Total Dry Biomass Research Articles

Pemanfaatan Pupuk Hayati-fosfat untuk Meningkatkan Pertumbuhan Tanaman Jagung (Zea mays L.) di Entisol

Entisols are low fertility soils that require high doses of inorganic fertilizers to support plant growth. On the other hand, it was reported that biofertilizers can be applied to support plant growth. The purpose of this study was to examine the ability of bio-phosphate fertilizers to affect plant growth. The greenhouse experiment was arranged according to a completely randomized design, consisting of five treatments of different fertilization and each treatment was repeated four times. Experimental treatments were P1) control; P2) biological-phosphate fertilizer treatment; P3) treatment of NPK fertilizers; P4) integrated fertilizer treatment of 2 combinations of fertilizers (biological-phosphate & NPK); P5) integrated treatment of 3 combinations of fertilizers (biological-phosphate, NPK & organic). The dose of NPK fertilizer is 75% of the recommended dose. The experimental soil has a sandy loam texture, pH-soil 6.01, content of C-organic1.20%, N-total 0.09%, P-available 5.68 ppm and Kdd 0.31cmol/kg. The results showed that the application of a single biological phosphate fertilizer had no significant effect on plant growth compared to the control. A significant effect was obtained on integrated fertilization, both with two combinations of fertilizers (P4) and with three combinations of fertilizers (P5). The highest plant growth rate, with reference to the total dry biomass of plant shoots and roots, was obtained in treatment P5 with plant growth rates reaching 232.14% higher than the single treatment of biological fertilizers (P2), 53.70% higher than the single treatment of NPK fertilizers (P3) and 16.35% higher than the integrated treatment of two combinations of fertilizers (P4).

Biofertilizer based on echinochloa pyramidalis (lam.), panicum maximum l., tithonia diversifolia (hemsel.) a. gray and cow dung, an alternative to the use of chemical fertilizers in urban and peri-urban agriculture in Brazzaville, Republic of Congo

Rural agricultural production that feeds urban areas is supplemented by products from urban and peri-urban agriculture, which, to compensate for low yields, resort to practices that are not very environmentally friendly. The market belts of Brazzaville are no exception to these practices. Chemical fertilizers are used to raise production levels. The present study was undertaken to contribute to the mitigation of the excessive use of chemical fertilizers in these vegetable markets, through biofertilizers that could optimize crop yields. Two completely randomized blocks with six treatments each of E. pyramidalis, P. maximum, T. diversifolia and cow dung were set up. Each treatment had 30 plants in the first set-up and 81 plants in the second. The first set-up was first cultivated with Amaranthus hybridus L.. Mineral fertilizer NPK 15-15-15 and NPK 20-10-10 was used as control. Growth parameters of crown Height and Diameter were measured every seven days until harvest. The dry biomass was estimated with 35 plants per treatment and per replication for the second experimental design. Results obtained show case low overall mortality rates of about 1.1% for the first set-up and 2.05% for the second set-up. The variance analysis at the 5% threshold, during harvest, revealed a treatment impact on height (P<0.001), crown diameter (P<0.001) for both experimental designs, and total dry biomass (P<0.001). The combinations E. pyramidalis + T. diversifolia, E. pyramidalis + P. maximum + T. diversifolia + Cow dung and P. maximum + T. diversifolia were the best.

Halotolerant rhizobacteria enhance the tolerance of the desert halophyte Nitraria schoberi to salinity and dust pollution by improving its physiological and nutritional status

Playas have a high potential for producing dust, sand, and salt storms, which can influence human health and agricultural land in the near future. Growing vegetation is an effective way to control wind erosion, but events like soil salinity and dust storms prevent vegetation from settling in these areas. In this study, the effects of two halotolerant plant growth-promoting rhizobacterial strains, Bacillus pumilus HR and Zhihengliuella halotolerans SB, on morpho-physiological and nutritional status of the desert halophyte Nitraria schoberi under the stress of salinity (0, 300, and 600 mM NaCl) and dust (0 and 1.5 g m−2 month−1) were examined. The results showed that salinity, dust and the combination of the two stresses had a negative effect on most morphological and physiological traits of the plant. Salinity stress reduced potassium, iron, and manganese of N. schoberi by 28, 30, and 21 %, and increased anthocyanins, proline, and peroxidase by 21, 92, and 16 %, respectively. Both bacterial strains and their combination improved plant growth against such stresses. The effect of B. pumilus HR strain was more than that of Z. halotolerans SB strain on the plant. HR strain and SB strain increased chlorophyll a by 62 and 25 %, total dry biomass by 66 and 31 % at 300 mM NaCl level, respectively, and significantly increased seedling quality index by 72 and 76 %, respectively, under dust stress. The results of principal component analysis (PCA) showed that the presence of bacterial strains decreased antioxidant compounds (negative correlation) and increased mineral elements, chlorophyll, total dry biomass, and seedling quality index. This information can help us in the optimal afforestation of this plant species and the fixation of salt dust in the playa under the conditions of climate change in arid and semi-arid ecosystems.

Estimation of biomass and carbon sequestration capacity of the Surra mountain plantation forest in Gamo Highlands, Southern Ethiopia

AbstractThis study was aimed at estimating the carbon sequestration potential of the Surra planted forest on Gughe massive of the Gamo highlands in Southern Ethiopia based on tree species type. The plantation was established on degrading pasture land in the mid‐1980s during the golden era of plantation forest expansion history in Ethiopia. The Surra plantation forest was stratified upon three tree species namely E. globulus, C. lusitanica, and P. radiata. The data were collected from 32 sample plots (20 E. globulus, 10 C.lusitanica, and 2 P. radiata plots, each having 10 m*10 m in size), and were laid at random at the inner part of the plantation. The Species‐specific allometric equations and the pan‐tropical allometric model were used to estimate the aboveground biomass and carbon stock of the forest. The average “tree height,” “diameter at breast height,” and “tree stand density” per hectare were the highest for C. lusitanica and the lowest for E. globulus (except the wood density). The wood‐specific density/g/cm3 was the largest for E. globulus. The average carbon sequestered in C. lusitanica (53.9 ton/ha) was significantly larger than E. globulus (35.6 ton/ha) and P. radiata (43.8 ton/ha). The estimated average carbon stock/ha of eucalyptus was the lowest due to its low stand density caused by illegal encroachment for construction, energy, and cash income purposes. The total dry biomass and carbon sequestrated are determined by area proportion; hence, eucalyptus covered an extensive area accounting for slightly less than two‐thirds of the total Surra plantation forest followed by Cupressus. The mean carbon stock (40.3 ton/ha) of the Surra plantation is lower compared with many plantation forest stock values under better management. The findings revealed that the significant variation in carbon stock with other forests despite the similarities in age, climate, location, and aspect was the result of encroachment, illegal cutting, frequent grazing, and limited protection, and call for policy attention from the Ethiopian government.

Mycorrhizal species selectivity of sweet sorghum genotypes and their effect on nutrients uptake

ABSTRACT This study aimed to find the effects of several mycorrhiza species on agronomic characteristics and nutrient uptake of various sweet sorghum genotypes under the semi-arid Mediterranean soil conditions. Four sweet sorghum genotypes were inoculated with three mycorrhiza species under greenhouse conditions. The plants were evaluated for growth parameters such as shoot height, root length, root morphology (root surface, root diameter and volume), shoot and root dry weight, uptake of macro and micro mineral nutrients, root colonisation and mycorrhizal dependency. Mycorrhizal species significantly improved growth and productivity of sorghum genotypes. Inoculation of Funneliformis mosseae, Claroideoglomus claroideum and Claroideoglomus etunicatum resulted in the highest shoot and total dry matter biomass production in Ashana, Hereahri and Yellow genotypes, respectively. Mycorrhiza inoculated white genotype had higher root colonisation and root development, and shoot P, K, Ca and Mg contents. Yellow genotypes produced significantly higher shoot and total dry weight and also were highly mycorrhiza dependent among the four genotypes. Compared to the control treatment mycorrhizal inoculation increased shoot Zn concentration but had non-consistent effects on shoot Cu, Fe and Mn contents. Conclusively, our findings confirmed that sweet sorghum genotypes responded selectively to arbuscular mycorrhizal fungi (AMF) colonisation for their growth parameters and nutrients uptake.

Effect of Rhizobium Inoculation and Phosphate Rock Fertilizer Application on Biomass Production, Nutrient use Efficiency and Yield Parameters of Green Gram (Vigna radiata)

The research was focused on an ecologically sound and highly production of legumes particularly green gram through the application of Rhizobium and rock phosphate fertilizer. Therefore, biomass production, nutrient use efficiency and yield parameters were determined for two growing seasons (November 2019 - January 2020 and February - April 2020), at Chuka university horticultural research farm. Biological nitrogen fixation (BNF) in green grams can improve sustainable soil fertility management and increased production. In Kenya, green gram is a major source of food security particularly in Tharaka Nithi County. However, green gram yields are usually low due to low phosphorous and nitrogen levels of the soil. A factorial experiment of 2 x 2 x 2 was laid out in a randomized complete block design. There were three factors, varieties (N26-nylon and KS20-uncle), phosphate rock (0 and 30 kg P ha-1) and Rhizobium MEA 716 (0 and 100 g ha-1) making a total of eight treatments which were replicated three times. Soil sampling and analyses were done before planting and after harvesting of green grams. Data on grain yield, total dry biomass, shoot and root dry weights. Phosphorus use efficiency (PUE) and nitrogen use efficiency (NUE) were done. Data was analysed using Statistical Analysis Software (SAS). Significant means were separated using Least Significant Difference (LSD) at probability level of 5 %. Results for both wet and dry seasons indicated that variety KS20 under Rhizobium inoculation and phosphate rock fertilizer (R1P1V2) showed significantly (P<0.05) higher increase in shoot dry biomass (52.01 g plant-1), root dry biomass (7.60 g plant-1), total dry biomass (146.4 g plant-1), number of pods (84 plant-1) and yield (2158 kg ha-1). Also, there was significant (P<0.05) higher phosphorous use efficiency of 279.32 Kg/ha and nitrogen use efficiency of 1732 kg/ha in treatment R1P1V2 over other treatments. From these results it was concluded that variety KS20 (V2) performed better compared to N26 (V1) under combined application of Rhizobium and phosphate rock fertilizer. Hence, based on the findings, for sustainable and improved green gram production farmers in Tharaka Nithi County.

The Genetic Architecture of Nitrogen Use Efficiency in Switchgrass (Panicum virgatum L.).

Switchgrass (Panicum virgatum L.) has immense potential as a bioenergy crop with the aim of producing biofuel as an end goal. Nitrogen (N)-related sustainability traits, such as nitrogen use efficiency (NUE) and nitrogen remobilization efficiency (NRE), are important factors affecting switchgrass quality and productivity. Hence, it is imperative to develop nitrogen use-efficient switchgrass accessions by exploring the genetic basis of NUE in switchgrass. For that, we used 331 diverse field-grown switchgrass accessions planted under low and moderate N fertility treatments. We performed a genome wide association study (GWAS) in a holistic manner where we not only considered NUE as a single trait but also used its related phenotypic traits, such as total dry biomass at low N and moderate N, and nitrogen use index, such as NRE. We have evaluated the phenotypic characterization of the NUE and the related traits, highlighted their relationship using correlation analysis, and identified the top ten nitrogen use-efficient switchgrass accessions. Our GWAS analysis identified 19 unique single nucleotide polymorphisms (SNPs) and 32 candidate genes. Two promising GWAS candidate genes, caffeoyl-CoA O-methyltransferase (CCoAOMT) and alfin-like 6 (AL6), were further supported by linkage disequilibrium (LD) analysis. Finally, we discussed the potential role of nitrogen in modulating the expression of these two genes. Our findings have opened avenues for the development of improved nitrogen use-efficient switchgrass lines.

Nurse-target functional match explains plant facilitation strength

Functional trait combinations underlie assembly rules of plant communities. In harsh environments, facilitation is widespread but its strength varies greatly between pairs of interacting nurse-target plants. Here, we investigated whether functional traits of potential nurse and target species can jointly predict the sign and strength of their interactions. In order to estimate the facilitation strength for 60 nurse-target species combinations, we conducted field experiments in a seasonally dry tropical forest. We estimated eight key functional traits (canopy diameter, leaf C:N, leaf ∂C13, specific leaf area, number of months without leaves, wood density, hydraulic diameter and root volume) for 20 potential mature nurse species established under field conditions. For three target species, four key functional traits were estimated for seedlings grown in greenhouse conditions (total dry biomass, plant water content, root:shoot ratio, and apical growth rate). Our results showed that facilitation strength can be explained by the interaction between nurse and target traits. Facilitation increased when low SLA nurses interacted with targets investing in apical growth, thus acquisitive targets are benefited by the greater availability of resources left by conservative nurses. Facilitation also increased when nurses with lower values of leaf ∂C13 interacted with high root:shoot ratio targets, so early release of light and soil resources due to nurse earlier leaf loss benefits drought resistant targets. Besides, root volume of the nurse promoted facilitation, probably due to improvements on soil conditions. Functional trait match can shed light on plant community assembly rules and help promote ecosystem restoration and management.

Ex Vitro Simultaneous Acclimatization and Rooting of In Vitro Propagated Tamarillo Plants (Solanum betaceum Cav.): Effect of the Substrate and Mineral Nutrition

Plants propagated by seed do not ensure genetic uniformity and are sometimes infected with diseases. In Vitro micropropagation techniques are an alternative method to traditional cloning approaches for producing true-to-type and pathogen-free plants. However, due to the particularities of the in vitro environment, these plants face many challenges, often critical to their survival, to adapt to ex vitro conditions. In this context, four substrates and two types of mineral nutrition (quick-release (QRF) and controlled-release (CRF) fertilizers), as well as their absence were evaluated in the process of acclimatization of Solanum betaceum plants. Stomatal conductance (gs), chlorophyll content index (CCI), and dry biomass of roots, shoots, and entire plants were the parameters analyzed during the acclimatization. The best crop performance (gs, CCI, and dry biomass) were observed in substrates consisting of vermiculite plus the application of mineral nutrients through a CRF, proving that mineral nutrition has the greatest positive impact on the acclimatization process. In these conditions, plants were obtained with a total dry biomass being significantly higher (515.0 mg (QRF) and 635.9 mg (CRF) when compared to the total dry biomass of untreated plants (119.9 mg). The best conditions for this first experiment were replicated in a second test in order to assess the best fertilizer amount suited for plantlet growth. In this case, the best results were obtained with 0.4 g of CRF, in which plants showed a dry biomass of roots (542.7 mg) and a total dry biomass (594.5 mg), which was significantly higher than in the control (183.2 mg and 165.9 mg, respectively) or with other concentrations of CRF (0.8 and 1.6 g). A similar trend was found concerning the CCI (5.3) and gs (72.5 mmol m−2 s−1) in which 0.4 g CRF gave also the best results when compared with the control (without CRF) or with 0.8 g (4.7 and 56.2 mmol m−2 s−1) and 1.6 g (4.7 and 52.2 mmol m−2 s−1) treatments. In general, it was found that tamarillo plantlets acclimatized to 0.4 g of CRF had a faster initial growth and better performance (CCI and gs), with plants ready to go to the greenhouse/field more quickly, thus reducing the time to obtain suitable plants for the market and shortening the production cycle.

Three-season rotation of chicory-tobacco-peanut with high biomass and bioconcentration factors effectively remediates cadmium-contaminated farmland.

Traditional phytoremediation is one approach to remediate heavy metal pollution. In developing countries, the key factor in promoting practical application of phytoremediation in polluted soils is selecting suitable plants that are tolerant to heavy metals and also produce products with economic value. Therefore, a field experiment was conducted with a three-season chicory-tobacco-peanut rotation to determine effects on remediation of cadmium (Cd)-contaminated farmland in China. All crops had strong Cd accumulation capacity, with bioconcentration factors of 6.61 to 11.97 in chicory, 3.85 to 21.61 in tobacco, and 1.36 to 7.0 in peanut. Yield of total dry biomass reached 32.4 t ha-1, and the Cd phytoextraction efficiency was 10.3% per year. Aboveground tissues of the three crops accounted for 83.9 to 91.2% of total biomass in the rotation experiment. Cd content in peanut grain and oil met the National Food Safety Standard of China (0.5mgkg-1, GB 2762-2017) and the Food Contaminant Limit of the European Union (0.1mgkg-1, 18,812,006). Therefore, in addition to phytoremediation of Cd-contaminated soils, the chicory-tobacco-peanut rotation system can also produce economic benefits for local farmers.

Indigenous organic resources utilization, application methods and sowing time replenish soil nitrogen and increase maize yield and total dry biomass

Wise management of indigenous resources replenishes soil nutrients and improves crop productivity and soil sustainability. Three year consecutive experiments were performed in the framework of Farmers Field School (FFS) during 2012–2014. Organic nitrogen sources [animal-urine (AU), animal-manures (AM), and animal manure-compost (AMC) with two application methods [interior-application method (IAM) and exterior-application method (EAM)] and three sowing timing [early sowing (ES), late-sowing (LS), and timely sowing (TS)] were studied. One control plot in each replication was placed as a check. The results showed that among different sowing time, TS has higher grains year−1, 1000 grains weight, dry biomass, grain yield and harvest index (HI) than LS and ES. AM delayed silking and physiological maturation. A higher grains year−1, 1000 grains weight, grain yield, total dry biomass, and HI were observed with AMC than control plots. In application methods, the IAM has delayed the silking and physiological maturity as compared to EAM. Similarly, higher grains year−1, 1000 grains weight, grain yield, dry biomass, and HI were observed with IAM than EAM. In sowing timing, higher grain nitrogen (GN) was observed in TS. Higher GN produced by AMC and AU treated plots. AMC produced 10% higher GN than manures treated plots. The IAM produced higher GN than EAM. The AMC produced significantly higher soil N and statistically at par with AU treated plots. IAM applied AMC, maize grain yield was higher than the AU and AM. In conclusion, AMC and AU embedded in soil with TS can sustainably increase maize yield and soil productivity.

Arbuscular mycorrhizal fungus and organics substrates effect on bean plant morphology and minerals

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts that require a host plant (tramp) and support (substrates) to be applied as bio-fertilizers in agriculture. The objective of this study is to assess eight native AMF consortia of semi-arid zones (C1-ART, C2-GEC, C3-PAR, C4-VIE, C5-CUC, C6-SAC, C7-SAB, and C8-MUZ) and their reproduction response in three organic substrates: coffee pulp (CP), bovine manure (BM) and sugarcane bagasse (SB) on bean Phaseolus vulgaris. Plant height, stem diameter, number of leaves, root length, fresh and dry biomass, and mineral content in root were measured. The organic substrates (CP and BM) and C5-CUC and C8-MUZ consortia increased plant height, root length, and total fresh and dry biomass considerably. After day 75 of inoculation, root colonization oscillated from 5.7% in C8-MUZ to 46.1% in C2-GEC and C4-VIE; the greatest number of spores (201) was obtained in CP substrate in a 100-g sample. N, P, K, Ca, Mg, Fe, Zn, Cu, and Mn contents in root and leaves were signif icantly high (P ≤ 0.001). To conclude, native AMF inoculation and substrates had positive effects on biomass content and nutrient levels in leaf and root with the C2-GEC and C3-PAR consortia and CP and BM substrates, which produced better effects in beans, making them a biofertilization alternative in agricultural crops.

Do surfactants influence the growth of Rhizophora mangle during restoration of contaminated soil with emulsified oil?

Mangrove forests are ecosystems subject to contamination by oil spills. The objective of this study was to evaluate the development of Rhizophora mangle plants in soil contaminated with oil emulsified with surfactants. These ecosystems have diverse and economically valuable ecological functions. Mangrove soil and propagules were collected in southeastern Mexico. The propagules were sown under greenhouse conditions and the plants were grown for 3 months. Two bioassays were applied: (1) the soil was contaminated by oil emulsified with a biosurfactant synthesized by Azospirillum lipoferum, and (2) the soil was contaminated with oil emulsified with a surfactant based on pine essential oil. Emulsified oil was applied to the substrate in containers with 3‐month‐old plants until several concentrations were reached (0, 30,000, 40,000, 50,000, 60,000, and 70,000 ppm). Subsequently, 5 plants for each treatment were randomly extracted every 30 days for 12 months, and the stem length and diameter, root length, leaf area, and fresh and dry weights of the plants were evaluated. Plant development was evaluated through an analysis of variance and a test of means. At the end of the bioassay, the treatments with oil emulsified with pine oil yielded no surviving plants, whereas the treatments with oil emulsified with the biosurfactant yielded a 100% survival rate. Treatment with 30,000 ppm of oil emulsified with the biosurfactant yielded the greatest increases in the leaf area and total dry biomass. The heavy oil fraction concentration decreased by 93.9% with the 30,000 ppm treatment and by 82.64% with the 70,000 ppm treatment.

Dual inoculation with rhizobia and arbuscular mycorrhizal fungus improves water stress tolerance and productivity in soybean

A glasshouse experiment was conducted to understand the influence of rhizobia, Bradyrhizobium liaoningense and an arbuscular mycorrhizal fungus, Ambispora leptoticha on growth and yield performance of soybean cultivars, MAUS 2 and MAUS 212 (drought susceptible) and DSR 12 (drought tolerant) under different levels of moisture stress conditions. Three different water levels [100%, 75% and 50% FC] with three microbial inocula (B. liaoningense, A. leptoticha and B. liaoningense + A. leptoticha) served as main treatments and the water level treatments were imposed 31–45 days after sowing. Various growth, physiological and microbial parameters were recorded besides analysing the samples for nutrients. The results showed that the plant growth parameters like biovolume index, total dry biomass, root volume and seed yield were significantly higher in dual inoculated plants in all the cultivars at all the moisture levels. There was an increase in mean seed weight by 88% and dry biomass by 58% in dual inoculated plants compared to uninoculated plants. Further physiological parameters and nutrients level improved significantly with dual inoculation under stress condition. However significant difference in recorded parameters was not observed in plants grown at 100% and 75% FC suggesting dual inoculation of B. liaoningense + A. leptoticha is beneficial when stress is severe in all the 3 cultivars. The microbial and nutrient parameters followed the same trend. Further of the two drought susceptible cultivars, MAUS 2 performed better compared to MAUS 212 in all the studied parameters under stress with dual inoculation. The results therefore signify the importance of rhizobia and mycorrhizal inoculation for imparting stress tolerance in soybean.

Effects of indirect plant–plant interaction via root exudate on growth and leaf chemical contents in Rumex obtusifolius

ABSTRACT Belowground plant–plant interactions can affect the concentrations of leaf chemicals, but the mechanism is not clear. Here, we investigated the effects of intra- and interspecific root exudates on the growth and leaf chemical content of Rumex obtusifolius. Seedlings of R. obtusifolius were grown with exposure to root exudates collected from other R. obtusifolius plants or from Trifolium repens, Festuca ovina, or Plantago asiatica plants, and the total phenolic, condensed tannin, dry biomass, and chlorophyll contents of the leaves were examined. The root exudates from conspecific plants had no effect on the total phenolic, condensed tannin, and chlorophyll contents of the leaves but did significantly reduce the dry leaf biomass. Root exudates from heterospecific plants had different effects depending on the species. These results were different from the results of a previous study that examined the effects of direct plant–plant interaction in R. obtusifolius. Thus, indirect interaction via root exudates induces different effects in leaves from direct interaction.

Effect of Organic Amendments on the Water Stress Resistance of Corn Varieties during Vegetative Stage in Ultisols

Background: Water stress is one of the most crucial limiting factors in maize production on Ultisols. One solution that could be adopted to solve this problem is applying organic soil amendment. Methods: This study evaluated three varieties of corn: NK-Jumbo, Srikandi Kuning and Lamuru. The water stress treatment consists of 75% field capacity (without water stress) and 37.5% field capacity (water stress treatment). The organic amendment consists of without soil amendment, rice-straw 10 tons ha-1, biochar 10 tons ha-1 and rice straw 5 tons ha-1 + biochar 5 tons ha-1. A factorial, completely randomized design was used in this research. Result: Water stress and organic amendments affect total stomata, leaf curl, leaf area, proline content, shoot and root dry weight, shoot-root ratio and biomass production of corn. Applying organic amendments increases corn’s resistance to water stress, indicated by decreased plant proline content and increased biomass. The proline content of corn by application of organic amendment with rice straw 5 tons ha-1 + biochar 5 tons ha-1 (70.41 µ mol/g) was lower than the proline content of treatment without amendments (93.69 µ mol/g). NK-Jumbo was the most resistant variety to water stress conditions.

Wheat (Triticum aestivum L.) Yield and Yield Components as Influenced by Herbicide Application in Kaffa Zone, Southwestern Ethiopia

In order to identify the effect of herbicidal weed control practices on yield components and yield of wheat, the study was conducted at Kocha kebele in Chena district of Kaffa zone, Southwestern Ethiopia. 2,4-D amine salt (0.5 kg ha−1, 1 kg ha−1, and 1.5 kg ha−1) supplemented with one hand weeding 30 days after chemical application, clodinafop-propargyl 6% + fluroxypyr 12% (0.5 kg ha−1, 0.75 kg ha−1, and 1 kg ha−1) supplemented with one hand weeding 30 days after chemical application, pyroxsulam (0.4 kg ha−1, 0.5 kg ha−1, and 0.6 kg ha−1) supplemented with one hand weeding 30 days after chemical application, 2,4-D amine salt at 1 kg ha−1, clodinafop-propargyl 6% + fluroxypyr 12% at 0.75 kg ha−1, pyroxsulam at 0.5 kg ha−1, two hand weeding 30 and 45 days after crop emergence, weed-free check, and weedy check (unweeded) were the weed control treatments. Fifteen treatments were used for the trial and arranged in a randomized complete block design with three replications. The treatments had a significant effect on weed community, dry matter of weeds, parameters on weed control, phenology and growth parameters, and yield components and yield of wheat. The minimum total weed dry biomass was recorded in plots treated with clodinafop-propargyl 6% + fluroxypyr 12% at 1 kg ha−1 + one hand weeding at crop harvest. The highest weed control efficiency (93.30%) and herbicide efficiency index (27.06%) and the lowest weed index (14.18%) were recorded with the application of clodinafop-propargyl 6% + fluroxypyr 12% at 1 kg ha−1 + one hand weeding. Higher number of grains per spike (57.9), 1000-grain weight (39.4 g ha−1), grain yield (3635.6 kg ha−1), biological yield (9004 kgha−1), and harvest index (40.23%) were recorded with the application of clodinafop-propargyl 6% + fluroxypyr 12% at 1 kg ha−1 + one hand weeding 30 days after chemical application, next to weed-free check. Managing weeds with the application of clodinafop-propargyl 6% + fluroxypyr 12% at 1 kg ha−1 + one hand weeding contributed maximum (50,745.2 ETB) net benefit. The application of clodinafop-propargyl 6% + fluroxypyr 12% at1.0 kg ha−1 plus one hand weeding can be recommended to acquire high grain yield of wheat and high economic return in the study site.

Effect of Chitosan-Poly(Acrylic Acid) Complexes and Two Nutrient Solutions on the Growth and Yield of Two Habanero Pepper Cultivars

Chitosan (CS) is a natural polymer used in agriculture as a biostimulant that has been evaluated in different plant models. In this study, we evaluated the effect of the foliar application of chitosan–poly(acrylic acid) complexes (CS–PAA) and two nutrient solutions (A and B) on the parameters of growth and yield of two habanero pepper cultivars (Chichen Itza and Jaguar) in a greenhouse. Over the course of the experiment, eight foliar applications were carried out at 15-day intervals. Our results showed that foliar applications of CS–PAA complexes have a biostimulant effect on the habanero pepper crop by increasing the total dry biomass of the plant and the number of fruits of the two cultivars. Regarding nutrient solutions, the nutrient solution A increased the yield of the Chichen Itza cultivar; this effect was because it had a better balance of potassium and calcium compared to the nutrient solution B. These results provide advances on the use of CS–PAA complexes as a biostimulant and the management of nutrient solutions in the crop of habanero peppers.

Estimation of the total dry aboveground biomass in the tropical forests of Congo Basin using optical, LiDAR, and radar data

ABSTRACT In this investigation, optical (SPOT-7 NAOMI), airborne LiDAR, and PolInSAR L-band data, along with forest inventories, were employed to develop models for estimating total dry aboveground biomass (AGB) over the tropical forests in the Congo Basin (Gabon) of Central Africa. Remote sensing-based variables like texture (from SPOT), median canopy height (from LiDAR), and backscattering coefficient along with canopy surface heights (from PolInSAR) were used to estimate the AGB. These variables were used individually (or combined) to develop the AGB models based on the multivariate adaptive regression splines (MARS) approach. Validation indicated that in case of the single variable models, the LiDAR-based model yielded the lowest estimation root-mean-square error (RMSE = 28%). The error decreased further when the median canopy height was combined with the texture or with the radar variables (RMSE <25%). The texture derived from the Fourier transform textural ordination (FOTO) approach was more effective in improving the results as compared to the gray level co-occurrence matrices (GLCM) approach. Model validation indicated that the best performance in AGB estimation was achieved by combining optical, LiDAR, and radar data (R2 = 0.89 and RMSE = 24%).

Phytoremediation of soils contaminated with crude and weathered oil using two rice varieties (Oryza sativa L.)

Objective: To evaluate the potential for soil phytoremediation with new and weathered hydrocarbons with two rice varieties (Oryza sativa L.). Materials and Methods: The assessed treatments were 150 mg kg-1 (control soil), 30,000; 60,000 and 90,000 mg kg-1 of new oil and 79,457 mg kg-1 of weathered oil 1 and 42,000 of mg kg-1 of weathered oil 2; they were established in a completely randomized design with 6 x 3 factorial, with four repetitions each. The evaluated variables were populations of total bacteria (colony forming units CFU per grams of dry soil), free-living nitrogen-fixing bacteria (CFU), total fungi (CFU), and total dry biomass (g). Total bacteria and fungi were quantified at the beginning of the experiment at 90 and 145 days. Results: The highest total petroleum hydrocarbons (HTP) degradation was 73 and 72 % in the 79,457 and 42,000 mg kg-1 concentrations of weathered HTP 1 and 2, in the rhizosphere of rice silver line 21. The total dry biomass reported significant differences (p ≤ 0.05), evidencing a lower effect in the 60,000 mg kg-1 concentration in new oil, which caused a 33 % reduction compared to the control. Results/Conclusions: The rice variety line 21 has a greater potential to phytoremediate soils contaminated with crude and weathered oil in field conditions in tropical areas.