Non-leguminous Crops Research Articles

Microbiological mechanism of hydrogen fertilizer effect in soil.

For a long time, intercropping and rotation of leguminous with non-leguminous crops is widely used to reduce the application of nitrogen fertilizer and increase yield in agroecosystems. At present, most researchers considered that this management measure is helpful for reducing fertilizer consumption and increasing its efficiency, as it can improve nutrient supply of legumestonon-legumes, the spatial nutrient utilization efficiency by enhancing soil spatial heterogeneity, and improve soil structure and disease resistance. However, current theories cannot fully explain the positive effect of crop rotation and inter-cropping systems involving legumes. A large amount of hydrogen (H2) can be produced as an obligatory by-product of nitrogenase responsible for nitrogen (N2) fixation in the root nodules of leguminous plants. Despite of substantial amounts of H2 enriched in the rhizosphere of legumes, only a minor proportion of H2 is found to leak to soil surface. Increasing evidence showed that most H2 released in soil is immediately depleted in the surrounding of N2-fixing nodules by H2-oxidizing bacteria (HOB) thriving in soil. HOB can use H2 as an electron donor to assimilate and fix CO2 through redox reactions to synthesize cellular substances and consequently promote plant growth. To date, however, little is known about the biological mechanism and ecological process behind the "hydrogen fertilizer effect". Therefore, we review the H2-induced plant growth-promoting effects and its microbiological mechanisms. Our aims were to explore a new way for enhancing agroecosystem production, and to provide scientific basis for future utilization of H2 in agricultural production practices.

Characterization of Rhizobia Isolated from Tigray Soil and Assessment of Their Effect on Germination and Seedling Vigor of Wheat and Field Pea

Nowadays, the inoculation of plant growth-promoting rhizobia in leguminous and nonleguminous crops is given great emphasis as it improves germination and seedling vigor, resulting in increased yields. In this study, 32 rhizobia isolates were obtained from five different sampling sites in Tigray, Ethiopia. Based on morphological, biochemical, and confirmatory tests, including sugar fermentation, the isolates were identified as belonging to the rhizobia genera. In vitro assessment of plant growth-promoting properties revealed that all isolates produced indole-acetic-acid, ammonia, and solubilized phosphate, except TA8, which did not solubilize phosphate. Only 3 isolates (TA1, TA2, and TA8) produced hydrogen cyanide, so they can be used as biocontrol agents. Nineteen isolates showed a growth reduction activity against Fusarium oxysporum, with a percent inhibition range of 34.2%–65.8%. All isolates tolerated a pH range of 4.0–9.0. The isolates showed growth variations in various temperatures and salt concentrations. A few isolates were tolerant up to 45°C temperature and 6% (w/v) CaCl2 and NaCl concentrations. Inoculation of the isolates to wheat seeds increased seed germination, seedling shoot/root length, and seedling vigor index compared to the positive and negative controls. Isolates KO3, KO4, ME3, and TA5 increased seed germination by 4%. KO1 (11.60 cm) and TA7 (11.70 cm) showed a significantly enhanced shoot length, and ME3 showed a maximum root length (13.90 cm). SH1, KO2, and the positive control showed a significant (P≤0.05) increase in pea seed germination (by 20%) compared to the negative control. The positive control had the longest field pea shoot (5.70 cm), and isolate TA9 had the longest field pea root (5.32 cm) compared to the negative control. Generally, the wheat and field pea seedlings responded differently to the inoculation of different isolates. This study shows that Tigray soils harbor a variety of rhizobia species, which can be used as plant growth-promoting and biocontrol agents.

A genome-scale metabolic reconstruction of soybean and Bradyrhizobium diazoefficiens reveals the cost-benefit of nitrogen fixation.

Nitrogen-fixing symbioses allow legumes to thrive in nitrogen-poor soils at the cost of diverting some photoassimilate to their microsymbionts. Effort is being made to bioengineer nitrogen fixation into nonleguminous crops. This requires a quantitative understanding of its energetic costs and the links between metabolic variations and symbiotic efficiency. A whole-plant metabolic model for soybean (Glycine max) with its associated microsymbiont Bradyrhizobium diazoefficiens was developed and applied to predict the cost-benefit of nitrogen fixation with varying soil nitrogen availability. The model predicted a nitrogen-fixation cost of c. 4.13 g C g-1 N, which when implemented into a crop scale model, translated to a grain yield reduction of 27% compared with a non-nodulating plant receiving its nitrogen from the soil. Considering the lower nitrogen content of cereals, the yield cost to a hypothetical N-fixing cereal is predicted to be less than half that of soybean. Soybean growth was predicted to be c. 5% greater when the nodule nitrogen export products were amides versus ureides. This is the first metabolic reconstruction in a tropical crop species that simulates the entire plant and nodule metabolism. Going forward, this model will serve as a tool to investigate carbon use efficiency and key mechanisms within N-fixing symbiosis in a tropical species forming determinate nodules.

Genome-Wide Identification and Characterization of the Soybean Snf2 Gene Family and Expression Response to Rhizobia.

Sucrose nonfermenting 2 (Snf2) family proteins are the core component of chromatin remodeling complexes that can alter chromatin structure and nucleosome position by utilizing the energy of ATP, playing a vital role in transcription regulation, DNA replication, and DNA damage repair. Snf2 family proteins have been characterized in various species including plants, and they have been found to regulate development and stress responses in Arabidopsis. Soybean (Glycine max) is an important food and economic crop worldwide, unlike other non-leguminous crops, soybeans can form a symbiotic relationship with rhizobia for biological nitrogen fixation. However, little is known about Snf2 family proteins in soybean. In this study, we identified 66 Snf2 family genes in soybean that could be classified into six groups like Arabidopsis, unevenly distributed on 20 soybean chromosomes. Phylogenetic analysis with Arabidopsis revealed that these 66 Snf2 family genes could be divided into 18 subfamilies. Collinear analysis showed that segmental duplication was the main mechanism for expansion of Snf2 genes rather than tandem repeats. Further evolutionary analysis indicated that the duplicated gene pairs had undergone purifying selection. All Snf2 proteins contained seven domains, and each Snf2 protein had at least one SNF2_N domain and one Helicase_C domain. Promoter analysis revealed that most Snf2 genes had cis-elements associated with jasmonic acid, abscisic acid, and nodule specificity in their promoter regions. Microarray data and real-time quantitative PCR (qPCR) analysis revealed that the expression profiles of most Snf2 family genes were detected in both root and nodule tissues, and some of them were found to be significantly downregulated after rhizobial infection. In this study, we conducted a comprehensive analysis of the soybean Snf2 family genes and demonstrated their responsiveness to Rhizobia infection. This provides insight into the potential roles of Snf2 family genes in soybean symbiotic nodulation.

The Influence of Lablab Purpureus Growth on Nitrogen Availability and Mineral Composition Concentration in Nutrient Poor Savanna Soils

Low soil fertility in savanna soils has been linked to low crop yields, with nitrogen being the most limiting factor in crop yield. Soil used in this pot experiment was obtained from Motshephiri village with low total N, low NO3− and high NH4+. A pot experiment was conducted in a greenhouse laid in a Randomized Complete Block Design with four treatments (1) control, (2) Bradyrhizobium japonicum inoculant, (3) superphosphate and (4) Bradyrhizobium japonicum inoculant + superphosphate). The superphosphate was applied at three different levels (45, 60 and 75 kg/ha). Lablab was cultivated in each treatment and the results of the study indicated that lablab growth significantly increased total N and NO3−, and reduced concentration NH4+ relative to the original soil herein referred to as pre-lablab growth. However, the N forms (total N, NO3− and NH4+) did not differ significantly amongst different levels of superphosphate with or without Bradyrhizobium japonicum inoculant. Lablab growth, proved to have a significant impact on both the soil macro (P, K, Ca, Mg, and Na) and micronutrient level (Fe, Mn, Cu, B and Cl) with the exception of Zn. This study suggests that lablab’s ability to rapidly boost soil N content, overall soil fertility in a short period of time without the use of superphosphate fertilizers or Bradyrhizobium japonicum inoculants makes it ideal for intercropping or rotating with non-leguminous crops that have a short growing season.

Intercropping with Pigeonpea (Cajanus cajan L. Millsp.): An Assessment of Its Influence on the Assemblage of Pollinators and Yield of Neighbouring Non-Leguminous Crops.

Intercropping is practiced in modern intensive agriculture considering many benefits, including additive crop yield. However, it may have competitive or facilitative interactions between pollinator-dependant crops. Here, we investigated the reproductive aspects of pigeonpea (Cajanus cajan). We assessed the influence of blooming pigeonpea on pollinator's assemblage and the yield of neighbouring non-leguminous crops (e.g., coriander, mustard). For these, we recorded floral visitors and the yield of the targeted crops from two types of fields-closely situated and distantly situated concerning pigeonpea plantation. Pigeonpea is autogamous, but pollinator's visits enhance fruit and seed sets. Bright, nectariferous flowers emitted several volatile organic compounds and were visited by numerous insect species. The prime pollinators of pigeonpea are carpenter bees and leafcutter bees. In contrast, halictidae, honeybees and stingless bees mainly pollinate the co-blooming non-leguminous crops (coriander and mustard). The richness and abundance of pollinators on these co-blooming crops remain similar in closely situated and distantly situated fields. As a result, the yield of the neighbouring crops is not significantly influenced by the blooming pigeonpea. Therefore, it can be concluded that planting pigeonpea in ridges of agricultural fields will be an additional agricultural output without affecting the assemblage of pollinators and yields of neighbouring co-blooming crops.

Exploring a rhizobium to fix nitrogen in non-leguminous plants by using a tumor-formation root pathogen

Over 110 million tons of nitrogen fertilizer every year is used for crop production. Scientists have dreamed of enabling rhizobial nitrogen fixation in non-leguminous crops to mitigate the increasing demand for nitrogen fertilizer. However, despite decades of research, rhizobial nitrogen fixation in non-host plants has not been demonstrated. Here, we reported that an N-fixing rhizobium and a clubroot pathogen Plasmodiophora brassicae exhibited a synergistic effect on fixing nitrogen in cruciferous plants. Rhizobia were found to invade P. brassicae-infected rapeseed (Brassica napus) roots in the field. The colonization of rhizobium on rapeseed roots was confirmed by co-inoculating Mesorhizobium huakuii with P. brassicae under controlled laboratory conditions. M. huakuii infection could alleviate clubroot symptoms and promote the growth of diseased rapeseeds. M. huakuii could fix nitrogen in P. brassicae-infected plants based on the results of 15N isotope dilution tests. The expression of homologs of legume genes required for symbiosis and early-nodulin genes was significantly upregulated in Arabidopsis during early infection by P. brassicae. More importantly, M. huakuii could even fix nitrogen in P. brassicae-resistant rapeseed cultivar and promote plant growth when co-inoculated with P. brassicae. Our findings provide a new avenue to understand the interaction of rhizobia with non-host plants, stimulate the exploration of fixing nitrogen in non-leguminous plants by nitrogen-fixing rhizobia, and develop a strategy for both disease control and nitrogen fixation on non-host crops.

Role of soybean (Glycine max) on the fruiting enhancement of chilli (Capsicum annuum) under intercropping system

Intercropping is an agricultural approach in which two or more crop species, cohabit for a period of time. Intercropping is viewed as a sustainable, environmentally friendly and profitable cropping strategy by its proponents. The field work was carried out in the agricultural land of Arni University, Distt. Kangra of Himachal Pradesh during the months of June-August 2021. The main objective of present study was to make people aware about intercropping system so that they can adopt these agricultural practices and apply them for good crop production. In the current study, intercropping leguminous plant Glycine max was grown with non-leguminous vegetable crop Capsicum annuum in order to achieve higher productivity of non-leguminous crop plants. Different morphological parameters including plant height, leaf length, number of leaves, leaf breadth and fruit size were measured and recorded weekly. Findings of present investigation indicated that plant height (46.89±0.01 cm), leaf length (7.56±0.06 cm), leaf number (33.66±0.33 cm), leaf breadth (4.47±0.03 cm) and fruit size were significantly increased and it ensured that the leguminous crop soybean (Glycine max) had a favourable impact on non-leguminous vegetable crop (Capsicum annuum) production. Future explore in this field may help farmers in order to improve yield stability and to minimize risk of crop failure.

Guar (Cyamopsis tetragonoloba [L.] Taub.) response to organic and inorganic nitrogen sources during early seedling growth

Guar (Cyamopsis tetragonoloba [L.] Taub.), a legume, has gained its industrial importance due to galactomannan gum in its seed endosperm. As a legume guar Rhizobium nodulation is usually inadequate. Thus, it does not fix nitrogen sufficiently in the soil. Guar seeds were germinated under five concentrations each of organic {Bovine Serum Albumin (BSA)}, inorganic {Ca(NO3)2} and combined {(BSA + Ca(NO3)2} nitrogen sources in order to analyze the morphological, anatomical, and protein concentration changes due to different concentrations of varying nitrogen sources. Low nitrogen concentration in modified Hoagland’s solution in absence of preexisting nitrogen in the supporting solution (coco peat) showed significantly reduced morphological and anatomical characteristics and total protein concentration. On the other hand, the combination of organic and inorganic nitrogen sources showed greater effect on morphological, anatomical characters, and total protein concentration than individual treatments and control. At 16.1 mM nitrogen [given through combined treatment of 0.075 g/dL BSA + 0.095 g/dL Ca (NO3)2] metaxylem number (MXN), percent of stele that is metaxylem (percSisMX) and total protein concentration (TPC) were nearly equal or higher than the control. These parameters are positively correlated with each other which indicates that MXN, percSisMX and TPC contribute to relieve guar plant from nitrogen stress by more inflow of water and nutrients. Results show despite being a leguminous crop guar behaves as non-leguminous crop toward nitrogen and is affected by nitrogen stress during germination.

Integrating Crop-Livestock System Practices in Forage and Grain-Based Rotations in Northern Germany: Potentials for Soil Carbon Sequestration

Integrating leys, cover crops, and animal manures constitute promising avenues to reach annual soil organic carbon changes (ΔSOC) >0.4% in forage and grain-based crop rotations, rates required to offset the increasing C emissions from fossil fuels (“4 per mille” initiative). How these practices and rotations perform in reaching this aim was object of analysis in this paper. Five cropping systems (CS), including three three-year forage and grain-based crop rotations containing annual grass-clover leys (FR and MR) or cover crops (GR), and two contrasting controls (continuous silage maize (CM), and permanent grassland (PG)) were compared for their impact on SOC stocks over eight years (2010–2018). The CS were unfertilized (N0) or fertilized using cattle slurry (N1) at a rate of 240 kg N ha−1 yr−1 applied in the non-leguminous crops. The ΔSOC of the top 30 cm soil layer and the annual carbon inputs (Cin) from slurry applications and plant residues were estimated, their relationship established, and the slurry-induced C retention coefficient was determined. The FR and MR SOC stocks remained stable at N1, while the GR and CM SOC decreased over time by tendency even at N1. Only the PG reached ΔSOC >0.4%. Differences in ΔSOC between CS and N rates were highly associated with the system-specific increase in belowground Cin, induced by slurry applications. Slurry-induced C retention coefficients differed strongly between CS: CM (3%) followed by GR (12%), and by FR and MR (20–15%), and lastly by PG (24%). Promoting belowground carbon inputs was identified as an efficient way to reach significant increases in ΔSOC. We conclude that a ley in only one out of three years is not sufficient to significantly increase SOC stocks in arable crop rotations of the study region.

Potential of Coupling Heavy Metal (HM) Phytoremediation by Bioenergy Plants and Their Associated HM-Adapted Rhizosphere Microbiota (Arbuscular Mycorrhizal Fungi and Plant Growth Promoting Microbes) for Bioenergy Production

There is growing concern for the contamination of our soils and waters worldwide with heavy metals (HMs), as a result of indiscriminate use of agrochemicals for feeding growing population which require optimal use of resources and sustainable agricultural strategies. This can be simultaneously achieved by using microbes as bio-fertilizers, bio-protectants, and bio-stimulants, and suitable phytoremediation- plant capable of removing heavy metals contaminants from contaminated sites. There is a growing need to adopt such environmentally safe, attractive, and economical techniques that can remove most HMs contaminants as well as yield high biomass for bioenergy production. Phytoremediation and the microbes associated with the roots and inhabiting rhizospheres of the plants used for this purpose, has emerged as an alternative strategy. This article reviews the principles and application of this strategy, and provides an overview of the use of fast growing, non-food bioenergy plants, like Vetiver grass and industrial hemp, and their root-associated microbiota such as Arbuscular Mycorrhizal Fungi (AMF), Mycorrhiza Helping Bacteria (MHB), and Plant–Growth–Promoting-Rhizobia (PGPR) that can both tolerate and immobilize HMs in the roots, i.e. sequestrate contaminant HMs thereby protecting plants from metal toxicity. This mini-review also focuses on other phytoextraction strategies involving rhizosphere microbes, such as (1) inoculating plants used for phytoremediation of HMs contaminated soil and water with rhizobial microflora, and (2) managing their population in the rhizospheres by using a consortium of site specific AMF, PGPR, and MHB, and N-fixing rhizobia as biofertilizers to Phyto-remediate derelict contaminated sites. Various crop management strategies such as Crop Sequencing and Intercropping or Co-cropping of, for example, mycorrhizal and non-mycorrhizal crops, or leguminous and non-leguminous crops, etc., can be employed for improved plant growth. Another possible strategy to exploit soil microbes is to employ pre-cropping with mycotrophic crops to exploit AMF for mycorrhizo-remediation strategy.

Assessing Yield Response and Relationship of Soil Boron Fractions with Its Accumulation in Sorghum and Cowpea under Boron Fertilization in Different Soil Series

Boron (B) is an essential micronutrient in the growth of reproductive plant parts. Its deficiency and/or toxicity are widespread in arid and semi-arid soils with low clay contents. This study was planned to determine the response of sorghum (Sorghum bicolor L., non-leguminous crop) and cowpea (Vigna sinensis L., leguminous crop) to boron (0, 2, 4, and 16 µg g−1) on four distinct soil series from Punjab, Pakistan i.e., Udic Haplustalf (Pindorian region), Typic Torrifluvent (Shahdra region), Halic Camborthid (Khurianwala region), and Udic Haplustalf (Gujranwala region). Overall, there was a significant difference (p < 0.05) in yield between the sorghum (3.8 to 5.5 g pot−1 of 5 kg dry soil) and cowpea (0.2 to 3.2 g pot−1 of 5 kg dry soil) in response to B application. The highest yield was observed in both sorghum and cowpea either in control or at 2 µg g−1 B application in all four soils. Cowpea showed the same yield trend in all four soils (i.e., an increase in yield at 2 µg g−1 B application, followed by a significant decrease at the higher B levels). In contrast, sorghum exhibited greater variability of response on different soils; Udic Haplustalf (Pindorian region) produced the greatest yield at low levels of B application. However, Halic Camborthid produced its lowest yield at that level. Boron concentration in shoots increased with the levels of B application, particularly in sorghum. In cowpea, the plant growth was extremely retarded—and most of the plants died at higher levels of B application even if a lower concentration of B was measured within the shoot. Hot water-extractable B was the most available fraction for cowpea (R2 = 0.96), whereas the easily exchangeable B was most available for sorghum (R2 = 0.90). Overall, these results have implications for micronutrient uptake for both leguminous and non-leguminous crops.

Phosphorus Nutrition and Growth of Cotton Plants Inoculated With Growth-Promoting Bacteria Under Low Phosphate Availability

The low availability of phosphorus (P) in the soil drastically limits the world productivity of crops such as cotton. In order to contribute sustainably to the solution of this problem, the current study aimed to evaluate the capacity of phosphate-solubilising bacteria to improve plant growth and its relationship with physiological parameters, as well as the shoot P content in cotton plants in a soil with low P availability amended with rock phosphate. The results showed that, of the six plant growth-promoting bacteria strains evaluated under greenhouse conditions, the Rhizobium strain B02 significantly promoted growth, shoot P content and photosynthetic rate. This strain also improved the transpiration rate and the relative content of chlorophyll but without significant differences. Remarkably, Rhizobium sp. B02 had a more significant effect on plant growth compared to the P nutrition. Furthermore, the effect of its inoculation was more pronounced on the roots' growth compared to the shoot. Finally, application of Rhizobium strain B02 showed the capacity to optimize the use of low-solubility fertilizer as the rock phosphate. These findings could be associated with the metabolic activities of plant growth promotion exhibited by phosphate-solubilising strains, such as phosphate solubilisation, production of indole compounds and siderophores synthesis. In conclusion, this research provides evidence of the biotechnological potential of the Rhizobium genus as phosphate-solubilising bacteria with multiple plant growth-promoting activities capable of improving the plant growth and phosphate nutrition of non-leguminous crops such as cotton in soil with low P availability amended with rock phosphate.

30 years of free-air carbon dioxide enrichment (FACE): What have we learned about future crop productivity and its potential for adaptation?

Free-air CO2 enrichment (FACE) allows open-air elevation of [CO2 ] without altering the microclimate. Its scale uniquely supports simultaneous study from physiology and yield to soil processes and disease. In 2005 we summarized results of then 28 published observations by meta-analysis. Subsequent studies have combined FACE with temperature, drought, ozone, and nitrogen treatments. Here, we summarize the results of now almost 250 observations, spanning 14 sites and five continents. Across 186 independent studies of 18 C3 crops, elevation of [CO2 ] by ca. 200ppm caused a ca. 18% increase in yield under non-stress conditions. Legumes and root crops showed a greater increase and cereals less. Nitrogen deficiency reduced the average increase to 10%, as did warming by ca. 2°C. Two conclusions of the 2005 analysis were that C4 crops would not be more productive in elevated [CO2 ], except under drought, and that yield responses of C3 crops were diminished by nitrogen deficiency and wet conditions. Both stand the test of time. Further studies of maize and sorghum showed no yield increase, except in drought, while soybean productivity was negatively affected by early growing season wet conditions. Subsequent study showed reduced levels of nutrients, notably Zn and Fe in most crops, and lower nitrogen and protein in the seeds of non-leguminous crops. Testing across crop germplasm revealed sufficient variation to maintain nutrient content under rising [CO2 ]. A strong correlation of yield response under elevated [CO2 ] to genetic yield potential in both rice and soybean was observed. Rice cultivars with the highest yield potential showed a 35% yield increase in elevated [CO2 ] compared to an average of 14%. Future FACE experiments have the potential to develop cultivars and management strategies for co-promoting sustainability and productivity under future elevated [CO2 ].

Endophytic microbes: biodiversity, plant growth-promoting mechanisms and potential applications for agricultural sustainability.

Endophytic microbes are known to live asymptomatically inside their host throughout different stages of their life cycle and play crucial roles inthe growth, development, fitness, and diversification of plants. The plant-endophyte association ranges from mutualism to pathogenicity. These microbes help the host to combata diverse array of biotic and abiotic stressful conditions. Endophytic microbes play a major role in the growth promotion of their host by solubilizing of macronutrients such as phosphorous, potassium, and zinc; fixing of atmospheric nitrogen, synthesizing of phytohormones, siderophores, hydrogen cyanide, ammonia, and act as a biocontrol agent against wide array of phytopathogens. Endophytic microbes are beneficial to plants by directly promoting their growth or indirectly by inhibiting the growth of phytopathogens. Over a long period of co-evolution, endophytic microbes have attained the mechanism of synthesis of various hydrolytic enzymes such as pectinase, xylanases, cellulase, and proteinase which help in the penetration of endophytic microbes into tissues of plants. The effective usage of endophytic microbes in the form of bioinoculants reduce the usage of chemical fertilizers. Endophytic microbes belong to different phyla such as Actinobacteria, Acidobacteria, Bacteroidetes, Deinococcus-thermus, Firmicutes, Proteobacteria, and Verrucomicrobia. The most predominant and studied endophytic bacteria belonged to Proteobacteria followed by Firmicutes and then by Actinobacteria. The most dominant among reported genera in most of the leguminous and non-leguminous plants are Bacillus, Pseudomonas, Fusarium, Burkholderia, Rhizobium, and Klebsiella. In future, endophytic microbes have a wide range of potential for maintaining health of plant as well as environmental conditions for agricultural sustainability. The present review is focused on endophytic microbes, their diversity in leguminous as well as non-leguminous crops, biotechnological applications, and ability to promote the growth of plant for agro-environmental sustainability.

Mortierella elongata Increases Plant Biomass among Non-Leguminous Crop Species

Recent studies have shown that M. elongata (M. elongata) isolated from Populus field sites has a dual endophyte–saprotroph lifestyle and is able to promote the growth of Populus. However, little is known about the host fidelity of M. elongata and whether M. elongata strains differ from one another in their ability to promote plant growth. Here, we compared the impacts of three Populus-associated M. elongata isolates (PMI 77, PMI 93, and PMI 624) on the growth of seven different crop species by measuring plant height, plant dry biomass, and leaf area. M. elongata isolates PMI 624 and PMI 93 increased the plant height, leaf area, and plant dry weight of Citrullus lanatus, Zea mays, Solanum lycopersicum, and Cucurbita to a much greater degree than PMI 77 (33.9% to 14.1%). No significant impacts were observed for any isolate on the growth of Abelmoschus esculentus or Glycine max. On the contrary, Glycine max significantly decreased in height by 30.6% after the inoculation of M. elongata PMI 77. In conclusion, this study demonstrates that M. elongata generally promoted metrics of the plant performance among a diverse set of importantly non-leguminous crop species. Future research on understanding the molecular mechanisms that underlie strain and host variability is warranted.

Seasonal Abundance of Spotted Pod Borer, Maruca vitrata Fabricius in Early Pigeonpea [Cajanus cajan (L.) Millsp.] and its Management through Farmscaping in Uttar Pradesh

Field experiments were carried out in pigeonpea during Kharif 2014 to Kharif 2017 for Maruca vitrata Fabricius management through farmscaping approach with 7 different border crops (5 leguminous crops; 2 non-leguminous crops) and a sole crop. The M. vitrata larval webbing per plant was lowest and per cent decrease in webbing/plant over sole crop was highest in sorghum (2.05 and 60.95) as border crop followed by pearl millet (3.29 and 37.39). The highest mean number of Coccinella septumpunctata per plant (0.77), Cheilomenes sexmaculata per plant (0.85/plant) and spiders (0.76/plant) was recorded from sorghum as border crop with pigeonpea. The highest percent increase in above said natural enemies over sole crop was also recorded from sorghum as border crop treatment (755.6, 844.4 and 660). The highest pigeonpea yield (730.72 kg/ha) and per cent yield gain (65.81%) was also recorded with sorghum treatment. Among 5 weather parameters tested, day length (1.53) and relative humidity (-0.12) were found to influence the M. vitrata population significantly and its incidence was recorded from 41st SMW to 47th SMW.

Response of N2O emission to manure application in field trials of agricultural soils across the globe

The response of soil nitrous oxide (N2O) emission to manure application has been widely reported for laboratory experiments. However, the in-situ effects of manure application on soil N2O emission from field trials (i.e. real-world conditions) and related mechanisms are poorly understood at the global scale. Here, we performed a meta-analysis using 262 field observations from 44 publications to assess the in-situ effects of manure application on soil N2O emission and factors regulating N2O emission (e.g., agricultural practices, manure characteristics and initial soil properties). Our analysis found that manure application significantly increased soil N2O emission in field trials. The largest N2O emissions were observed in soils from warm temperate climates, planted with upland non-leguminous crops and using raw manure. Notably, water-filled pore space (WFPS) significantly affected N2O emission; soils with 50–90% WFPS had the highest N2O emissions. Initial soil properties (e.g. pH, texture and organic carbon (C)) were generally not significant for predicting N2O emission, possibly due to changes in soil properties induced by manure additions. Manures with carbon: nitrogen ratios (C:N) of 10–15 and C contents of 100–300 g C kg−1 produced the lowest N2O emission. The net N2O emission factor (1.13%) resulting from manure application was similar to additions of synthetic N fertilizer (1.25%) and crop residues (1.06%), suggesting that manure application resulted in a similar N2O emission to other soil amendments. Our analysis provides a scientific basis for manure management options to minimize N2O emissions from animal waste disposal on agricultural lands globally.

Effects of Non-Leguminous Cover Crops on Yield and Quality of Baby Corn (Zea mays L.) Grown under Subtropical Conditions

Effects of non-leguminous cover crops and their times of chopping on the yield and quality of no-till baby corn (Zea mays L.) were evaluated during two kharif seasons (May-August in 2014 and 2015) under subtropical climatic conditions of Punjab, India. The experiment was laid out in a split-plot design with four replications at Punjab Agricultural University’s Research Farm. Three cover crops (pearl millet (Pennisetum glaucum L.), fodder maize (Zea mays L.), and sorghum (Sorghum bicolor L.)) and the control (no cover crop) were in the main plots and chopping time treatments (25, 35, 45 days after planting (DAP)) in the subplots. During both kharif seasons, the yield (cob and fodder yield) and dry matter accumulation of baby corn following cover crop treatments, especially pearl millet, were significantly (p ≤ 0.05) higher than the control, and improved with increments in chopping time from 25 to 45 DAP. The effect of cover crops on baby corn quality (i.e., protein, starch, total soluble solids, crude fiber, total solid, and sugar content) did not differ among treatments, while increasing increments in chopping time had a significant effect on the protein and sugar content of baby corn. The use of cover crops and increment in chopping time helped in enhancing topsoil quality, especially available nitrogen; yet, the effect of cover crops and their times of chopping on topsoil organic carbon, phosphorus, and potassium did not differ among treatments. During both seasons, there was no significant interaction between cover crop and time of chopping among treatments with respect to baby corn yield and quality, as well as topsoil quality parameters.

Isolation and screening of rhizobacteria for various plant growth promoting attributes

Plant growth promoting rhizobacteria (PGPR) are beneficial bacteria that colonize plant roots and enhance plant growth through a variety of mechanisms that include improvement of plant nutrition, production and regulation of phytohormones, and suppression of disease causing organisms. A total of ten morphologically different bacterial strains were isolated from rhizospheric soil of leguminous and non-leguminous crops and were evaluated for their various PGPR activities. Most of the strains were Pseudomonas and Bacillus species followed by Rhizobium, Mesorhizobium and Azotobacter species. The PGP traits studied were ammonia production, indole acetic acid (IAA) production, HCN production, potassium solubilization, phosphate solubilization, siderophore production and zinc solubilization. Interestingly, strain PGP2, PGP5, PGP7, PGP8, PGP9 and PGP10 seems to be very promising and can be potentially used to promote plant growth and sustainable agriculture.