Soil Quality Assessment under Restorative Soil Management Practices in Soybean (Glycine Max) after Six Years in Semi-Arid Tropical Black Lands of Central India

Vertisol soils of central India are heavy in texture, with high clay content and low organic matter. These soils are prone to degradation and the soil loss is due to poor management practices including excessive tillage. Based on a long-term study conducted for improving the quality of these soils, it was found that management practice such as low tillage (LT) + 4 t ha^?1 compost + herbicide (Hb) recorded significantly higher organic carbon (OC) (6.22 g kg^?1) and available N (188.5 kg ha^?1) compared to conventional tillage (CT) + recommended fertilizer (RF) + off-season tillage (OT) + hand weeding (HW) (OC: 4.71 g kg^?1, available nitrogen (N) (159.3 kg ha^?1). Among the physical soil quality parameters, mean weight diameter (MWD) was significantly higher under LT + 4 t ha^?1 straw + Hb (0.59 mm). The practice of LT + 4 t ha^?1 straw + HW recorded significantly higher microbial biomass carbon (MBC) (388.8 μg g^?1). The order of key indicators and their contribution towards soil quality was as follows: OC (29%) >, MBC (27%) > available zinc (Zn) (22%) > MWD (9%) > available boron (B) (8%), > dehydrogenase activity (DHA) (5%). The order of the best treatment which maintained soil quality index (SQI) values reasonably good (>1.5) was as follows: LT + 4t ha^?1 compost + HW (1.65) > LT + 4 t ha^?1 compost +Hb (1.60) > LT + 4t ha^?1 straw + HW (1.50). Hence, these treatments could be recommended to the farmers for maintaining higher soil quality in Vertisols under soybean system. Correlation studies revealed stronger relationship between key indicators like OC (R² = 0.627), MBC (R² = 0.884), available Zn (R² = 0.739) and DHA (R² = 0.604) with Relative Soil Quality Index (RSQI). The results of the present study would be highly useful to the researchers, farmers and land managers.     

Cell wall polysaccharides from chalkumra (Benincasa hispida) fruit. Part I. Isolation and characterization of pectins

Pectic polysaccharides were obtained from chalkumra (Benincasa hispida) fruit by sequential extraction with ammonium oxalate (fraction BOX), dilute acid (fraction BHCl), and cold dilute alkali (fraction BOH). The highest yield of polysaccharides was obtained with oxalate and HCl. BOX was enriched in partly methyl-esterified galacturonic acid, whereas BHCl and BOH contained mostly galactose. All of the extracts showed similar elution patterns in size exclusion chromatography although the intrinsic viscosities (eta) were different (132 +/- 6, 100 +/- 5, and 285 + 10 mL/g for BOX, BHCl, and BOH, respectively). From fractionation by anion exchange chromatography, homogalacturonan (as seen from sugar analysis and Fourier transform infrared spectrum) accounted for more than half of BOX and 11% of BHCl. Methylation analyses and hydrolysis of BHCl with endo-beta-(1-->4)-d-galactanase showed the presence of beta-(1-->4)-d-galactan. The neutral galactan represented more than 76% of BHCl and approximately 40% of BOH. The other polysaccharides were complex galactans in BOH and an acidic arabinan (<1%) in BOX and BHCl.     

New techniques for breeding maize (Zea mays) varieties with fall armyworm resistance and market-preferred traits for sub-Saharan Africa

Deploying maize varieties with fall armyworm (Spodoptera frugiperda [J.E. Smith]; FAW) resistance, desirable product profiles (PPs) and climate resilience is fundamental for food and economic security in sub-Saharan Africa (SSA). This study reviewed and identified challenges and opportunities for effective and accelerated breeding of demand-led maize hybrids with FAW resistance and adaptation to the diverse agro-ecologies of SSA. Lessons were drawn on improving breeding efficiency through adequate genetic variation delivered via prebreeding programmes, speed breeding and a reduced breeding stage plan. Appropriate PPs aligned with demand-led breeding approaches were highlighted as foundations for variety design and commercialization. Challenges to accelerated FAW resistance breeding in maize included inadequate funds and modern tools; poor adaptation of some exotic donor parental lines; lack of information on FAW resistance among local varieties; lack of integration of molecular markers associated with FAW resistance and agronomic traits into selection plans; and limited infrastructure for FAW rearing and germplasm screening. Integration of modern breeding tools and scientific innovations were recommended for accelerated development and release of FAW resistant and market-preferred maize varieties.     

Inheritance of plant elongation ability at seedling stage in rice

Summary In a comparison of methods to study inheritance of plant elongation ability, 15-, 20-, 25-, 30-, and 35-day-old F₂ populations of a cross between Baisbish (floating variety) and IR42 (nonelongating semidwarf modern variety) of rice, (Oryza sativa L.) were subjected to 65 cm water depth for 7 days. Frequency distribution of plant height before and after submergence was obtained. Bimodal curves in 15-, 20- and 25-day-old populations gave good fits to 9:7 elongating: nonelongating plants, suggesting that elongation was due to two dominant complementary genes. Segregation in the 30-day-old population was not clear-cut. A seedling age of 20 days was subsequently chosen for further studies.Two F₂'s involving floating rice and a nonelongating semidwarf; four F₂'s involving floating rice and an elongating semidwarf; and two F₂'s involving elongating and nonelongating semidwarf parents were studied with 20-day-old seedlings in the same way. Floating rice combinations with nonelongating semidwarf parents as well as with elongating semidwarf parents segregated into 9:7 elongating: nonelongating ratio. It is possible that because elongating and nonelongating dwarf parents did not differ much in elongation ability at seedling age, their combination with floating rice parents provided similar segregation. The F₂ distributions for height in elongating and nonelongating dwarf cross combinations were continuous with one peak.Genetic constitution of parents proposed are Sd1 Sd1 El El for floating parents, sd1 sd1 El El for semidwarf elongating, and sd1 sd1 el el for dwarf nonelongating.     

Lysimeter study on the use of biodrainage to control waterlogging and secondary salinization in (canal) irrigated arid/semi-arid environment

The study describes the capacity of trees to control the rise in water table and thus prevent the formation of waterlogged soils and development of secondary salinization in canal irrigated areas. It was conducted in RCC lysimeters of 1.2 m dia. and 2.5 m depth filled with sandy loam alluvial soil (Typic Ustochrept), with provisions to maintain water table depth at 1, 1.5 and 2 m from the surface and groundwater salinity at 0.4, 3, 6, 9 and 12 dS m-1. The amount of water biodrained by eucalyptus (Eucalyptus tereticornis) and bamboo (Bambusa arundinacea) at the given water table depths and groundwater salinity levels was monitored over four years by daily measuring the water needed for maintaining the water table. The trees continued to absorb and transpire water throughout the year, the capacity being more in summer and rainy than that was in the winter season. The eucalyptus plant could biodrain 2880, 5499, 5518 and 5148 mm of water in the first, second, third and fourth year of study period, from non-saline groundwater and a water table depth of 1.5 m. The amount of water biodrained was more at 1.5 m as compared to 1 and 2 m water table depths. The biodrainage capacity of trees was significantly affected by the salinity of the groundwater. However, even at salinity of 12 dS m-1, the eucalyptus plant biodrained 53% of that under non-saline conditions. It was calculated that biodrainage could control water table rises upto 1.95, 3.48, 3.76 and 3.64 m in first, second, third and fourth year, respectively. The secondary salinity developed in the root zone, upto 45 cm depth, did not exceed 4 dS m-1 even at water table depth of 1 m with salinity of 12 dS m-1. The volume of water biodrained by bamboo increased with time and could control water table rises upto 1.09, 1.86, 2.46 and 2.96 m in first, second, third and fourth year of growth, respectively.This study indicates that due to high transpiration capacity and an ability to extract water from deeper layers containing saline groundwater, the trees can control the rise in water table in irrigation command areas and prevent the formation of waterlogged and eventually the saline wastelands.     

Isolation,partial identification and application of diazotrophic rhizobacteria from traditional Indian rice cultivars

A diversity of N₂-fixing (diazotrophic) bacteria was isolated from two traditional rice cultivars, Sataria and Kartiki, from the rice growing area of Mithila region of North Bihar, India, where low levels of nitrogen fertilizers are applied. Nitrogen-free semisolid media NFb, JMV and LGI with different carbon sources and pH-values were used for enrichment and isolation of root-associated diazotrophs. The colonization density of roots by diazotrophs, as estimated from positive pellicle formation at highest dilution in nitrogen-free enrichment media, was 10⁶–10⁸ diazotrophic bacteria per g fresh root weight. Roots of the cultivar Kartiki were found to be more densely colonized endophytically by diazotrophs as detected after chloramine T (1%) surface disinfection. To ascertain the phylogenetic affiliation of the isolates, phylogenetic oligonucleotide probes and the Fluorescent in situ Hybridization (FISH) technique were applied. Using group-specific rRNA directed oligonucleotide probes, the majority of the isolates could be identified as alpha-, beta-, or gamma-proteobacteria. Using 16S and 23S rRNA-directed genus- or species-specific probes, Herbaspirillum seropedicae, Azospirillum amazonense, Burkholderia cepacia/vietnamiensis, Rhizobia and Pseudomonas spp. were found to be the most prominent root associated culturable diazotrophs. Diazotrophic Gluconacetobacter spp. were also demonstrated as colonizers of rice roots. Burkholderia cenocepacia, Pseudomonas sp. and three diazotrophic PGPR reference strains were used for the inoculation of axenically grown rice seedlings to determine the plant growth promoting potential. Significant increases in the shoot length (up to 60%), shoot dry weight (up to 33%) and the grain yield (up to 26%) per plant were observed in non-axenic pot and field trials. Using semisolid enrichment media after surface sterilization of field grown inoculated rice roots and oligonucleotide probing of the diazotrophic enrichment cultures, a sustainable colonization with the inoculated bacteria could be demonstrated.     

Soil Organic Matter/Carbon Dynamics in Contrasting Tillage and Land Management Systems: A Case for Smallholder Farmers with Degraded and Marginal Soils

This study reveals that soil organic matter (SOM) is 58% soil organic carbon (SOC) and the processes that govern SOM dynamics include those that promote SOM synthesis from organic inputs and those that decrease SOM through decomposition. Land use is a key determinant of SOC dynamics and spatial differences in SOM. Agricultural soils can accommodate extra carbon (C) between 140 and 170 Pg C. Globally sub soils store more than half of total SOC. The SOM can increase under no-tillage management even with low crop residue input. Soil tillage induces loss of carbon in macroaggregates (>250 μm) and a gain of carbon in microaggregates (<250 μm). The stage of plant development rather than plant species determines carbon dynamics from plants to soil, and the rate depends on the plant development. However, sorption of dissolved organic matter to mineral soil influences the stabilization of dissolved organic matter.     

Molecular markers based genetic relatedness studies in tissue culture propagated japanese plum cultivars Santa Rosa and Frontier

Genetic Resources and Crop Evolution - Santa Rosa and Frontier are the major Japanese plum (Prunus salicina Lindl.) cultivars grown throughout the world. The present investigation was performed to...     

Some plants like it warmer: Increased growth of three selected invasive plant species in soils with a history of experimental warming

Soil warming can affect plant performance by increasing soil nutrient availability through accelerating microbial activity. Here, we test the effect of experimental soil warming on the growth of the three invasive plant species Trifolium pratense (legume), Phleum pratense (grass), and Plantago lanceolata (herb) in the temperate-boreal forest ecotone of Minnesota (USA). Plants were grown from seed mixtures in microcosms of soils with three different warming histories over four years: ambient, ambient +1.7 °C, and ambient +3.4 °C. Shoot biomass of P. pratense and P. lanceolata and plant community root biomass increased significantly in soils with +3.4 °C warming history, whereas T. pratense responded positively but not significantly. Soil microbial biomass and N concentration could not explain warming effects, although the latter correlated significantly with the shoot biomass of P. lanceolata. Our results indicate that soil with a warming history may benefit some invasive plants in the temperate-boreal ecotone with potential impacts on plant community composition. Future studies should investigate the impact of warming-induced differences in soil organisms and nutrients on plant invasion.     

Effect of 46 years' application of fertilizers,FYM and lime on physical,chemical and biological properties of soil under maize–wheat system in an acid Alfisol of northwest Himalayas

Imbalanced fertilizer use with intensive cropping has threatened the sustainability of agroecosystems, especially on acid soils. An understanding of the long-term effects of fertilizers and amendments on soil health is essential for sustaining high crop yields. The effects of application of fertilizers, and amendments for 46 years on soil properties and maize yield in an acid Alfisol were investigated in this study. Ten fertilizer treatments comprising different amounts of NPK fertilizers, farmyard manure (FYM) and lime, and one control, were replicated three times in a randomized block design. At 0–15 cm soil depth, bulk density was least (1.20 t/m³), porosity (49.8%) and water holding capacity (61.7%) were greatest in 100% NPK + FYM, corresponding to the largest organic carbon content (13.93 g/kg). Microbial biomass C and dehydrogenase activity in 100% NPK + FYM were 42% and 13.7% greater than 100% NPK, respectively. Available nutrients were significantly more with 100% NPK + FYM and 100% NPK + lime than control and other fertilizer treatments. At 15–30 cm depth, the effect of various treatments was comparable to the surface layer. Grain yield declined by 55% and 53% in 100% NPK(-S) and 100% NP, respectively, compared with 100% NPK, whereas 100% N as urea alone eventually led to crop failure. Soil porosity recorded the greatest positive correlation (r = .933**), whereas bulk density recorded a negative significant correlation (r = −.942**) with grain yield. The results suggest that integrated use of FYM/lime with chemical fertilizers is a sustainable practice in terms of crop yield and soil health, whereas continuous application of urea alone is detrimental to the soil health.