Genotypic Variation in Cultivated and Wild Sorghum Genotypes in Response to Striga hermonthica Infestation

Striga hermonthica is the most important parasitic weed in sub-Saharan Africa and remains one of the most devastating biotic factors affecting sorghum production in the western regions of Kenya. Farmers have traditionally managed Striga using cultural methods, but the most effective and practical solution to poor smallholder farmers is to develop Striga-resistant varieties. This study was undertaken with the aim of identifying new sources of resistance to Striga in comparison with the conventional sources as standard checks. We evaluated 64 sorghum genotypes consisting of wild relatives, landraces, improved varieties, and fourth filial generation (F4) progenies in both a field trial and a pot trial. Data were collected for days to 50% flowering (DTF), dry panicle weight (DPW, g), plant height (PH, cm), yield (YLD, t ha−1), 100-grain weight (HGW, g), overall disease score (ODS), overall pest score (OPS), area under Striga number progress curve (ASNPC), maximum above-ground Striga (NSmax), and number of Striga-forming capsules (NSFC) at relevant stages. Genetic diversity and hybridity confirmation was determined using Diversity Arrays Technology sequencing (DArT-seq). Residual heterosis for HGW and NSmax was calculated as the percent increase or decrease in performance of F4 crossover midparent (MP). The top 10 best yielding genotypes were predominantly F4 crosses in both experiments, all of which yielded better than resistant checks, except FRAMIDA in the field trial and HAKIKA in the pot trial. Five F4 progenies (ICSVIII IN × E36-1, LANDIWHITE × B35, B35 × E36-1, F6YQ212 × B35, and ICSVIII IN × LODOKA) recorded some of the highest HGW in both trials revealing their stability in good performance. Three genotypes (F6YQ212, GBK045827, and F6YQ212xB35) and one check (SRN39) were among the most resistant to Striga in both trials. SNPs generated from DArT-seq grouped the genotypes into three major clusters, with all resistant checks grouping in the same cluster except N13. We identified more resistant and high-yielding genotypes than the conventional checks, especially among the F4 crosses, which should be promoted for adoption by farmers. Future studies will need to look for more diverse sources of Striga resistance and pyramid different mechanisms of resistance into farmer-preferred varieties to enhance the durability of Striga resistance in the fields of farmers.

Influence of Conventional and Non-conventional Organic Sources of Plant Nutrients and Industrial Refuse for Yield and Quality Enhancement of Radish

Background: India generates about 50 million tons of municipal solid wastes (MSW) every year. Composting MSW is viewed as a low-cost method of diverting organic wastes from landfills in to a valuable product of agricultural importance. Farm Yard Manure (FYM) is an organic matter rich with a small quantity of nitrogen, while rice hull ash is a good source of plant nutrients particularly of potash. Bagasse ash is a waste obtained from sugar industries and is capable of supplying significant amount of plant nutrients. The present investigation aimed to study the effect of organic sources of plant nutrients and industrial waste on yield and quality of radish as a supplementary source of plant nutrients.Methods: A pot trial investigation was carried out during 2019 at Annamalai University, Chidambaram, Tami Nadu to study the influence of conventional and non-conventional organic sources of plant nutrients and industrial refuse on yield and quality of radish. Under this trial, FYM (12.5 t ha-1), Municipal Solid Waste Compost (25 t ha-1), Rice hull ash (5 t ha-1), Bagasse ash (10 t ha-1) with 100% RDF and 75% RDF were tried.Result: The present investigation under pot trial showed that the maximum radish root yield, shoot yield and quality were observed due to the application of organic sources of plant nutrients of both conventional and non-conventional organic sources and industrial refuse.

Increasing rock phosphate efficient use through soil amendment with waste biomasses

<p>Loss of soil organic carbon content can limit the soil's ability to provide goods and services. In agricultural soil this may lead to lower yields and affect food security. In this context, the proper use of waste biomasses as soil amendment is a valuable alternative to disposal with numerous benefits to soil fertility with a direct effect on soil organic matter content. Moreover, beside this direct effect waste biomasses can have a beneficial result on nutrients.</p><p>In modern agriculture the use of rock phosphate as fertilizer is crucial but abused. Although this non-renewable resource reserves may be depleted in 50-100 years, many farmers still use overabundant amount of rock phosphate-based fertilizers with an additional environmental burden. From a chemical point of view the efficient use of rock phosphate can be increased by some agricultural practices and amending soil with waste biomasses is one of them.</p><p>Here we propose the use of 3 different waste biomasses on phosphate rock dissolution and subsequent phosphorus availability. The 3 waste biomasses, citrus pomace, olive oil mill waste and barley spent grains, were selected mainly for their potential direct or indirect effect on pH. This experiment was composed by two steps a bench and a pot trial. In the bench trial the waste biomasses and phosphate rock were mixed and transferred in litterbags. In these litterbags pH, water soluble P, matter loss and total P were destructively analyzed each 10 days for a month. In the pot trial the same combination of waste biomasses and phosphate rock were tested in a soil plant system; some agronomic parameters were measured on rocket salad and pH, soil-P availability, acid phosphatase activity were analyzed in soil.</p><p>In bench trial, barley spent grain plus phosphate rock shows the highest water soluble P, citrus pomace plus phosphate rock showed a significant correlation between water soluble P and pH while olive oil mill waste plus phosphate rock has high correlation between water soluble P and matter loss. These two treatments were also the best performing in the pot trial in terms of rocket salad yield and soil available P. Even though the investigation was conducted on a short lived experiment, some results are encouraging and displays good agronomic performances of waste biomasses plus phosphate rock. Nevertheless, next studies should consider other waste biomasses within longer experiments. Additionally, scaling up the experiment to a field application can provide more thorough information about the effects on soil organic carbon and P dynamics.</p>

Field Performance of Allelopathic Bacteria for Biological Weed Control in Wheat: Innovative, Sustainable and Eco-Friendly Approach for Enhanced Crop Production

Application of allelopathic bacteria (AB) for weed suppression may be helpful to solve various environmental challenges posed by conventional weed control techniques. In our earlier studies, around 400 strains of rhizobacteria of five weeds and wheat were isolated, screened for production of phytotoxic substances, and tested for phytotoxic activity on wild oat and little seed canary grass, and possible effects on wheat under laboratory conditions. We obtained 13 strains inhibitory to wild oat (Avena fatua L.) and 11 to little seed canary grass (Phalaris minor Retz.). Five of these (13 and 11) strains also suppressed wheat (Triticum aestivum L.) while others either stimulated or remained ineffective on wheat in separate bioassays. The success of any weed biocontrol technique, however, depends on its response under field conditions. Therefore, the present study was conducted to investigate biological weed control of the five most efficient strains of AB under natural conditions in pot and field trials. Wheat was artificially invaded with wild oat in the pot trial through seeding. Wheat of the field trial was artificially invaded with wild oat and little seed canary through seeding. The selected strains belonged to pseudomonads (Pseudomonas putida, P. fluorescence, P. aeruginosa, and P. alcaligenes) and their inocula were prepared using sterilized peat. The inoculated seeds of wild oat and wheat were sown together in a pot trial. The inoculated seeds of wild oat, little seed canary grass, and wheat were sown together in the field experiment. The field was selected based on chronic infestation of these weeds. However, weed invasion was ensured by adding seeds of weeds (inoculated with the respective strains of AB, according to treatment plan). A severe invasion of wild oat was observed in the pot trial, which reduced the grain yield of infested wheat up to 60.8%. The effectiveness of applied strains controlled 22.0–76.3% loss of grain yield of infested wheat. Weed invasion in the field trial reduced the grain yield of the crop up to 56.3% and effectiveness of the applied strains controlled 29.0–60.7% loss of grain yield of infested wheat. The study of other agronomic, physiological, and chemical parameters of the crop and weeds supported these findings. Harnessing the potential of these strains exhibited in our studies may be helpful to introduce an innovative, sustainable, and eco-friendly weed control technique for production of wheat.

Assessment of Recycling-derived Fertilizers as an Alternative to Mineral Fertilizers – Effects on the Soil Microbiome

Phosphorus (P) is an essential macronutrient for all living organisms and is applied as fertilizer in agroecosystems to improve crop growth. Recycling-derived fertilizers (RDFs) have been developed for nutrient recovery from Europe’s largest waste streams as a sustainable alternative to this finite resource. The impact of four RDFs (two ashes, two struvites) on the soil microbiome in comparison with a P-free control and triple super phosphate (TSP) as mineral fertilizer was investigated in a pot trial and a subsequent microcosm trial (subset of samples). For both experiments perennial ryegrass was cultivated for 54 days. The pot trial was conducted at P fertilization rates of 20 and 60 kg P ha-1 in quadruplicates. After the pot harvest the bulk soil was stored until the microcosm trial was conducted, using the control, TSP and the two ashes at 60 kg P ha-1 in six replicates. Pot trial results showed highest P bioavailability from struvites at high P rates, also resulting in higher biomass yield on average. Furthermore, P solubilization capabilities from tri-calcium phosphate was enhanced in the RDFs treatments, while the TSP treatments were negatively affected. For the microcosm trial, most probable number (MPN) analysis showed that phytate-utilizing bacterial abundance was significantly increased in one of the ashes and had also remained higher in the RDF treatments after storage. Understanding the effects of recycling-derived fertilizer application on the soil P cycle is vital for developing a more sustainable agriculture.

Toxic Effects of Single Antibiotics and Antibiotics in Combination on Germination and Growth of Sinapis alba L.

Antibiotics enter agro-ecosystems via the application of farmyard manure, sewage sludge, animal by-products, or digestates. There are many open questions regarding the behavior of such compounds in the soil like their adsorption, degradation, half-life, and their effects on soil organisms and plants. The impact of antibiotics on the development of antibiotic resistance genes in the environment is regarded as the most important effect that endangers the environment as well as human health. Nevertheless, direct plant toxicity, especially of different antibiotics and heavy metals at the same time, can be of importance as well. In the current study, commercially available phytotoxkits were tested with regard to the toxicity of single antibiotics and antibiotics in combination with the root growth of Sinapis alba L. Additionally, a pot trial was conducted to study the transfer of the observed phytotoxkits results in more complex systems. The phytotoxkits revealed direct toxicity of antibiotics on root development only at high concentrations. The highest toxicity was determined for sulfadiazine, followed by tetracycline and enrofloxacin, showing the least toxicity. When two antibiotics were tested at the same time in the phytotoxkit, synergistic effects were detected. The pot trial indicated lower effect concentrations for enrofloxacin than determined in the phytotoxkit and, therefore, to higher toxicity on plant growth.

Improving the efficacy of selenium fertilizers for wheat biofortification

Increasing the selenium (Se) concentration of staple crops by fertilization is a valuable pathway to increase Se in the human diet, thus preventing Se deficiency. A pot trial was set up to investigate whether the application of 3.33 µg kg−1 of Se (equivalent to 10 g ha−1) to wheat can be made more efficient by its co-application with macronutrient carriers, either to the soil or to the leaves. In the soil, Se was applied either on its own (selenate only) or as a granular, Se-enriched macronutrient fertilizer supplying nitrogen, phosphorus, potassium or sulfur. Selenium was also applied to leaves at head emergence with, or without, 2% w/v N fertilizers. With grain Se concentrations varying from 0.13–0.84 mg kg−1, soil application of selenate-only was 2–15 times more effective than granular Se-enriched macronutrient fertilizers in raising grain Se concentrations. Co-application of foliar Se with an N carrier doubled the Se concentration in wheat grains compared to the application of foliar Se on its own, the majority of which was in the highly bioavailable selenomethionine fraction. Results from this study demonstrate the possibility of improving the efficacy of Se fertilizers, which could enrich crops with Se without additional application costs in the field.