CENEVAL EGEL Plus Ciencias Agrícolas (EGEL Plus AGRO)

An agronomist is planning a commercial grain maize (Zea mays) planting. The target plant population is 75,000 plants per hectare at harvest. The certified seed lot has a germination rate of 95%, a physical purity of 98%, and historical local field emergence is 90%. If the 1,000-seed weight is 320 grams, what is the required seeding rate in kilograms of seed per hectare (rounded to one decimal place)?

• A24.0 kg/ha
• B28.6 kg/ha
• C33.5 kg/ha
• D38.2 kg/ha

In cattle and other ruminants, what is the main source of metabolizable energy obtained from fibrous forages fermented in the rumen?

• AGlucose absorbed directly from the rumen after cellulose is fully hydrolysed
• BVolatile fatty acids (mainly acetate, propionate and butyrate) produced by rumen microbes…
• CFree amino acids released from forage protein and absorbed in the reticulum
• DLactic acid produced by the animal's own salivary enzymes

A soil test and crop demand curve recommend a total fertilization of 180 kg N/ha for irrigated bread wheat. At planting, the producer applied 150 kg/ha of diammonium phosphate (DAP, 18-46-0) into the seedbed. How much urea (46-0-0) in kg/ha must be applied at tillering as topdressing to satisfy the remaining nitrogen requirement?

• A153 kg/ha
• B267 kg/ha
• C333 kg/ha
• D391 kg/ha

A tomato grower observes marginal chlorosis and subsequent necrosis ('leaf scorch') along the margins of the oldest lower leaves, while fruit development shows uneven ripening and yellow shoulder disorder. Which essential nutrient deficiency is responsible for these symptoms?

• ANitrogen (N)
• BPotassium (K)
• CIron (Fe)
• DCalcium (Ca)

An agronomic station tracks thermal accumulation for sweet corn using the standard Growing Degree Day (GDD) formula with a base temperature (Tbase) of 10°C and an upper cut-off temperature of 30°C. On a given day, the maximum temperature recorded was 34°C and the minimum was 14°C. How many GDD (°C-day) accumulated on that day?

• A11.0 GDD
• B12.0 GDD
• C14.0 GDD
• D16.5 GDD

A producer plans artificial insemination in a beef herd and must predict when cows that did not conceive will show heat again. What is the average length of the estrous cycle in cattle?

• AAbout 7 days
• BAbout 21 days
• CAbout 45 days
• DAbout 114 days

Using the Pearson square, a nutritionist mixes ground maize (9% crude protein) with soybean meal (44% crude protein) to obtain a 16% crude protein concentrate. What percentage of the mixture must be soybean meal?

• A16%
• B20%
• C28%
• D80%

In commercial avocado (Persea americana) orchard design in Michoacán, 'Hass' is classified as a Type A floral cultivar. Why must Type B cultivars (such as 'Fuerte' or 'Zutano') be interplanted at a 10% to 15% ratio?

• AType B trees serve as sacrificial trap crops for the avocado seed weevil (Conotrachelus a…
• BType A flowers are functionally female in the morning and male in the afternoon of the ne…
• CType B rootstocks secrete allelopathic flavonoids that suppress Phytophthora cinnamomi ro…
• DType A cultivars are triploid and completely pollen-sterile, requiring diploid Type B pol…

An agronomist establishes an open-field bell pepper (Capsicum annuum) crop with raised beds spaced 1.20 meters center-to-center. Each bed has a single drip line and a single row of plants spaced 0.25 meters apart along the row. What is the calculated plant density per hectare?

• A25,000 plants/ha
• B33,333 plants/ha
• C40,000 plants/ha
• D50,000 plants/ha

A broiler flock consumed 18,900 kg of feed and produced 10,500 kg of live weight gain. What is the feed conversion ratio (FCR)?

• A0.56
• B1.80
• C2.80
• D8.40

A pig farm schedules farrowing crates for sows served on 1 March. Approximately how long is the gestation period of the sow?

• AAbout 60 days
• BAbout 114 days (three months, three weeks and three days)
• CAbout 150 days
• DAbout 283 days

What process preserves chopped whole-plant maize stored as silage in a well-sealed silo?

• AAerobic composting, which heats the forage enough to sterilize it
• BAnaerobic fermentation by lactic acid bacteria, which lowers the pH to about 4 and inhibi…
• CComplete drying of the forage to below 12% moisture before sealing
• DAddition of ammonia to raise the pH above 9 and kill all microorganisms

A fertilizer recommendation requires 92 kg of P2O5 per hectare for dry bean establishment. If Triple Superphosphate (TSP, 0-46-0) is chosen as the exclusive phosphorus source, how much commercial TSP must be applied per hectare?

• A140 kg/ha
• B184 kg/ha
• C200 kg/ha
• D246 kg/ha

Which diagnostic indicator reliably confirms that a field of grain maize has reached physiological maturity (R6 stage)?

• ASilks turning brown and dry at the ear tip
• BKernel milk line progressing to 50% of the kernel face
• CFormation of a dense black layer (black abscission layer) at the kernel tip base and maxi…
• DMoisture content of grain dropping below 14% while standing in the field

In a HACCP (Hazard Analysis and Critical Control Points) plan for a fresh-produce packing house, what is a critical control point (CCP)?

• AAny step in the process where a quality defect such as bruising can occur
• BA step at which control can be applied and is essential to prevent, eliminate or reduce a…
• CThe final inspection point where a government official certifies the shipment
• DThe document that lists the cleaning schedule for the packing line

The label of an insecticide registered for tomato states a pre-harvest interval (intervalo de seguridad) of 7 days. What does this requirement mean?

• AWorkers may not re-enter the treated field for 7 days after the application
• BAt least 7 days must pass between the last application and harvest, so that residues decl…
• CThe product must be applied every 7 days to keep the pest under control
• DThe product loses its effectiveness 7 days after the container is opened

In the Bajío and northern agricultural zones of Mexico, why do agronomists select short-day onion (Allium cepa) cultivars for autumn sowing and spring harvest?

• AShort-day onions initiate bulb expansion when day length reaches only 11 to 12 hours, all…
• BShort-day onions only flower when photoperiod exceeds 16 hours of continuous daylight
• CLong-day cultivars bulb prematurely in winter before developing sufficient photosynthetic…
• DShort-day onions require sub-zero chilling hours to synthesize alliinase precursors

A rain-fed maize crop suffered drought and heat stress during grain filling, and ear damage by insects was common. Which food-safety hazard is most likely to have increased in the harvested grain?

• AAflatoxin contamination produced by Aspergillus flavus
• BResidues of copper from foliar fungicides
• CContamination with Salmonella from irrigation water
• DNitrate accumulation in the kernels

The GGAVATT model developed by INIFAP in Mexico is best described as which kind of technology-transfer strategy?

• AA national subsidy program that delivers inputs directly to individual farmers
• BGroups of livestock producers who validate and adopt technologies on their own ranches wi…
• CA certification scheme for exporting beef to international markets
• DA mass-media campaign that broadcasts technical recommendations by radio

In technology transfer, what distinguishes a validation plot (parcela de validación) from a demonstration plot (parcela demostrativa)?

• AA validation plot tests whether a technology developed at a research station performs wel…
• BA validation plot is always located on an experiment station, whereas a demonstration plo…
• CA validation plot evaluates only new varieties, whereas a demonstration plot evaluates on…
• DThere is no difference; both terms describe the same activity

According to Everett Rogers' diffusion of innovations model, which group of producers, about 13.5% of a population, adopts a new technology after the innovators and is often respected as opinion leaders?

• ALaggards
• BEarly majority
• CEarly adopters
• DLate majority

What is the central learning method of Farmer Field Schools (Escuelas de Campo), promoted by FAO for integrated pest management?

• ALectures by specialists at a regional university, followed by a written exam
• BGroups of farmers who meet regularly in a field throughout a crop season to observe, expe…
• CDistribution of printed technical manuals to each farmer's home
• DContracts in which a company supplies inputs and buys the harvest at a fixed price

In alfalfa (Medicago sativa) forage management, what physiological growth stage represents the optimal compromise between crude protein content, digestible forage yield, and persistence of crown root carbohydrate reserves?

• AEarly vegetative stage (stems under 15 cm)
• BEarly bloom stage (10% flowering or appearance of crown basal regrowth buds)
• CFull bloom stage (100% open flowers with initial seed pod formation)
• DComplete post-seed maturity

In agricultural research and extension in Mexico, what is a technological package (paquete tecnológico) for a crop?

• AA single improved variety sold in sealed bags
• BThe integrated set of recommendations for a crop and region, such as variety, planting da…
• CA government credit line for purchasing agricultural machinery
• DThe software used to record field data on a tablet

An on-farm trial compares a new fertilization recommendation with the producer's usual practice on several farms. What is the role of the plot managed with the producer's usual practice?

• AIt serves as the control (testigo) against which the new recommendation's effect on yield…
• BIt is used only to multiply seed for the next season
• CIt is excluded from the analysis because it does not receive the new treatment
• DIt replaces the need for replication across farms

An agricultural engineer calibrates a tractor-mounted boom sprayer prior to applying an herbicide. The tractor travels at a constant forward speed of 6.0 km/h, the nozzle spacing along the boom is 0.50 meters, and the measured average nozzle output is 1.20 liters per minute. What is the calculated application rate in liters per hectare (L/ha)?

• A144 L/ha
• B200 L/ha
• C240 L/ha
• D288 L/ha

In Integrated Pest Management (IPM), what is the key distinction between the Economic Injury Level (EIL) and the Economic Threshold (ET, or Action Threshold)?

• AThe EIL is the pest density at which control actions are taken, while the ET is the point…
• BThe EIL is the lowest pest population density that causes economic damage exceeding contr…
• CThe EIL applies exclusively to fungal plant diseases, whereas the ET applies exclusively…
• DThe EIL represents cosmetic damage thresholds for export markets, whereas the ET represen…

A scouting report in a commercial maize field in Sinaloa indicates that 35% of plants at the V4 stage exhibit 'windowpane' leaf damage with small larvae inside the whorls, confirmed as fall armyworm (Spodoptera frugiperda). Which management strategy achieves maximum control efficiency while preserving beneficial predators?

• ABroad-spectrum aerial fogging of organophosphates at noon
• BApplication of a selective biological or physiological insecticide (such as Bacillus thur…
• CA preventive soil application of a residual pre-emergence herbicide at planting
• DWaiting until the R1 silking stage to treat larvae inside the developed ear tip

Late blight in potato and tomato is caused by Phytophthora infestans. Why are standard ergosterol-biosynthesis-inhibiting fungicides (such as triazoles) ineffective against this plant pathogen?

• APhytophthora infestans is a true fungus that has developed universal resistance to all tr…
• BPhytophthora infestans is an oomycete (Stramenopila) whose cell walls contain glucans and…
• CTriazoles cannot penetrate the waxy cuticle of potato and tomato leaves
• DPhytophthora infestans is a bacterium, so it must be controlled with copper bactericides

Which insect vector is responsible for transmitting the destructive Huanglongbing (HLB or citrus greening) bacterium (Candidatus Liberibacter asiaticus) across Mexican citrus orchards?

• AToxoptera citricida (Brown citrus aphid)
• BDiaphorina citri (Asian citrus psyllid)
• CAleurocanthus woglumi (Citrus blackfly)
• DBrevipalpus yothersi (Citrus flat mite)

What is the primary cellular mechanism of action of the non-selective systemic herbicide glyphosate (HRAC Group 9)?

• AInhibition of the enzyme acetolactate synthase (ALS), preventing branched-chain amino aci…
• BInhibition of the enzyme 5-enolpyruvylshikimate-3-phosphate (EPSPS) synthase in the shiki…
• CDisruption of photosystem II electron transport at the D1 protein quinone-binding site
• DInhibition of protoporphyrinogen oxidase (PPO), generating toxic singlet oxygen

An agronomist prescribes a preventative fungicide application requiring 720 grams of active ingredient (a.i.) of chlorothalonil per hectare. The commercial product on hand is a suspension concentrate containing 720 g/L of chlorothalonil. If the field sprayer is calibrated to deliver 200 L/ha of total spray volume, what volume of commercial product should be added to a 1,000-liter spray tank?

• A2.5 liters
• B5.0 liters
• C7.5 liters
• D10.0 liters

A tomato crop exhibits unilateral leaf wilting, pith necrosis with vascular browning, and characteristic 'bird's-eye' spots on developing green fruit. What seed-borne phytopathogenic bacterium is the causal agent?

• AXanthomonas campestris pv. vesicatoria
• BClavibacter michiganensis subsp. michiganensis
• CPseudomonas syringae pv. tomato
• DRalstonia solanacearum

In augmentative biological control programs for grain and fiber crops, minute wasps of the genus Trichogramma (e.g., Trichogramma pretiosum) are commercially released to target which life stage of insect pests?

• AAdult female moths during mating flight
• BPest eggs, parasiting them before larvae hatch and cause crop feeding damage
• CLate-instar pupae within underground earthen cells
• DEarly-instar nymphs feeding on phloem sap

Which Spanish sentence uses the homophones «hierba» and «hierva» correctly?

• ASe recomienda eliminar la hierva antes de sembrar y esperar a que el agua hierba para est…
• BSe recomienda eliminar la hierba antes de sembrar y esperar a que el agua hierva para est…
• CSe recomienda eliminar la hierba antes de sembrar y esperar a que el agua hierba para est…
• DSe recomienda eliminar la hierva antes de sembrar y esperar a que el agua hierva para est…

According to the Fungicide Resistance Action Committee (FRAC), what is the most effective operational strategy to delay or prevent the evolution of pathogen resistance against single-site systemic fungicides?

• AApplying the same systemic fungicide continuously at half the recommended label rate
• BTank-mixing or rotating the high-risk single-site fungicide with multi-site contact prote…
• CExclusively using post-infection curative sprays after 50% canopy blighting has occurred
• DApplying the fungicide exclusively through overhead sprinkler irrigation without surfacta…

Tomato brown rugose fruit virus (ToBRFV) has become a critical global phytosanitary threat to greenhouse tomato production. Which biological attribute makes ToBRFV exceptionally difficult to manage in protected horticulture?

• AIt is transmitted persistently by whiteflies, so it can be managed mainly with insect-pro…
• BIt is a mechanically stable tobamovirus that overcomes the widely deployed Tm-2^2 resista…
• CIt is transmitted only by aphids in a non-persistent manner, so mineral-oil sprays contro…
• DIt infects only tomato cultivars lacking the Tm-2^2 gene, so resistant hybrids fully prot…

Which Spanish sentence is most appropriate, in precision and register, for the results section of a technical report?

• ALa verdad es que el tratamiento con composta salió mucho mejor y se ve que las plantas cr…
• BEl tratamiento con composta incrementó la altura de planta en 18 % respecto del testigo (…
• CCreemos que la composta es maravillosa porque todas las plantas se veían muy bonitas al f…
• DPues básicamente la composta funcionó, más o menos como esperábamos, en casi todas las pl…

Which Spanish sentence uses the construction with «se» correctly when the direct object is a person introduced by «a»?

• ASe contrató a varios jornaleros para la cosecha.
• BSe contrataron a varios jornaleros para la cosecha.
• CSe contrató varios jornaleros para la cosecha.
• DSe les contrataron a varios jornaleros para la cosecha.

Calculate the Economic Injury Level (EIL) in pests per square meter using the bioeconomic equation EIL = C / (V * I * D * K), given the following parameters: - Cost of management per hectare (C): $80.00 USD/ha - Market value of crop per kilogram (V): $0.40 USD/kg - Yield damage per pest per square meter (D): 2.5 kg loss per pest/m² per ha - Injury coefficient (I): 1.0 - Efficacy of the control measure (K): 0.80 (80% mortality) What is the resulting EIL?

• A50 pests/m²
• B80 pests/m²
• C100 pests/m²
• D125 pests/m²

In Mexican commercial fruit production and export zones (such as mango and citrus), what is the operating principle of the Sterile Insect Technique (SIT) implemented under official phytosanitary campaigns against the Mexican fruit fly (Anastrepha ludens)?

• AReleasing sterilized females whose eggs laid in fruit fail to hatch
• BMass-rearing, radiation-sterilizing, and aerially releasing millions of sterile male flie…
• CTreating commercial fruit with gamma radiation prior to harvesting to kill internal larvae
• DReleasing parasitoid wasps that develop inside fruit fly larvae and kill them

Before mixing a registered agricultural pesticide, which action best applies label-based risk management?

• AUse a familiar dose from memory because products with the same active ingredient always h…
• BReduce protective equipment when the weather is hot, regardless of the label
• CRead the current product label and follow its authorized crop, dose, protective-equipment…
• DCombine the product with any other pesticide unless the label expressly forbids it

In the formulation of an agricultural investment project, which study estimates the demand, supply, prices and marketing channels for the product?

• AThe technical study
• BThe market study
• CThe financial study
• DThe environmental impact study

A loam soil exhibits a gravimetric water content at field capacity (FC) of 28% and at permanent wilting point (PWP) of 14%. The soil bulk density is 1.30 g/cm³, and the effective rooting depth of the crop is 0.60 meters (600 mm). What is the total Available Water Capacity (AWC) in the root zone in millimeters of water depth?

• A84.0 mm
• B109.2 mm
• C135.5 mm
• D168.0 mm

Using the soil with an Available Water Capacity (AWC) of 109.2 mm, an agronomist sets a management allowed depletion factor (p) of 0.50 (50% allowable depletion) to prevent crop water stress. If the average daily crop evapotranspiration (ETc) is 5.46 mm/day, what is the net irrigation depth (RAW) and the required irrigation interval in days?

• ANet depth: 27.3 mm; Interval: 5 days
• BNet depth: 54.6 mm; Interval: 10 days
• CNet depth: 81.9 mm; Interval: 15 days
• DNet depth: 109.2 mm; Interval: 20 days

A weather station calculates a reference evapotranspiration (ET0) of 6.0 mm/day using the FAO-56 Penman-Monteith method. For an established grain sorghum crop at the peak mid-season reproductive stage, the crop coefficient (Kc) is 1.15. What is the daily crop water requirement (ETc)?

• A5.22 mm/day
• B6.00 mm/day
• C6.90 mm/day
• D7.85 mm/day

In an agricultural project budget, which item is classified as working capital (capital de trabajo) rather than fixed investment?

• AConstruction of a greenhouse structure
• BPurchase of a drip irrigation system
• CFunds to buy seed, fertilizer and pay labour until the first harvest is sold
• DPurchase of a tractor

An agricultural well provides irrigation water with an electrical conductivity (ECw) of 1.6 dS/m. The cultivated crop has a threshold soil salinity tolerance of ECe = 4.0 dS/m without yield reduction. Using Rhoades' leaching requirement formula for conventional surface irrigation: LR = ECw / [(5 * ECe) - ECw], what fraction of applied irrigation water must be leached through the root zone to control soil salinity?

• A4.2%
• B8.7%
• C12.5%
• D16.0%