Value-addition of agricultural wastes for augmented cellulase and xylanase production through solid-state tray fermentation employing mixed-culture of fungi

Solid-state fermentation (SSF) was performed to evaluate the potential of agricultural residues for the production of cellulase and hemicellulase using individual and mixed cultures of Aspergillus niger and Trichoderma reseei. The maximum filter paper (FP) cellulase activity of 13.57 IU/gram dry substrate (gds), 22.89 IU/gds and 24.17 IU/gds and β-glucosidase activities of 21.69 IU/gds, 13.58 IU/gds and 24.54 IU/gds were obtained with wheat bran medium at 96 h incubation period with A. niger, T. reseei and mixed-cultures of A. niger and T. reseei, respectively. Mixed-culture SSF using rice straw supplemented with wheat bran in the ratio 3:2 resulted in higher FP cellulase, β-glucosidase, endoglucanase (CMCase) and xylanase activities, compared to the activities obtained using mono-cultures. Similarly, higher FP cellulase, β-glucosidase, CMCase and xylanase activities of 35.8 IU/gds (96 h), 33.71 IU/gds (96 h), 131.34 IU/gds (120 h) and 3106.34 IU/gds (120 h) were achieved in the tray fermentation using rice straw with wheat bran in the ratio of 3:2. Results of present investigation showed that higher cellulase activity and an optimal combination of cellulase and β-glucosidase can be achieved through mixed-culture SSF in trays. The approach of utilizing negative cost agricultural wastes through tray fermentation for cellulase and hemicellulase production is expected to serve the objectives of: (a) management of wastes which would otherwise cause environmental pollution problems; (b) production of hydrolytic enzymes at low cost and; (c) simple technique requiring no sophisticated instruments with practical applications.     

Solid state fermentation of agricultural wastes for endoglucanase production

The lignocellulosic biomass (especially agricultural wastes) is known to be an excellent carbon source for microbial enzyme production. In this paper, the cellulase production from lignocellulosic materials under solid state fermentation (SSF) was investigated. The effects of fermentation conditions, such as moisture content, initial pH, temperature, and composition of mixed substrate (wheat straw and wheat bran) on endoglucanase production by Aspergillus niger 38 were studied. With a moisture content of 74% a pH range of 4.5–5.5 on mixed substrate containing wheat straw:wheat bran of 9:1, 14.80 international units (UI) endoglucanase activity/ml were obtained in 96 h.     

Value added waste of Jatropha curcas residue: Optimization of protease production in solid state fermentation by Taguchi DOE methodology

The oil extraction of Jatropha curcas created the large amount of the by-product from its seeds. An application of solid-state fermentation (SSF) was considered to be of value to these raw materials. This study investigated the potential of a utilization of deoiled J. curcas seed cake as substrate for protease productions by Aspergillus oryzae. While various parameters for SSF was conventionally individually optimized, five parameters were simultaneously examined based on Taguchi method. The effect of three different levels of five factors, including moisture content of substrate, inoculums size, incubation temperature, type of porous substrate and incubation time were examined. The optimum conditions for the protease production by A. oryzae obtained from this experiment were 45% moisture content of substrate, 10% inoculums size, 30 °C incubation temperature, deoiled J. curcas seed cake mixed with cassava bagasse ratio 4:1 as porous substrate at 84 h of incubation time. By adjusting the conditions to these optimum levels, the protease production increased up to 4.6 times as many as the protease yield from the non-optimizing experiment. The use of statistical approach, Taguchi method, provided a satisfactory outcome in defining the optimum conditions for protease production by A. oryzae. Further, the utilization of deoiled J. curcas seed cake as substrate for SSF was proven as the suitable practice for this agricultural waste, in order to develop for an industrial use.     

Ethanol production from alkali- and ozone-treated cotton stalks using thermotolerant Pichia kudriavzevii HOP-1

In the present study, milled cotton stalks were subjected to alkali pretreatment with NaOH at 1-4% (w/v) concentrations at 121 °C for time ranging from 30 to 90 min. Ozone pretreatment was performed by passing 45 mg/L of ozone gas over 2 mm cotton stalks for 150 min at a flow rate of 0.37 L/min. The residual biomass from 4% alkali pretreatment for 60 min showed 46.6% lignin degradation accompanied by 83.2% increase in glucan content, compared with the untreated biomass. Hydrolysis of 4% alkali-treated and ozone-treated cotton stalks was conducted using enzyme combination of 20 filter paper cellulase units/gram dried substrate (FPU/g-ds), 45 IU/g-ds β-glucosidase and 15 IU/g-ds pectinase. Enzymatic hydrolysis of alkali-treated and ozone-treated biomass after 48 h resulted in 42.29 g/L glucose, 6.82 g/L xylose and 24.13 g/L glucose, 8.3 g/L xylose, respectively. About 99% of glucose was consumed in 24 h by Pichia kudriavzevii HOP-1 cells resulting in 19.82 g/L of ethanol from alkali-treated cotton stalks and 10.96 g/L of ethanol from ozone-treated cotton stalks. Simultaneous saccharification and fermentation of the alkali-treated cotton stalks after 12-h pre-hydrolysis resulted in ethanol concentration, ethanol yield on dry biomass basis and ethanol productivity of 19.48 g/L, 0.21 g/g and 0.41 g/L/h, respectively which holds promise for further scale-up studies. To the best of our knowledge, this is the first study employing SSF for ethanol production from cotton stalks.     

Carbohydrate degrading enzyme production by plant pathogenic mycelia and microsclerotia isolates of Macrophomina phaseolina through koji fermentation

The ability of hydrolytic enzyme production by two different isolates of Macrophomina phaseolina was studied on apple pomace as a substrate for solid state fermentation (SSF). Initial moisture level, temperature and fermentation period was optimized so as to achieve higher output. Among the two different isolates, microsclerotial (MphP) and mycelial (MphM), MphP was observed as a potential source of different hydrolytic enzymes as compared to MphM. MphP gave higher enzyme activities (IU/gram dry substrate (gds): filter paper cellulase (FPase) activity 196.21 ± 16.3 (120 h), carboxymethyl cellulase (CMCase) 279.34 ± 28.25 (72 h), β-glucosidase (BGL) 129.82 ± 12.41 (96 h), xylanase 2527.88 ± 46.15 (120 h), and amylase 2780.72 ± 38.13 (96 h), respectively at 70% (v/w) IML. The incubation temperature was also found to have impact on the enzyme production ability of Macrophomina strains. The higher enzyme activities were achieved (IU/gds) as follows FPase 276.13 ± 25.02 (40 °C, 120 h), CMCase 278.11 ± 24.47 (35 °C, 144 h), BGL 189.47 ± 15.05 (30 °C, 144 h), xylanase 3845.77 ± 43.38 (35 °C, 144 h) and amylase activity of 3309.45 ± 29.22 (35 °C, 120 h), respectively using MphP at 70% (v/w) IML. This study reports for the first time the potential of carbohydrate degrading enzyme bioproduction by different isolates of M. phaseolina.     

Association between line per se and hybrid performance under excessive soil moisture stress in tropical maize (Zea mays L.)

Excessive moisture (EM) stress during the summer–rainy season is one of the major production constraints for maize (Zea mays L.) in large areas of South and South-East Asia. A key question in breeding for tolerance to excessive moisture is the extent to which the performance of maize hybrids can be predicted on the basis of per se performance of inbred lines under excessive moisture. We attempted to identify the relationship between morpho-physiological traits and grain yield measured on inbred parents and their single cross progenies under EM stress. Responses of various morpho-physiological traits, except days to 50% anthesis, differ significantly under normal versus EM stress. Superiority of hybrid progenies over parental inbred lines increased under EM stress, suggesting that hybrids were comparatively more tolerant to EM stress than inbred progenies. Across moisture regimes, all morpho-physiological traits of hybrids, except lodging and root porosity under normal moisture, were found to be positively and significantly correlated with mid-parent traits. Our data suggest that per se performance of lines was a relatively more important factor in determining hybrid performance under EM stress, while under optimum soil moisture conditions mid-parent heterosis was relatively more important than per se performance of mid-parent. Phenotypic correlation between hybrid and mid-parent yields showed a strong relationship under EM stress (r = 0.66^**). The relationship was statistically significant under normal moisture as well, though it was comparatively weak (r = 0.41^*). Our findings suggest that performance of hybrid progenies under excessive moisture can be predicted and improved to some extent on the basis of their inbred parents that have been systematically selected and improved for EM stress.     

Optimization of ethanol production by Saccharomyces cerevisiae UFPEDA 1238 in simultaneous saccharification and fermentation of delignified sugarcane bagasse

Ethanol production by Saccharomyces cerevisiae UFPEDA1238 was performed in simultaneous saccharification and fermentation of delignified sugarcane bagasse. Temperature (32 °C, 37 °C), agitation (80; 100 rpm), enzymatic load (20 FPU/g cellulose and 10%, v/v β-glucosidase or 10 FPU/g cellulose and 5% β-glucosidase) and composition of culture medium were evaluated. Ethanol concentration, enzymatic convertibility of cellulose and volumetric productivity were higher than 25 g/L, 72% and 0.70 g/L h, respectively, after 30 h, when the culture medium 1 and 20 FPU/g cellulose/10%, v/v β-glucosidase or the culture medium 2 and 10 FPU/g cellulose/5% β-glucosidase were used in SSF at 37 °C and 80 rpm. In the SSF with culture medium 2 (supplemented with ammonium, phosphate, potassium and magnesium), 150 L ethanol/t bagasse was achieved, with minimum enzyme loading (10 FPU/g cellulose and 5%, v/v β-glucosidase) for 8%, w/v of solids, which is often an important requirement to provide cost-efficient second generation ethanol processes.     

Heat and mass transfer studies of palm kernel cake (PKC) in fluidized bed fermenter

Solid state fermentation (SSF) which involves the growth of microorganism on moist solid substrates in the absence of free flowing water, has gained renewed attention over submerged fermentation for specific applications. During the SSF process in fermenter, there are three main engineering problems encountered such as the removal of metabolic heat from the substrate, diffusion of O₂ and moisture through the substrate, and heterogeneity of the substrate and inoculum. A fluidized bed fermenter in which the particles move independently like a fluid was proposed to conduct the study. Throughout the study, rapid heat transfer from PKC to air was experimentally observed within the first 150 s with a temperature drop of 30 °C. This indicated that the excellent heat transfer between palm kernel cake and air allows solid state fermentation of PKC without accumulation of metabolic heat in the fermenter. Apart from heat removal, water adsorption study on PKC from air to bed was carried out. It showed that the increase of adsorbed water in PKC was proportional to air relative humidity and inversely proportional to superficial air velocity. The maximum moisture content adsorbed by PKC under fluidization conditions was around 10% (on dry basis). Finally, mathematical models for heat and mass transfer were proposed which can predict the experimental data quite satisfactorily.     

Modeling of desorption of Alfalfa (Medicago sativa) stems and leaves

The equilibrium moisture content of agricultural products is necessary to optimize drying process and helps to keep the quality of the product during the period of storage. The main aim of this research was to find the best model which could define well, the exchange of moisture between alfalfa (Medicago sativa) and the surrounding air. The desorption isotherms of alfalfa (stem and leaf) were determined separately by using the saturated salt solutions method at three temperatures (25, 50 and 70 °C) within a range of 5-90% relative humidity. Experimental curves of desorption isotherms were fitted to modified equations of Henderson, Halsey, Oswin and Chung-Pfost as well as the GAB model and then evaluated visually by using residual plots and also by some statistical error parameters. The modified Halsey model was found to be the most suitable for describing the relationship between equilibrium moisture content, relative humidity and temperature.     

Characterizing leaf gas exchange responses of cotton to full and limited irrigation conditions

Plant responses to water deficit need to be monitored for producing a profitable crop as water deficit is a major constraint on crop yield. The objective of this study was to evaluate physiological responses of cotton (Gossypium hirsutum) to various environmental conditions under limited water availability using commercially available varieties grown in South Texas. Soil moisture and variables of leaf gas exchange were measured to monitor water deficit for various varieties under different irrigation treatments. Lint yield and growth variables were also measured and correlations among growth parameters of interest were investigated. Significant differences were found in soil moisture, leaf net assimilation (A_n), stomatal conductance (g), transpiration rate (T_r), and instantaneous water use efficiency (WUE_i) among irrigation treatments in 2006 while no significant differences were found in these parameters in 2007. Some leaf gas exchange parameters, e.g., T_r, and leaf temperature (T_L) have strong correlations with A_n and g. A_n and WUE were increased by 30–35% and 30–40%, respectively, at 600 μmol (CO₂) m⁻² s⁻¹ in comparison with 400 μmol (CO₂) m⁻² s⁻¹. Lint yield was strongly correlated with g, T_r, WUE, and soil moisture at 60 cm depth. Relative A_n, T_r, and T_L started to decrease from FTSW 0.3 at 60 cm and FTSW 0.2 at 40 cm. The results demonstrate that plant water status under limited irrigation management can be qualitatively monitored using the measures of soil moisture as well as leaf gas exchange, which in turn can be useful for describing yield reduction due to water deficit. We found that using normalized A_n, T_r, and T_L is feasible to quantify plant water deficit.     

Utilization of pretreated bagasse for the sustainable bioproduction of cellulase by Aspergillus nidulans MTCC344 using response surface methodology

Response surface methodology (RSM) was used to optimize the conditions for the production of endo β-1,4 glucanase, a component of cellulase by Aspergillus nidulans MTCC344 under solid state fermentation, using bagasse as the chief substrate. A four-factor-five-level central composite design was employed for experimental design and analysis of the results. Maximum cellulase activity (CMCase was 28.96 U g⁻¹) can be attained at the optimum conditions, 16.8 mm bagasse bed height, 60% moisture content, pH 4.25 and temperature 40 °C in the solid state fermenter. These data were rather close to the experimental results obtained (CMCase was 28.84 U g⁻¹). A. nidulans MTCC344 was able to hydrolyze pretreated bagasse completely after 8 days of incubation with significant endo β-1,4 glucanase activities. The results of Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) of bagasse showed structural changes through pretreatment, in favor of enzymatic hydrolysis. Bagasse with alkali pretreatment using sodium hydroxide is a source of lignocelluloses able to improve the yield of endo β-1,4 glucanase by the strain of A. nidulans. The endo β-1,4 glucanase produced during the bioconversion of cellulose to glucose by A. nidulans MTCC344 is strongly dependent on the pretreatment given before hydrolysis.     

Optimization of switchgrass and extruder parameters for enzymatic hydrolysis using response surface methodology

Switchgrass is an important biomass that can be hydrolyzed to yield fermentable sugars through pretreatment, which is the primary and expensive step in conversion of biomass to bio-ethanol. Most of the pretreatment operates in batch mode, which is energy intensive, requires high capital, results in decomposition of hemicellulose, and formation of inhibitors. Considering these shortcomings, a novel biomass pretreatment method using a high shear bioreactor could be a viable continuous one. The current study was undertaken to determine the effect of biomass parameters such as moisture content (10, 20, 30, 40, and 50% wb) and particle size (2, 4, 6, 8, and 10 mm) over a range of barrel temperature and screw speed (45-225 °C and 20-200 rpm). Statistical analyses revealed that among the independent variables considered temperature, screw speed, and moisture content had significant effect on sugar recoveries. Proposed quadratic model to predict glucose, xylose, and combined sugar recoveries from switchgrass had a high F and R² values indicating that the model has the ability to represent the relationship among the independent variables studied. The optimum pretreatment condition of barrel temperature 176 °C, screw speed 155 rpm, moisture content 20% wb, and particle size 8 mm resulted in maximum glucose, xylose, and combined sugar recoveries of 41.4, 62.2 and 47.4%, respectively. The optimum pretreated switchgrass had 50% higher surface area than that of the control.     

Evaluation of Fusarium oxysporum as an enzyme factory for the hydrolysis of brewer's spent grain with improved biodegradability for ethanol production

Brewer's spent grain (BG), the most abundant brewing by-product, is used in the present study as a low-cost feedstock for the production of ethanol by the mesophilic fungus Fusarium oxysporum using a consolidated bioconversion process. The production of required cellulolytic and hemicellulolytic enzymes was optimized under solid-state cultivation (SSC) concerning carbon source and initial moisture. The optimal medium contains BG and corn cobs (CC) in a ratio 7:3 while the optimal initial moisture is 66% (w/w). SSC in a laboratory horizontal bioreactor using the optimized medium allowed the large-scale production of a multienzymic system including endoglucanase, cellobiohydrolase, β-d-glucosidase, xylanase, feruloyl esterase, acetyl esterase, β-d-xylosidase and α-l-arabinofuranosidase. Chromogenic (fluorogenic) 4-methylumbelliferyl substrates were used to partially characterize the extracellular proteome of the microbe after the separation by isolectric focusing (IEF) electrophoresis. Alkali pretreatment of brewer's spent grain and different aeration levels were studied for the optimization of the ethanol production by F. oxysporum in a consecutive submerged fermentation. A yield about 65 g ethanol kg⁻¹ of dry BG was obtained with alkali pretreated BG under microaerobic conditions (0.01 vvm) corresponding to 30% of the theoretical yield based on total glucose and xylose composition of BG.     

Thin-layer drying kinetics and quality changes of sweet sorghum stalk for ethanol production as affected by drying temperature

The chopped sweet sorghum stalk was thin-layer-dried for long-term storage and ethanol production. The drying kinetics and the effects of drying temperature on the qualities of sweet sorghum stalk were investigated in this work. The results showed that the drying process could be simulated well by Wang and Singh's model. The diffusivity constant (D₀) and active energy (E_a) were estimated as 4.4 × 10⁻⁵ m²/s and 21.4 kJ/(mol K) for drying the chopped fresh stalk. According to the sugar composition, browning degree, and fermentability of the dried stalk obtained at various temperatures, the approximate drying temperature could be suggested as 50-60 °C for application. In this range, the moisture of the chopped fresh stalk could drop below the safe moisture for storage in 7-5.5 h with 12.1-9.7% total sugar loss during the drying process.     

Bacillus subtilis SPB1 biosurfactant: Production optimization and insecticidal activity against the carob moth Ectomyelois ceratoniae

Bacillus subtilis SPB1 was shown to produce a lipopeptide biosurfactant. The insecticidal activity of this biosurfactant was evaluated against Ectomyelois ceratoniae Zeller, a moth pest of stored dates in Tunisia. The LC₅₀ and LC₉₀ values after six days of contact were 152 μg/g and 641 μg/g, respectively. To promote an economical production of this highly effective bioinsecticide, statistical experimental designs and response surface methodology were employed to optimize the concentrations of agro-industrial residues and humidity, for lipopeptide biosurfactant production by B. subtilis SPB1 under solid state fermentation. The optimal medium leading to a production yield near to 28 mg of crude lipopeptide preparation per g of wet solid material was composed of a mixture of 4.34 g of tuna fish flour and 5.66 g of potato waste flour with a moisture content of 76%.     

Synthesis of withanolide A depends on carbon source and medium pH in hairy root cultures of Withania somnifera

Withania somnifera (L.) Dunal. (Indian ginseng) is an important medicinal plant which yields pharmaceutically active compounds called withanolides. The present work deals with optimization of parameters of hairy root culture of W. somnifera for the production of biomass and withanolide A. We also investigated the effects of carbon source [sucrose, glucose, fructose, maltose, glucose + fructose (1:1), fructose + sucrose (1:1) and sucrose + glucose (1:1)], sucrose concentration (1%, 2%, 3%, 4%, 6% and 8%) and the initial medium pH (4.0, 4.5, 5.0, 5.5, 5.8, 6.0 and 6.5) on growth and production of withanolide A in hairy root cultures of W. somnifera. We found that biomass accumulation and production of withanolide A was highest when sucrose was used as the carbon source (11.92 g l⁻¹ DW and 11.96 mg g⁻¹ DW of withanolide A). Further 3% sucrose concentration was found to be optimal for biomass accumulation (11.92 g l⁻¹ DW) and 4% sucrose favoured the production of withanolide A (13.28 mg g⁻¹ DW) in the tested range of concentrations (1-8%). The biomass of hairy roots was optimal when the initial medium pH was 5.8 (12.1 g l⁻¹ DW) and the withanolide A production was highest in the medium pH set at 6.0 (13.84 mg g⁻¹ DW).     

Biomass sorghum production and components under different irrigation/tillage systems for the southeastern U.S.

Renewable energy sources are necessary to reduce the U.S. dependence on foreign oil. Sorghum (Sorghum bicolor L.) may be a reasonable alternative as an energy crop in the southern U.S. because it could easily fit into existing production systems, it is drought resistant, and it has large biomass production potential. An experiment was conducted to evaluate several types of sorghum as bioenergy crops in Alabama: grain sorghum - NK300 (GS), forage sorghum - SS 506 (FS), and photoperiod sensitive forage sorghum - 1990 (PS). These sorghum crops were compared to forage corn (Zea mays L.) - Pioneer 31G65 in 2008 and 2009 with and without irrigation, and under conventional (total disked area, 0.15 m deep) and conservation tillage (in-row subsoiling, 0.30 m deep) in a strip-split-plot design. The parameters evaluated were: plant population (PP), plant height (PH), sorghum/corn aboveground dry matter (ADM), biomass moisture content (ABMC), and biomass quality (holocellulose, lignin, and ash). Sorghum had greater ADM than corn; however, corn had lower ABMC than sorghum. Lodging was observed in PS and FS, probably due to high plant populations (>370,000 plants ha⁻¹). Irrigation affected ADM positively in both years, but conservation systems improved ADM production only in 2009. Holocellulose, lignin, and ash variation differed significantly among crops but were lower than 8.3%, 2.0% and 1.9%, respectively, for both years and considered minor. Under conditions of this study, PS was considered the best variety for ADM production as it yielded 26.0 and 30.1 Mg ha⁻¹ at 18 and 24 weeks after planting (WAP).     

Path analysis for selection of drought tolerant sugarcane genotypes through physiological components

Water deficit is among the main environmental factors limiting agricultural productivity of sugarcane in Northeast Brazil by affecting virtually every aspect of plant growth, with consequent reduction of the agro-industrial productivity of this crop. This study aimed to use path analysis to evaluate the physiological components of sugarcane under two water conditions, with photosynthesis as the basic variable, in order to obtain subsidies that can help the genetic breeding of this crop by selection of superior clones with drought tolerance. The experiment was carried out in a greenhouse with a completely randomized experimental design, 4 × 2 factorial arrangements (four sugarcane genotypes × two soil moisture regimes: control, with 80-100% available water and stressed, with 0-20% water available) and with four replications. Each plot consisted of one pot with 12 kg of substrate containing one plant. Treatments were maintained at a humidity close to field capacity with daily replacement of the evapotranspired water with a water supply for 66 days of cultivation for treatments under stress. Evaluations were conducted on the fourth day after severe water stress at 70 days of cultivation. Data from nine physiological variables were considered, with six of these being used in the model after exclusion of those that were contributing to multicollinearity. Variables used in path analysis were enough to explain the variation found in photosynthesis under both water conditions. Stomatal conductance, transpiration and the SPAD index should be considered as a priority in breeding programs for sugarcane aiming to get more productive and tolerant genotypes to water stress, and selection indexes should be used with due consideration of these variables to promote gains in photosynthesis.     

Potato growth with and without plastic mulch in two typical regions of Northern China

Plastic film mulching is an important agricultural practice to save water and improve crop productivity in Northern China. Three field experiments were conducted to examine the effect of plastic mulch on soil temperature, potato (Solanum tuberosum L.) growth and evapotranspiration under drip irrigation in two typical regions of Northern China in 2001 and 2006. Results suggest that daily mean soil temperature under mulch was 2–9 °C higher than without mulch, especially during the early growth. Potato growth was restrained under mulching conditions in the North China Plain mainly due to the higher air temperature in this region and thus the higher soil temperature. The negative effects of mulching included a lower emergence and fewer marketable tubers per plant. Evapotranspiration and potato tuber yield were both reduced by mulch, especially in the North China Plain. In northwest China, mulch favorably increased the weight of jumbo tubers (W ≥ 300 g) per plant. Mulching duration had little effect on potato evapotranspiration in northwest China. However, both tuber yield and water use efficiency (WUE) decreased with increases in mulch duration, which suggests the plastic mulch should be removed early.     

Association between aflatoxin contamination and drought tolerance traits in peanut

The current study investigates the association between drought tolerance traits and aflatoxin contamination in peanut grown under long-term drought. Two field experiments were conducted at Khon Kaen University, Thailand using a split–split plot design with three drought stress levels as main plots, 11 genotypes as sub-plots, and two soil inoculations of Aspergillus flavus treatments as sub-sub-plots. The effects of temperature, soil moisture and A. flavus population on kernel colonization and aflatoxin contamination, and drought tolerance traits viz. specific leaf area (SLA) and root length density (RLD) were measured. The results demonstrated that elevated soil temperatures and reduced soil moisture, favored aflatoxin production. Drought in combination with higher levels of A. flavus inoculum load in the soil resulted in an increase in the fungal populations in the soil which in turn resulted in increased kernel colonization and subsequent aflatoxin contamination. A combination of SLA and RLD, and kernel colonization had a significant influence on aflatoxin contamination under drought conditions in both seasons (r = 0.73** and 0.76**). The results revealed that drought tolerance traits (SLA and RLD) could be contributing to resistance to aflatoxin contamination suggesting that a combination of SLA, RLD and kernel colonization could be used as selection criteria in selecting parents for aflatoxin resistance.