 soil) to improve salt tolerance in sunflower grown with 100 mM sodium chloride (NaCl). The experimental design was factorial based on a completely randomized design with five replications. Added NaCl increased sodium ion (Na⁺) accumulation by 966 percent in shoots and 1200 percent in roots but reduced shoot potassium ion (K⁺) concentration by 49 percent, root K⁺ 51 percent, and shoot K⁺/Na⁺ ratio 95 percent. However, Si and K application effectively reduced Na⁺ accumulation and increased K⁺ concentration and K⁺:Na⁺ ratio, with a significant improvement in plant growth and yield. Among all treatments, greater alleviative effects of Si and K were observed for 50 mg Si + 60 mg K₂O kg^?1 soil, which decreased shoot Na⁺ concentration by 67 percent, root Na⁺ 18 percent, and shoot Na⁺/root Na⁺ ratio 60 percent and increased shoot K⁺ by 198 percent, shoot K⁺/Na⁺ ratio 812 percent, membrane stability index (MSI) 35 percent, relative water content (RWC) 26 percent, and seed weight head^?1 86 percent compared to salt-stressed plants without supplemental Si and K. Most of the plant growth parameters were negatively correlated with Na⁺ accumulation but positively correlated with K⁺ and K⁺/Na⁺ ratio. This study suggests that Si and K mediated reduction in Na⁺ accumulation, and increase in K⁺ concentration, K⁺/Na⁺ ratio, RWC, and MSI are the main factors contributing to improved adaptation capability of sunflower to NaCl stress.     

Rhizosphere effects of maize hybrids and N forms on Cd bioavailability in a limed soil

Replacing new corn genotypes in agricultural practices requires adequate information on the reaction of the selected hybrids to Cd uptake in Cd-polluted soil and an understanding of interactions with N fertilizers. A 2 × 2 × 3 factorial pot experiment with limed soil (pH 8), two maize (Zea mays) hybrids (Pioneer cultivar yellow and Pioneer cultivar white), two N fertilization forms (NH₄ ⁺ and NO₃ ^?) and three Cd exposures (0, 2 and 5 mg kg^?1 soil) was conducted under greenhouse conditions. Shoot dry mass increased significantly with NH₄ ⁺ nutrition compared with NO₃ ^? nutrition in both maize hybrids, with greater negative influence of Cd application combined with NH₄ ⁺ nutrition. The yellow cultivar had significantly greater shoot dry mass and lower Cd uptake than the white cultivar. Both hybrids exhibited similar N uptake in shoots and roots, with the exception of yellow cultivar with NH₄ ⁺ nutrition without Cd application. NO₃ ^? nutrition always decreased Cd uptake in both cultivars compared with NH₄ ⁺ nutrition. The N balance (mean across cultivars and Cd supply) after harvest showed most N uptake with NH₄ ⁺ nutrition (63.4%) and N_min remains in the soil with NO₃ ^? nutrition (48.7%). Soil pH decreased more with NH₄ ⁺ (?0.95 pH units) than NO₃ ^? nutrition (?0.21).     

Effects of Salinity and Nitrogen on Growth,Contents of Pigments,and Ion Accumulation of a Euhalophyte Suaeda Salsa in an Intertidal Zone and on Saline Inland

The different responses of two populations of Suaeda salsa (Linn.) Pall. (saline seepweed) from an intertidal zone and a saline inland zone to salinity [1 or 500 mM sodium chloride (NaCl)] and nitrogen [N; 0.05, 1, or 10 mM nitrate (NO₃ ^?)‐N] were investigated. Greater NO₃ ^?‐N supply (10 mM) increased shoot dry weight for the two populations of S. salsa, especially for S. salsa from the saline inland zone. Greater NO₃ ^?‐N supply (10 mM) increased the concentrations of chlorophyll and carotenoid in leaves and the NO₃ ^? and potassium (K⁺) concentrations in shoots for both populations. Greater NO₃ ^?‐N supply (10 mM) increased shoot Na⁺ in S. salsa from the intertidal zone. In conclusion, S. salsa from the saline inland zone is more responsive to NO₃ ^?‐N supply than the intertidal population. Greater NO₃ ^?‐N supply can help the species, especially the intertidal population, to grow and to mediate ion homeostasis under high salinity.     

Greenhouse gases emission,soil organic carbon and wheat yield as affected by tillage systems and nitrogen management practices

Agricultural activities are responsible for greenhouse gases (GHGs) emission in the environment. Strategies are required to enhance the soil organic carbon (SOC) and nitrogen (N) sequestration to adapt and mitigate the climate change. We investigated GHGs emission, SOC and N enhancement under conventional tillage (CT) and zero tillage (ZT) with N management in wheat (Triticum aestivum L.). Seasonal carbon dioxide (CO₂) emission and global warming potential (GWP) reduced for ZT treatments over CT without residues and 100% of required N with a blanket split application (CT – R + 100N). The ZT with 5 t ha^?1 maize (Zea mays L.) residues retention and 75% of required N and GreenSeeker^TM (GS)-aided N management (ZT + R + 75N + GS) reduced yield-scaled GHGs emission and increased total organic carbon (C) stock over CT – R + 100N. However, nitrous oxide (N₂O) emission was lower in CT. The GS-based N management saved 26–35 kg N ha^?1 in different tillage systems in both years over blanket application with higher N uptake and associated reduction in N₂O emission. The study recommends that ZT with residues retention and GS-based N management can minimize the GHGs emission and improve the SOC.     

Efficacy of starter N fertilizer and rhizobia inoculant in dry pea (Pisum sativum Linn.) production in a semi-arid temperate environment

ABSTRACT

Uncertainties exist about the importance of rhizobia inoculant and starter nitrogen (N) application in dry pea (Pisum sativum L.) production. Three field experiments were conducted to evaluate how rhizobia inoculant and starter N fertilizer affect pea seed yield and protein concentration in a semi-arid environment in central Montana. Commercial rhizobia inoculant was mixed with seed prior to planting at the manufacturer’s recommended rate. Starter N fertilizers were applied into the same furrow as seed at 0, 22, 44 and 88 kg ha^?1 as urea, slow-release polymer-coated N fertilizer (ESN), and a combination of both. The application of rhizobia inoculant had no or a very small beneficial effect on pea yield in lands with a previous history of peas. In a land without pea history, application of rhizobia increased pea seed yield by 16%. The positive effect of starter N was only pronounced when initial soil N was low (≤ 10 kg ha^?1 nitrate-nitrogen), which increased net return by up to US$ 42 ha^?1. In this condition, application of slow-release N outperformed urea. However, application of starter N (especially with urea) had a negative effect on pea establishment, vigor and seed yield when soil initial N was high (≥ 44 kg ha^?1 NO₃-N). The results indicate that the rate, placement and form of the starter N must be optimized to benefit pea yield and protein without detrimental effects on germination and nodulation. Moreover, application of starter N must be guided by the soil nitrate content.     

Individual and additive effects of Na+ and Cl− ions on rice under salinity stress

This study was attempted to assess the extent of toxicity contributed by Na⁺ and/or Cl^? ions individually, besides their possible additive effects under NaCl using physiological and biochemical parameters. Despite the fact that most annual plants accumulate both Na⁺ and Cl^? under saline conditions and each ion deserves equal considerations, most research has been focused on Na⁺ toxicity. Consequently, Cl^? toxicity mechanisms including its accumulation/exclusion in plants are poorly understood. To address these issues, effects of equimolar (100 mM) concentrations of Na⁺, Cl^? and NaCl (EC ≈ 10 dS m^?1) were studied on 15-day-old seedlings of two rice cultivars, Panvel-3 (tolerant) and Sahyadri-3 (sensitive), using in vitro cultures. All three treatments induced substantial reductions in germination rate and plant growth with greater impacts under NaCl than Na⁺ and Cl^? separately. Apparently, salt tolerance of Panvel-3 was due to its ability to exclude Na⁺ and Cl^? from its shoots and maintaining low (<1.0) Na⁺/K⁺ ratios. Panvel-3 exhibited better vigour and membrane stability indices coupled with lower reactive oxygen species and lipid peroxidation levels, besides stimulated synthesis of proline, glycine betaine and ascorbic acid. Overall, the magnitude of toxicity was observed in NaCl > Na⁺ > Cl^? manner. Though Cl^? was relatively less toxic than its countercation, its effect cannot be totally diminished.     

Variability of the Effects of Salinity on Reproductive Capacity of Arabidopsis Thaliana

Abstract

For this study, the diversity of some effects of salinity on rosette growth, seed production, and seed viability in Arabidopsis thaliana was explored. Plants from 5 accessions (“ecotypes”) were grown on a sand-peat mixture irrigated with nutritive medium. At the emergence of inflorescence axis, 35 mM NaCl was added to the solution. Several morphological parameters of the rosette were measured at the beginning of silique opening, irrigation was interrupted and the substrate was allowed to dry. The siliques and the mature seeds were harvested, and assayed for K⁺, Na⁺ and Cl^?. Seeds were sown on pure water and germination kinetics were determined. There was a large inter-ecotype variability of the effect of salt on the rosette growth and on all factors contribution to reproduction (number of inflorescence axes, number of flower per axis, flower fertility, and seed viability). Among the five ecotypes, those with highest levels of Na⁺ and Cl^? in the silique valves produced the less viable seeds. This comparison, (i) suggests that salt accumulation in the former organs has detrimental effect on seed maturation, and (ii) indicates that there is a natural variability for control of ion transport to fruits in A. thaliana.     

Growth response of the salt-sensitive and the salt-tolerant sugarcane genotypes to potassium nutrition under salt stress

Adequate regulation of mineral nutrients plays a fundamental role in sustaining crop productivity and quality under salt stress. We investigated the ameliorative role of potassium (K as K₂SO₄) in overcoming the detrimental effects of sodium chloride (NaCl) on sugarcane genotypes differing in salt tolerance. Four levels of NaCl (0, 100, 130 and 160 mM) were imposed in triplicate on plants grown in gravel by supplying 0 and 3 mM K. The results revealed that application of NaCl significantly (p ≤ 0.05) increased sodium (Na⁺) but decreased K⁺ concentrations in shoots and roots of both genotypes with a resultant decrease in K⁺/Na⁺ ratios. Physical growth parameters and juice quality were also markedly reduced with increasing NaCl concentrations compared with controls. However, addition of K alleviated the deleterious effects of NaCl and improved plant growth under salt stress. Cane yield and yield attributes of both genotypes were significantly (p ≤ 0.05) higher where K was added. Juice quality was also significantly (p ≤ 0.05) improved with the application of K at various NaCl levels. The results suggested that added K interfered with Na⁺, reduced its uptake and accumulation in plant tissues and consequently improved plant growth and juice quality in sugarcane.     

Effect of nitrogen application on seed yield,pod and seed characteristics of okra

Four okra cultivars [Abelmoschus esculentus (L.) Moench] were cultivated for two growing periods at nitrogen (N) application rates of 150, 300 and 450 mg N L^?1. There was no effect of N on pod size (length and diameter) or on the number of seeds per pod and seed size (mean 1000 seed weight), all these characteristics of which related to the genotype. High N application (450 mg N L^?1), increased the seed yield of the cultivar with the lowest flower induction (Boyiatiou), but only in experiment 2. In Veloudo, seed yield was highest at 300 mg N L^?1, whereas in Pylaias and Clemson 450 mg N L^?1 reduced seed yield. In all cultivars, seeds produced at an N rate of 450 mg N L^?1 exhibited a significantly higher percent germination N, possibly by reducing the incidence of seed hardness.     

Promoting deep-sowing germinability of corn (Zea mays) by seed soaking with gibberellic acid

The effects of seed soaking with gibberellic acid (GA₃) on germinability of conventional corn variety ‘Nongda 108’ and super sweet corn variety ‘Chaotian 3’ were investigated under deep-sowing condition. GA₃ soaking significantly improved seed germination and mesocotyl elongation of both varieties under 10 or 6 cm sowing depth. The most significant promotion occurred at 0.175 g L^?1 GA₃ in ‘Nongda 108’ and 0.035 g L^?1 GA₃ in ‘Chaotian 3’. To further illustrate the physiological explanations, seed respiration was estimated from dehydrogenase activity test and oxygen-sensing test. Dehydrogenase activities of both varieties were dramatically promoted after GA₃ soaking. Compared with water soaking, the dehydrogenase activity in 0.175 g L^?1 GA₃-soaked seeds of ‘Nongda 108’ and 0.035 g L^?1 GA₃-soaked ones of ‘Chaotian 3’ was increased by 15.4% and 78.8%, respectively. Oxygen-sensing test showed that increased metabolism time (IMT) critical oxygen pressure (COP) and relative germination time (RGT) were decreased while oxygen metabolism rate (OMR) and relative germination rate (RGR) were increased in GA₃-soaked seeds, suggesting that exogenous GA-accelerated seed respiration. Our results suggested that seed soaking with exogenous GA₃ was a simple and practicable method to improve deep-sowing tolerance during corn seed germination, and the significant promotions were attributed to vigorous respiratory metabolism.     

Productivity,profitability and sustainability of rain-fed chickpea under inorganic and biofertilization in foothills of north-west Himalayas

A 4-year (2008–2009 to 2011–2012) study was conducted on the effect of mineral phosphorus (P) + sulphur (S) and biofertilizers on rain-fed chickpea (Cicer arietinum L.) at the Punjab Agricultural University’s Research Station, Ballowal Saunkhri, India. The experiment comprised of five combinations of P and S, viz. control (P₀S₀), no P + 10 kg S ha^?1 (P₀S₁₀), 15 kg P + 10 kg S ha^?1 (P₁₅S₁₀), no P + 20 kg S ha^?1 (P₀S₂₀) and 30 kg P + 20 kg S ha^?1 (P₃₀S₂₀); and three seed inoculation levels, viz. control, Rhizobium and phosphate-solubilizing bacteria (PSB), were laid out in randomized complete block design. Combined application of P + S resulted in improved growth, nodulation, yield attributes and yield. The increase in seed yield over control due to P + S ranged from 11.8% to 17.7%. Seed inoculation with Rhizobium recorded the highest growth, nodulation, yield attributes and yield of chickpea and was statistically at par with PSB and significantly better than no inoculation. Highest benefit/cost ratio (B:C, 2.19) was obtained in P₃₀S₂₀. In view of environmental pollution and high costs of chemical fertilizers, biofertilizers alone or in combination may help to achieve sustainable and ecological agricultural production.     

Influence of nitrogen fertilizer forms and crop straw biochars on soil exchange properties and maize growth on an acidic Ultisol

Effects of repeated application of urea (UN) and calcium nitrate (CN) singly and together with crop straw biochars on soil acidity and maize growth were investigated with greenhouse pot experiments for two consecutive seasons. Canola straw biochar (CB), peanut straw biochar (PB) and wheat straw biochar (WB) were applied at 1% of dried soil weight in the first season. N fertilizers were applied at 200 mg N kg^?1. In UN treatments, an initial rise in pH was subjected to proton consumption through urea hydrolysis, afterwards nitrification of NH₄⁺ caused drastic reductions in pH as single UN had soil pH of 3.70, even lower than control (4.27) after the 2nd crop season. Post-harvest soil analyses indicated that soil pH, soil exchangeable acidity, NH₄⁺, NO₃^? and total base cations showed highly significant variation under N and biochar types (P < 0.05). Articulated growth of plants under combined application with biochars was expressed by 22.7%, 22.5%, and 35.7% higher root and 25.6%, 23.8%, and 35.9% higher shoot biomass by CB, PB and WB combined with CN over UN, respectively. Therefore, CN combined with biochars is a better choice to correct soil acidity and improve maize growth than UN combined with biochars.