Growth Yield Research Articles

Time-Varying Effects of Extreme Weather Shocks on Output Growth of the United States

This study investigates the impact of a structural shock to a metric of extreme weather, identified using sign restrictions, on output growth (and inflation) in the United States (US) from 1961 to 2022, using a new class of time-varying parameter vector autoregressive (endogenous TVP-VAR) model, whereby the identified structural innovation is allowed to influence the dynamics of the coefficients in the model unlike in traditional TVP-VARs. Our results provided evidence that severe weather shocks adversely affect output growth (and inflation) over the forecast horizon of one- to twelve-quarter-ahead. More importantly, we find that the effect of extreme weather on the US macroeconomic variables is indeed time-varying, with the impacts becoming smaller in recent times, possibly due to improved adaptation to climate change.

Comparative Study of Ginger Cultivars under Shading Conditions in a High Tunnel

Ginger (Zingiber officinale Rosc.) is a valuable sciophyte crop used as a spice or fresh herb in culinary dishes and for treating medical issues such as osteoarthritis, neurological diseases, vomiting, and asthma. The demand for ginger in the United States is remarkably high; it is produced commercially and exclusively in Hawaii but can only meet ∼20% of US demand. Light for ginger growth may be more important than is often assumed, but the roles of light in ginger growth and rhizome yield are not fully understood. We hypothesized that artificial shade would produce the highest yielding ginger compared with no shade. This study evaluated the impact of different shading suited for ginger growth and rhizome yield of different cultivars grown in a high tunnel. There were three levels (0%, 22%, and 40%) of shade using RCBD design. We analyzed the overall yield (weight) of ginger and the specific yield (weight) of different rhizome parts (biological root, edible root, and seed ginger) per plant in addition to plant growth data. Data were analyzed for 2018 and 2019, and shade conditions influenced ginger growth and yield. There was no significant difference between shade conditions or cultivars, but general trends found that data differed between the two growing seasons. In 2018, Chinese White and Hawaii Yellow produced a better (higher) yield under 0% and 40% shade. However, in 2019, Chinese White and Hawaii Yellow produced the highest total yield under 22% shade, but Bubba Blue produced the highest overall yield at 0% shade.

Integration of organic manures and inorganic fertilizers on soil properties at different growth stages and yield of paddy in coastal saline soil of Maharashtra

Integration of organic manures and inorganic fertilizers on soil properties at different growth stages and yield of paddy in coastal saline soil of Maharashtra

Enhancing yields of Pleurotus ostreatus and Lentinula edodes mushrooms using water hyacinth (Eichhornia crassipes [Mart.] Solms) supplemented with locally available feedstock as substrate

This study assessed the performance of Pleurotus ostreatus and Lentinula edodes mushrooms on a variety of substrate combinations. Water hyacinth, rice husk, and cow dung were employed as substrates. Mushroom growth performance, yield, proximate composition, and mineral content were among the variables evaluated. The results indicate significant differences (p < 0.05) in spawn run duration, first harvest duration, total yield, and biological efficiency among the substrate combinations for the mushroom species. The substrate combination of 80% water hyacinth and 20% cow dung consistently exceeded the performances of others, demonstrating higher total yield (863.00 and 799.81 g/bag) and biological efficiency (88.51% and 82.03%) for P. ostreatus and L. edodes mushrooms, respectively. Proximate analysis results also demonstrated that this substrate combination produced mushrooms with higher protein (14.72 and 12.04%) and carbohydrate (55.11 and 58.05%) contents for P. ostreatus and L. edodes, respectively. P, K, Mg, Na, Ca, Fe, Zn, and Cd levels in P. ostreatus samples ranged from 1700 to 2700, 28100 to 39500, 1600 to 7800, 291.55 to 400.23, 310.37 to 372.70, 26.42 to 45.47, 61.87 to 70.40, and 1.13–1.25 mg/kg on average, respectively. The levels for P, K, Mg, Na, Ca, Fe, Zn, and Cd ranged from 19700 to 22700, 22500 to 25000, 2100 to 2500, 250.96 to 300.90, 284.66 to 296.19, 24.04 to 29.49, 74.03 to 83.98, and 1.31–1.45 mg/kg for L. edodes samples. The evaluated mushrooms grown on the various substrate combinations contain higher major and minor minerals needed in the human diet than toxic elements. This indicated that the evaluated edible mushrooms had high important mineral levels and could be considered a good source of vital elements. They are also very good at balancing nutrient supply scarcity, which is common in developing countries like Ethiopia. However, according to the World Health Organization's permissible limits for human intake, adequate attention and control of daily dietary intake is necessary for specific elements.

Effect of bioregulators on growth characteristics and yield of mung bean (Vigna radiata L.) under central plain zone of Uttar Pradesh

Effect of bioregulators on growth characteristics and yield of mung bean (Vigna radiata L.) under central plain zone of Uttar Pradesh

Salinity as an Abiotic Stressor for Eliciting Bioactive Compounds in Marine Microalgae.

This study investigated the impact of culture medium salinity (5-50 PSU) on the growth and maximum photochemical yield of photosystem II (Fv/Fm) and the composition of carotenoids, fatty acids, and bioactive substances in three marine microalgae (Chrysochromulina rotalis, Amphidinium carterae, and Heterosigma akashiwo). The microalgae were photoautotrophically cultured in discontinuous mode in a single stage (S1) and a two-stage culture with salt shock (S2). A growth model was developed to link biomass productivity with salinity for each species. C. rotalis achieved a maximum biomass productivity (Pmax) of 15.85 ± 0.32 mg·L-1·day-1 in S1 and 16.12 ± 0.13 mg·L-1·day-1 in S2. The salt shock in S2 notably enhanced carotenoid production, particularly in C. rotalis and H. akashiwo, where fucoxanthin was the main carotenoid, while peridinin dominated in A. carterae. H. akashiwo also exhibited increased fatty acid productivity in S2. Salinity changes affected the proportions of saturated, monounsaturated, and polyunsaturated fatty acids in all three species. Additionally, hyposaline conditions boosted the production of haemolytic substances in A. carterae and C. rotalis.

Biofortifying multiple micronutrients and decreasing arsenic accumulation in rice grain simultaneously by expressing a mutant allele of OAS-TL gene.

Rice grains typically contain relatively high levels of toxic arsenic (As) but low levels of essential micronutrients. Biofortification of essential micronutrients while decreasing As accumulation in rice would benefit human nutrition and health. We generated transgenic rice expressing a gain-of-function mutant allele astol1 driven by the OsGPX1 promoter. astol1 encodes a plastid-localized O-acetylserine (thiol) lyase (OAS-TL) with Ser189Asn substitution (OsASTOL1S189N), which enhances cysteine biosynthesis by forming an indissociable cysteine synthase complex with its partner serine acetyltransferase (SAT). The effects on growth, As tolerance, and nutrient and As accumulation in rice grain were evaluated in hydroponic, pot and field experiments. The expression of OsASTOL1S189N in pOsGPX1::astol1 transgenic lines enhanced SAT activity, sulphate uptake, biosynthesis of cysteine, glutathione, phytochelatins and nicotianamine, and enhanced tolerance to As. The expression of OsASTOL1S189N decreased As accumulation while increased the accumulation of multiple macronutrients (especially sulphur, nitrogen and potassium) and micronutrients (especially zinc and selenium) in rice grain in a pot experiment and two field experiments, and had little effect on plant growth and grain yield. Our study provides a new strategy to genetically engineer rice to biofortify multiple essential nutrients, reducing As accumulation in rice grain and enhancing As tolerance simultaneously.

Biofloc Technology in Improving Shellfish Aquaculture Production – A Review

Abstract Biofloc technology is instrumental in improving growth performance and yield in shellfish aquaculture, while leading to enhanced water quality through maintaining the nutrients level within a safe range. More specifically, toxic nitrogenous wastes are converted into beneficial microbial biomass known as “biofloc”, contributing to improve shellfish immune system. Among the various parameters affecting the efficiency of the process is the carbon source and C:N ratio. In light of these, the present work critically reviews the effects of biofloc systems on growth performance, immunity and diseases resistance in shellfish production. Moreover, it scrutinizes the microbial diversity and nutritional composition of biofloc. Then, the application of the technology in various shellfish cultures, including shrimp, freshwater prawn, crabs, crayfish, clam, and oyster, is presented. Overall, biofloc systems contribute to enhanced shellfish survival rate to the highest value of 96–100% for marine shrimp, 95–99% for freshwater prawn, 70–83% for crayfish, 83–100% for oyster, Crassostrea sp. and up to 2% for mud crabs larvae through substantially reducing the ammonia level in the culture (summarized in Table 1 – Table 5). Finally, the main challenges in utilizing biofloc systems, i.e., suitable aeration and mixing and microbial mechanisms involved are also explained to shed light on future research directions in the field.

Improving the simulation accuracy of summer maize growth and yield by pixel-based parameterization based on assimilating upscaled MODIS LAI

Accurately simulating maize (Zea mays L.) yield at the regional scale is of paramount importance for making informed policy adjustments and for ensuring food security. Sobol sensitivity analysis was used in this study to screen sensitive parameters of a process-based crop model (Chinese Agricultural Meteorological Model, CAMM). An upscaling approach was utilized to reduce the intra-pixel heterogeneity error of MODIS LAI. Then upscaled MODIS LAI data were assimilated into the CAMM model through a 4DVar assimilation algorithm to optimize pixel-level sensitive parameters, thereby improving the simulation accuracy of the summer maize growth process and yield. Specific leaf area (SLATB_0, SLATB_1) during the period from emergence to tasseling of summer maize exhibited the strongest impact on summer maize yield. Additionally, the average LAI value within the 85–95 % range of ordered LAI values for small pixels within large pixels effectively reduced the intra-pixel heterogeneity error of MODIS LAI, and pixel-based parameterization of SLATB_0 and SLATB_1 at a larger pixel scale (0.0625°) was achieved. Based on yields recorded at agrometeorological stations from 2015 to 2020, assimilated yields in both data assimilation scheme 1 (DA1, optimization of only the sensitive parameter SLATB_0) and scheme 2 (DA2, simultaneous optimization of sensitive parameters SLATB_0 and SLATB_1) exhibited higher accuracy than schemes without data assimilation (with r values of 0.41–0.72 and NRMSE values of 19–30 %). Furthermore, DA2 showed greater simulation accuracy (r: 0.64–0.93, NRMSE: 9–21 %) than DA1 (r: 0.61–0.91, NRMSE: 12–23 %). Upscaling remotely sensed LAI products can significantly reduce the uncertainties of LAI data at a larger pixel scale, and assimilating these LAI data into crop models can effectively increase the simulation accuracy of crop growth and development processes at the regional scale.

Potential of cattle urine as an alternative fertilizer for maize (Zea mays L.) production in Ethiopia

Maize productivity has been increasing through the years due to increased use of inorganic fertilizers. However, the price and environmental impact has brought lack of interest among the farmers. Thus, this study was aimed at evaluating the growth, yield and nitrogen use efficiency (NUE) of maize varieties under cattle urine application. The field experiment was conducted in randomized complete block design with three replications. The experiment consisted of four treatments viz. control, 100 and 50 % cattle urine and recommended dose of inorganic fertilizer. The results demonstrated a comparable growth and grain yield increment due to 100 % cattle urine and recommended dose of inorganic fertilizer. The difference between the two varieties in growth, yield and related traits, and NUE indices due to fertilizer applications was insignificant. The leaf area of maize nourished with 100, 50 % cattle urine and recommended dose of inorganic fertilizer increased by 11.15, 9.73 and 9.78 folds, respectively, in two months period relative to the controls. Fertilized plants had significantly (p < 0.05) higher grain yield (GY). The use of 100, 50 % cattle urine and inorganic fertilizers resulted in 526.76, 326.12, 542.91 % and 47.83, 36.03, 49.78 % increment in average GY and aboveground biomass, respectively, compared to controls. Similarly, plants fertilized with 50 % cattle urine showed an average GY reduction of 39.87 and 38.10 % compared to the recommended dose of inorganic fertilizer and 100 % cattle urine, respectively. The use of 50 % cattle urine produced significantly higher NUE, N agronomic efficiency (NAE), N recovery efficiency (NRE) and internal efficiency (IE). Higher GY kg-1 of N applied was obtained from cattle urine applications. In a nutshell, the results confirmed the potential of cattle urine as an alternative to inorganic fertilizers in maize production. However, further studies on optimization of the cattle urine rate and scale up works are recommended.

Intercropping salt-sensitive Solanum lycopersicum L. and salt-tolerant Arthrocaulon macrostachyum in salt-affected agricultural soil under open field conditions: Physiological, hormonal, metabolic and agronomic responses

Salinity is one of the important environmental risks affecting agricultural production in the world. Under this condition and with the conventional cultivation methods, glycophyte plants, like tomato, are subjected to many stresses, such as ion toxicity, osmotic stress, nutritional disturbance, oxidative damage and metabolic disorders, which cause growth inhibition and yield reduction. In this context, the main objective of our study was to compare the physiological, hormonal, metabolic and agronomic responses of tomato plants (Solanum lycopersicum L.) grown in monoculture (TM) or intercropping (TH) with the halophytic species Arthrocaulon macrostachyum in a salt affected soil. The results showed that the intercropping system (TH) reduced the soil electrical conductivity, and Na+ and Cl- contents, improving mineral nutrition in tomato plants compared to TM. In addition, TH decreased the osmotic stress, improved water potential and increased water use efficiency in tomato plants, whereas the integrity of gas exchange parameters were maintained; as a consequence, an increase in tomato yield was achieved. Moreover, the ratio of stress hormones (ABA, SA and JA) to growth regulating hormones (GA, auxins and cytokinins) decreased under TH. Metabolomic analysis showed clear defined patterns of differentially accumulated metabolites. Some of the metabolites with higher abundance in TH were linked to phenylpropanoid biosynthesis and phenylalanine metabolism, whereas alanine, aspartate and glutamate metabolism, monoterpenoid biosynthesis and butanoate metabolism pathways were downregulated. Our results support the importance of A. macrostachyum in the desalination of salt-affected soils and in the improvement of tomato yield in mixed culture. Indeed, this intercropping system offers farmers a low-cost biosolution that improves yields while respecting the environment.

Preparation and performance study of sludge biomass bamboo charcoal

Abstract The purpose of this study is to explore a new low-cost and high-efficiency biochar adsorption material. The residual sludge as solid waste and fresh bamboo with fast growth and high yield were used as raw materials, modified by the KOH chemical activation method, and pyrolyzed in a tubular furnace with nitrogen atmosphere to obtain sludge biomass bamboo charcoal. In the performance test, the H2S gas adsorption experiment in a fixed bed reactor and the heavy metal adsorption experiment in soil were designed. Using different proportions of biochar, the preparation process of biochar was optimized by adjusting the raw material ratio and activation conditions. The results showed that when dealing with H2S gas, the appropriate amount of sludge can improve the adsorption effect, while the increase of bamboo component will reduce the adsorption rate. In the soil Cr(VI) restoration experiment, it was found that the best restoration effect was achieved after adding 10% biochar and applying it for 28 days, and the restoration rate reached 63.5%.

Response of Hydroponic Tomato Yield and Yield-correlated Morphological Characteristics to Constant or Growth Stage-based Nutrient Management Strategies

In the United States, the annual revenue attributable to tomato production is $1 billion. However, tomato production can cause negative environmental impacts, such as water pollution, often in the form of eutrophication-causing nutrient pollution. Hydroponic production can decrease excess nutrient leaching; however, optimization of nutrient management and cultivar choices could further decrease excess nutrient discharges. The objectives of this study were as follows: to evaluate and compare the responses of tomato growth characteristics, yield, and yield components to two nutrient management regimes (varying nutrient solution concentrations by growth stage and the use of a constant nutrient solution concentration from transplant to termination), and to analyze the effects of growth habits among six cultivars (Big Beef, Cherokee Purple, Heatmaster, Legend, Mountain Fresh Plus, and Tropic) on tomato yield and yield-correlated morphological characteristics. The nutrient management strategies were applied to tomato plants, and data regarding yield and related morphological characteristics were obtained. Data were analyzed using SAS PROC GLM. An analysis revealed no significant difference in the total fruit weight/plant between nutrient management regimes (P = 0.05); however, the mean fruit weight (164.26 g) and diameter (71.70 mm) were significantly greater (P &lt; 0.0001) for plants that received the constant concentration nutrient regime. Indeterminate plants had a significantly greater (P &lt; 0.0001) mean fruit weight (192.76 g) and mean fruit diameter (76.42 mm). Among cultivars, Big Beef had a significantly greater (P &lt; 0.05) total fruit weight/plant (9.25 kg). Applying a constant nutrient concentration to indeterminate cultivars, particularly Big Beef and Cherokee Purple, improved the factors analyzed and could decrease negative environmental impacts while increasing profits of the producers.

Effect of Regulated Deficit Irrigation on Cucumber Growth and Fruit Yield in Greenhouse Conditions

Effect of Regulated Deficit Irrigation on Cucumber Growth and Fruit Yield in Greenhouse Conditions

Biodegradation of glucose and paracetamol and process optimisation with open mixed microbial cultures in lab-scale sequencing batch reactors

In the context of biological wastewater treatment, this study investigated xenobiotics (man-made chemicals) biodegradation and process optimisation to maximise sustainability. Lab-scale sequencing batch reactors (SBRs) fed with paracetamol (model xenobiotic) and glucose (model biogenic substrate) each as only carbon source (feed concentration 1 g L−1) were run in a range of HRTs (hydraulic retention time, range 0.5–2 d) and SRTs (solids retention time, range 1–28 d). For both substrates, the removal of COD (chemical oxygen demand) increased as the SRT increased, reaching 97 % for glucose and 86 % for paracetamol. At the lowest HRT, the high solid losses with the effluent caused a reduction in the SRT with worse substrate removal. The fraction of the removed COD which was converted into biomass increased for lower SRT and overall the best performance for sustainability (compromise between substrate removal, energy consumption and plant footprint) was observed with HRT 1 d and SRT 11–12 d. The experimental data were modelled using two different approaches: linearisation of a continuous-flow model and non-linear parameter fitting with a periodic steady-state SBR model. The results indicated faster growth rate and slightly higher growth yield for glucose than for paracetamol.

Effects of Metribuzin on Soil Microbiome and Weed Management Under Varying Planting Practices and Potato Seed Dormancy

AbstractWeed infestation in potato field has become a major concern to smallholder farmers and environment, requiring sustainable intervention. This study aimed to determine (i) whether metribuzin application rate (0, 0.5, 1 (standard), 1.5, and 2 kg ai ha−1) has effects on soil microbes and soil nutrients in the short term using potted soil and (ii) the influence of potato seed dormancy (short; Shangi variety and long; Unica variety) and planting technique (surface, ridge, or furrow planting) on the efficacy of weed management practice (metribuzin (480 g L−1) herbicide and hoeing) in the field. Bacterial colony counts were recorded upon isolation from the potted soil. Soil nutrients were also analysed before and after metribuzin treatment. Data on crop growth (height and stem count), weed abundance, yield, costs, and revenues were recorded from a field experiment. Morphologically distinct bacterial strains were tested for Gram reaction and response to carbon utilization using analytical profile index kits (API 50 CH and 20 NE). In total, nine distinct bacterial strains were isolated and all were Gram positive, with variation in response to carbon substrates. Concentration of 2.0 kg a.i ha−1 significantly (p ≤ 0.05) reduced bacterial count in the first day, followed by an increase in the subsequent incubation days, while 1.0 and 1.5 kg a.i ha−1 concentrations had the highest colony development index and species richness. Significant effects of metribuzin on soil pH, total N, and total organic C in the short term were revealed. Notably, weedy plots had the highest Shannon weed index. Weeds reduced stem count and height growth by 57% and 62% respectively. Plots with Shangi had 9.8% lower weed count than those with Unica and hence higher yield was recorded from the former. While surface planting had the lowest weed control efficacy, crop growth attributes, and yield, furrow and ridge planting were not significantly different. Weed abundance and crop growth attributes in metribuzin and hand-hoed plots did not differ significantly, yet hoeing resulted in 5.30 t ha−1 above that obtained from plots managed using metribuzin. Higher dry matter and tuber yield were observed from hoed plots with Shangi planted in furrow or ridge. Use of metribuzin resulted in higher net benefit ratio and marginal rate of return than hand hoeing. The results reveal that use of metribuzin early and later in the potato growing phase can minimize weed infestation, but the efficacy depends on planting method and seed dormancy.

Influence of Iron and Zinc Biofortification on Growth and Yield of Drilled Rice (Oryza Sativa L.)

A field experiment was conducted during kharif 2022 and 2023 to study the effect of iron and zinc biofortification on the growth and yield of drilled rice (Oryza sativa L.) at Krushi Vigyan Kendra, Navsari Agricultural University, Dediapada, Gujarat. The experiment was laid out in a randomized block design with ten treatments. Based on pooled analysis, almost all the growth attributes (periodical plant height, number of tillers plant-1, leaf area, leaf area index and dry matter accumulation plant-1), yield attributes (productive tillers m-2, number of filled grains panicle-1, panicle length, weight of panicle and 1000 grain weight), grain yield (3035 kg ha-1) and straw yield (5336 kg ha-1) were recorded significantly higher under treatment T10 (soil ZnSO4 + FeSO4 each @ 25 kg ha-1 and foliar ZnSO4 + FeSO4 each @ 0.5% at 30 &amp; 60 DAS). Based on the results, it concluded that for achieving higher growth and yield in drilled rice, the crop should be fertilized with soil ZnSO4 + FeSO4 each @ 25 kg ha-1 and foliar ZnSO4 + FeSO4 each @ 0.5% at 30 &amp; 60 DAS along with RDF and soil ZnSO4 + FeSO4 each @ 25 kg ha-1 along with RDF.

Response of Two Cowpea Cultivars to Spraying with Moringa Leaf Extract and Jasmonic Acid in Growth Yield Components

A field experiment was conducted at the Research Station of the College of Agriculture, University of Kufa/Najaf, for the spring season of 2023, to determine the growth and yield response of two cowpea varieties to spraying with Moringa leaf extract and jasmonic acid (JA). The experiment included three factors, the first factor was two varieties of cowpea: American Ramshon and Dutch variety, the second factor was foliar spray with Moringa leaf extract at three concentrations of 0.2 and 4 g L-1, and the third factor was foliar spray with three concentrations of JA at 0, 10 and 20 mg L-1. The spraying was applied three times during the growing season, with an interval period of 14 days. The experiment was split-split-plots based on Randomized Complete Blocks Design (R.C.B.D) and three replicates. The results showed that the Dutch variety was significantly superior in the vegitative growth indicators, while the American cowpea Ramshon had the highest response in quantitative and chemical indicators, especially the total plant yield of green pods recording 7.470 tons ha-1 compared to 5.886 tons ha-1 for the Dutch variety. Spraying with Moringa leaf extract at a concentration of 4 g L-1 recorded significantly higher indicators in the shoot dry weight 65.59 g plant-1, number of pods 25.61 pods plant-1, and leaf and pods content of carbohydrates and protein 2.65 and 12.95%. On the other hand, foliar spray with JA at 20 mg L-1 recorded a significant increase in plant length 45.88 cm. Most of the studied indicators in the experiment recorded higher rates in the interaction treatment of the Dutch variety and spraying 4 g L-1 Moringa leaf extract and 10 mg L-1 of JA compared to all individual and interaction treatments.

Response of Two Cowpea Cultivars to Spraying with Moringa Leaf Extract and Jasmonic Acid in Growth Yield Components

A field experiment was conducted at the Research Station of the College of Agriculture, University of Kufa/Najaf, for the spring season of 2023, to determine the growth and yield response of two cowpea varieties to spraying with Moringa leaf extract and jasmonic acid (JA). The experiment included three factors, the first factor was two varieties of cowpea: American Ramshon and Dutch variety, the second factor was foliar spray with Moringa leaf extract at three concentrations of 0.2 and 4 g L-1, and the third factor was foliar spray with three concentrations of JA at 0, 10 and 20 mg L-1. The spraying was applied three times during the growing season, with an interval period of 14 days. The experiment was split-split-plots based on Randomized Complete Blocks Design (R.C.B.D) and three replicates. The results showed that the Dutch variety was significantly superior in the vegitative growth indicators, while the American cowpea Ramshon had the highest response in quantitative and chemical indicators, especially the total plant yield of green pods recording 7.470 tons ha-1 compared to 5.886 tons ha-1 for the Dutch variety. Spraying with Moringa leaf extract at a concentration of 4 g L-1 recorded significantly higher indicators in the shoot dry weight 65.59 g plant-1, number of pods 25.61 pods plant-1, and leaf and pods content of carbohydrates and protein 2.65 and 12.95%. On the other hand, foliar spray with JA at 20 mg L-1 recorded a significant increase in plant length 45.88 cm. Most of the studied indicators in the experiment recorded higher rates in the interaction treatment of the Dutch variety and spraying 4 g L-1 Moringa leaf extract and 10 mg L-1 of JA compared to all individual and interaction treatments.

Calibration and evaluation of a CROPGRO Perennial Forage Model for Brachiaria humidicola yield simulation under future climate in subhumid environments of Ethiopia

Crop simulation models can be employed to assess the impacts of climate change and aid in strategic planning and decision making regarding forage strategies. This study focused on calibrating and assessing the performance of the CROPGRO Perennial Forage Model in simulating Brachiaria humidicola yield under projected future climates for high and moderate representative concentration pathway (RCP) scenarios in the central and western subhumid regions of Ethiopia. The model was calibrated to accurately represent rainfed growth and biomass yield, using field data from the Debre Zeit and Bako Agricultural Research Centers. Climatic data, including rainfall, temperature and solar radiation, were sourced from weather stations, whereas future climate scenarios for the near future, mid-century and end-of-century periods were derived from the CORDEX Africa outputs under RCP 4.5 and RCP 8.5. The calibration process refined species parameters related to vegetative partitioning, and enhanced the d-statistic and reduced the root mean square error (RMSE) for herbage, leaf, stem and total biomass accumulation. Despite projected decreases in leaf biomass, stem biomass is projected to increase. In addition, there are projected increases in herbage and total biomass accumulation under elevated greenhouse gas concentrations and warmer temperatures. Ultimately, the projected climate under both RCPs had no significant effect on Brachiaria humidicola grass production in Ethiopia.