Influence of Land Configurations and Mulching on Plant Growth and Yield of Chickpea (Cicer arietinum L.)

Inadequate moisture supply and poor soil management are some of the major constraints for productivity in grain legumes like chickpea, present study was to focus on effect of land configurations and mulching in overcoming the constraints and their effect on growth and yield of chickpea. During rabi, 2019-20, the experiment was laid out in split plot design at College Farm, Agricultural College, Polasa, Jagtial with three land configurations (M1- Flat bed, M2- Ridge and furrow, M3- Broad bed and furrow) as main plots and four mulching treatments (S1- Control, S2- Sesamum mulch, S3- Gliricidia mulch, S4- Paddy straw mulch) as sub plots and are evaluated for growth and yield. Significant performance of the growth parameters was observed under broad bed and furrow land configuration and in contrast, flat bed land configuration recorded the least performance. Among the mulching treatments gliricidia recorded the better performance over other treatments.

K+ Nutrition Exchange in the Serendipita-Arabidopsis Symbiosis: Study of the Fungal K+ Transporters Involved

There is mounting evidence that the root-colonizing endosymbiotic fungus Serendipita indica improves plant growth. The beneficial effects have been observed when plants are growing in optimal conditions or under nutritionally deficient soils (e.g., phosphate poor soil) or exposed to stressful environmental conditions such as drought or salinity. However, until now its role in the nutrition of other plant essential macronutrient, such as K+, has not been fully clarified. Here, we study the role of the fungus in the K+ nutrition of Arabidopsis thaliana plants, during growth under K+ limiting conditions. As a first step, we studied the high-affinity K+ uptake of the plant and fungus when growing separately and in symbiosis. In the search for putative fungal actors involved in K+ nutrition, we also have cloned and functionally characterized the K+ transporters of S. indica SiHAK1, SiTRK1, SiTRK2, and SiTOK1, among which it has been shown that SiHAK1 is the main transporter involved in the K+ uptake in the high affinity range of concentrations. In addition, a gene expression study of these transporters and other candidates that could participate in the K+ homeostasis of the fungus has been carried out. The results indicated that, contrary to what happens with P nutrition, S. indica seems not to improve neither the growth nor the plant K+ reserves during K+ starvation. Instead, this nutritionally restrictive condition favored fungal colonization, suggesting that the fungus obtains the greatest benefit in K+ supply during symbiosis.

Deciphering the microbial and molecular responses of geographically diverse Setaria accessions grown in a nutrient-poor soil

The microbial and molecular characterization of the ectorhizosphere is an important step towards developing a more complete understanding of how the cultivation of biofuel crops can be undertaken in nutrient poor environments. The ectorhizosphere of Setaria is of particular interest because the plant component of this plant-microbe system is an important agricultural grain crop and a model for biofuel grasses. Importantly, Setaria lends itself to high throughput molecular studies. As such, we have identified important intra- and interspecific microbial and molecular differences in the ectorhizospheres of three geographically distant Setaria italica accessions and their wild ancestor S. viridis. All were grown in a nutrient-poor soil with and without nutrient addition. To assess the contrasting impact of nutrient deficiency observed for two S. italica accessions, we quantitatively evaluated differences in soil organic matter, microbial community, and metabolite profiles. Together, these measurements suggest that rhizosphere priming differs with Setaria accession, which comes from alterations in microbial community abundances, specifically Actinobacteria and Proteobacteria populations. When globally comparing the metabolomic response of Setaria to nutrient addition, plants produced distinctly different metabolic profiles in the leaves and roots. With nutrient addition, increases of nitrogen containing metabolites were significantly higher in plant leaves and roots along with significant increases in tyrosine derived alkaloids, serotonin, and synephrine. Glycerol was also found to be significantly increased in the leaves as well as the ectorhizosphere. These differences provide insight into how C4 grasses adapt to changing nutrient availability in soils or with contrasting fertilization schemas. Gained knowledge could then be utilized in plant enhancement and bioengineering efforts to produce plants with superior traits when grown in nutrient poor soils.

Sweet sorghum for phytoremediation and bioethanol production

As an energy crop, sweet sorghum (Sorghum bicolor (L.) Moench) receives increasing attention for phytoremediation and biofuels production due to its good stress tolerance and high biomass with low input requirements. Sweet sorghum possesses wide adaptability, which also has high tolerances to poor soil conditions and drought. Its rapid growth with the large storage of fermentable saccharides in the stalks offers considerable scope for bioethanol production. Additionally, sweet sorghum has heavy metal tolerance and the ability to remove cadmium (Cd) in particular. Therefore, sweet sorghum has great potential to build a sustainable phytoremediation system for Cd-polluted soil remediation and simultaneous ethanol production. To implement this strategy, further efforts are in demand for sweet sorghum in terms of screening superior varieties, improving phytoremediation capacity, and efficient bioethanol production. In this review, current research advances of sweet sorghum including agronomic requirements, phytoremediation of Cd pollution, bioethanol production, and breeding are discussed. Furthermore, crucial problems for future utilization of sweet sorghum stalks after phytoremediation are combed. Graphical Abstract

Changing Ground: Handling Tensions between Production Ethics and Environmental Ethics of Agricultural Soils

Soils are an essential element in sustainable food systems and vital for ecosystem services. Soils are degrading, because of urbanization, poor soil management, depletion and mining, over-use of inputs and impacts of climate change. Poor soil management resulted from short-term yield maximization caused by changes in land tenure, property rights and land use. We argue for soil protection based on the concept of soil telos defined as the combined purposefulness in agricultural production and terrestrial ecosystem optimization. It includes the right of mankind to use soils, provided norms and values are respected based on the soil’s usefulness, its natural purposefulness and its right to be protected (including its physical, chemical and biological cycles). Finding a sustainable balance between these values and rights on the one hand and the need to use living soils for agricultural production on the other hand requires a new approach to soil management based on widely accepted norm- and value-driven decisions on unavoidable trade-offs. Reconciling man-made telos and natural telos, requires (i) empowering the soil to achieve its man-made telos (e.g., by restoring degraded soils); (ii) empowering the soil to achieve its natural telos (e.g., by restoring water courses); (iii) raising awareness about the need to reconcile these two teloi (e.g., by acknowledging rights of soils); and (iv) monitoring tools to assess successful reconciliation (e.g., by evaluating soil health).

Harnessing Beneficial Plant-Microbe Interactions for Enhanced Plant Adaptation to Abiotic Stresses

Boosting crop production is a vital venture for enhancement of humanity. However, it remains a dream, especially in developing countries. To attain food security at household level, productivity is constrained by a several biotic and abiotic stresses. Yield losses are usually influenced by abiotic stresses, particularly drought and heat stress, and poor soil fertility. Optimal crop production under these stress factors requires substantial inputs, including irrigation and heavy fertilization, strategies which majority of farmers in poor countries lack capacity to exploit. Therefore, much more sustainable and accessible alternatives need to be developed in order to address the problem of food insecurity. Recently, research has proven that plant adaptation to abiotic stresses can be promoted by beneficial microbial species, especially those that reside in the rhizosphere. For instance, mycorrhizal fungi have been found to expand the root system of plants to access more water and nutrients. In-depth understanding of the mechanisms underlying beneficial plant-microbe interactions is key in development of holistic programs for boosting yields under abiotic stress conditions. This chapter seeks to unravel the mechanisms underlying beneficial plant-microbe interactions and the importance of these interactions in stress-adaptation.

Evaluation of the causes of flexible pavement failure; case study of Enugu/Port-Harcourt expressway

This study examined the causes of flexible pavement failure, taking the Enugu/Port-Harcourt expressway as a case study; to understand possible peculiarities. Chainages 101+400 and 125+925 were the most critical, having potholes of 500mm in depth; hence, soil samples were taken from these spots. The following tests were conducted: Particle size distribution, Atterberg limits, Permeability, Compaction, and California Bearing Ratio (CBR). The results obtained showed evidence of presence of clay in the subgrade; hence, concluding that the failure was mainly caused by poor soil material. From visual condition survey, it was noted that there were no drainages even at the critical paths of the alignment, and there was a significant proportion of Heavy Goods Vehicles (HGVs) which may not have been adequately considered during design.

Role of Rhizosphere Soil Microbes in Adapting Ramie (Boehmeria nivea L.) Plants to Poor Soil Conditions through N-Fixing and P-Solubilization

The N-fixing and P-solubilization functions of soil microbes play a vital role in plant adaptation to nutrient-deficiency conditions. However, their exact roles toward the adaptation of ramie to poor soil conditions are still not clear. To fill this research gap, the N-fixing and P-solubilization efficiencies of soils derived from the rhizosphere of several ramie genotypes with different levels of poor soil tolerance were compared. Correlations between the N-fixing, P-solubilization efficiency, and the poor soil tolerable index were analyzed to quantify their contributions towards the adaptation of ramie plants to poor soil conditions. To explore how the microorganisms affected the potential of N-fixing/P-solubilization, the activities of the nutrients related the soil enzymes were also tested and compared. The results of this study confirm the existence of N-fixing and P-solubilization bacteria in the ramie rhizosphere of the soil. The number of N-fixing bacteria varied from 3010.00 to 46,150.00 c.f.u. per gram dry soil for the ramie treatment, while it was only 110.00 c.f.u. per gram dry soil for treatment without ramie cultivation. The average P-solubilization efficiency of ramie treatment was almost five times higher than that of the control soil (0.65 vs. 0.13 mg mL−1). The significant correlations between the poor soil tolerance index and the N-fixing bacteria number (r = 0.829)/nitrogenase activity (r = 0.899) suggest the significantly positive role of N-fixing function in the adaptation of ramie plants to poor soil. This is also true for P-solubilization, as indicated by the significant positively correlation coefficients between the ramie poor soil tolerance index and P-solubilization efficiency (0.919)/acid phosphatase activity (0.846). These characteristics would accelerate the application of “holobiont” breeding for improving ramie nutrient use efficiency.

Release and distribution changes of phosphorus in three alkaline sandy soils as a function of bone char applications

An incubation experiment was carried out to assess bone char application on the availability and distribution of phosphorus in agricultural alkaline sandy soils. Three alkaline agricultural sandy soils in Upper Egypt have been collected from Arab El-Awamer at Assiut governorate, West El-Minia at El-Minia governorate, and New Valley Governorate. 100 grams were taken from each soil under study and placed in a plastic jar. The bone char is applied at level 0.4 g jar-1 into these soils. This experiment was incubated at 23 ºC in the dark for periods of 7, 16, 35, 65, and 84 days and arranged in a completely randomized design with three replicates. The results revealed that bone char applications to the soils resulted in a significant positive increase in the availability of phosphorus affected by the soil type and incubation periods in Arab El-Awamer soil. The percentage of increase in available phosphorous after adding bone char compared to before incubation was as follows: Arab El-Awamer soil ˃New Valley soil ˃West El-Minia soil. The available phosphorous was negatively correlated with electrical conductivity (r=-0.288*), soluble calcium (r=-0.306*), and soluble sulfate (r=-0.413*). The concentrations of NH4Cl-Pi, NaHCO3-Pi, NaOH-Pi, HCl-Pi, residual-P fractions increased significantly in some soil types with applying bone char. The concentrations of available phosphorous in all soils under study were positively correlated with all phosphorus fractions. We conclude that bone char applications into P-poor soil are important to potentially enhance phosphorus availability. Bone char is considered a promising strategy in sustainable agriculture.