BGCSE Horticulture 1257 cheat sheet

Photosynthesis equation: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2, catalysed by chlorophyll in chloroplasts.

Transpiration pull moves water up xylem; stomata open when guard cells are turgid and close under water stress.

Sexual propagation (seed) gives genetic variation; asexual propagation (cuttings, grafting, division, layering) gives clones identical to the parent.

Cutting success requires a node, adequate humidity, suitable temperature (roughly 18–25 °C for many species) and a rooting medium with good aeration.

Grafting joins a scion to a rootstock; the cambium layers must be aligned so the graft union can form vascular connections.

Monocots have one cotyledon, parallel leaf veins and fibrous roots; dicots have two cotyledons, net veins and a taproot.

Seed germination requires water imbibition, suitable temperature and, for many species, oxygen and light or darkness depending on the species.

Apical dominance: auxin from the terminal bud suppresses lateral buds; pruning the tip releases them and promotes branching.

Soil texture triangle classifies soil by percentages of sand (2.0–0.05 mm), silt (0.05–0.002 mm) and clay (<0.002 mm).

Loam is roughly 40% sand, 40% silt and 20% clay and is generally the most workable horticultural texture.

Soil pH affects nutrient availability; most nutrients are most available between pH 6.0 and 7.0 for many crops.

Cation exchange capacity (CEC) rises with clay and organic matter content; sandy soils have low CEC and leach nutrients readily.

Soil structure is the arrangement of particles into aggregates; organic matter and calcium improve aggregation and porosity.

Field capacity is water held after free drainage; permanent wilting point is where plants can no longer extract water; available water lies between them.

Waterlogging fills soil pores and causes root oxygen starvation; anaerobic soils favour denitrification and root rots.

Soil profile horizons: O (organic litter), A (topsoil), B (subsoil accumulation), C (weathered parent material), R (bedrock).

Essential macronutrients: N, P, K, Ca, Mg, S; micronutrients: Fe, Mn, Zn, Cu, B, Mo, Cl, Ni.

Nitrogen deficiency shows as general yellowing (chlorosis) of older leaves first because N is mobile in the plant.

Phosphorus deficiency often causes stunted growth and purplish discolouration of older leaves.

Potassium deficiency typically shows marginal leaf scorch or browning on older leaves.

Iron deficiency causes interveinal chlorosis on young leaves because Fe is immobile; it is common on high-pH soils.

Manure and compost add nutrients and organic matter; they should be well rotted to reduce pathogens and weed seeds.

Green manures (legumes fix N via Rhizobium) are incorporated to add organic matter and nutrients.

Fertiliser analysis N-P-K (e.g. 10-10-10) gives percentage by weight of N, P2O5 and K2O.

Integrated Pest Management (IPM) order: prevention and cultural control, physical/mechanical, biological, then chemical as last resort.

Aphids are soft-bodied sap suckers; control includes ladybirds, lacewings, soap sprays and removing infested shoots.

Fungal diseases spread by spores under high humidity; improving airflow and avoiding leaf wetness reduce infection.

Bacterial diseases often cause water-soaked lesions and wilting; they spread by splashing water and contaminated tools.

Viral diseases are spread by vectors such as aphids and whitefly and by contaminated tools; there is no chemical cure.

Weeds compete for light, water and nutrients; annual weeds are controlled before seed set, perennials need removal of roots/rhizomes.

Sanitation-clean tools, remove infected debris, quarantine new plants-reduces disease carry-over.

Pesticide labels give dose, interval and harvest interval; resistance develops with repeated use of one chemical group.

Landscape design principles: unity, balance, rhythm, emphasis, proportion and scale.

Plant selection criteria include climate hardiness zone, mature size, light, soil pH and water needs.

Bedding plants are raised in modules or trays and hardened off before planting out to reduce transplant shock.

Pruning types: thinning removes whole branches; heading shortens shoots; both influence flowering on shrubs that flower on old or new wood.

Hedges are trimmed to a slightly battered (narrower at top) profile so light reaches lower foliage.

Lawns: mowing height, frequency, irrigation and fertiliser timing determine density; mow no more than one-third of leaf height at a time.

Transplanting success depends on root ball integrity, planting depth at the original soil line and thorough watering after planting.

Ground cover and mulching reduce weed growth, conserve moisture and moderate soil temperature.

Crop rotation separates plant families (e.g. brassicas, legumes, roots, alliums) to reduce soil-borne disease and pest build-up.

Legumes in rotation fix nitrogen; heavy feeders such as brassicas follow them.

Vegetable sowing depth is about two to three times the seed diameter; spacing follows the mature spread of the crop.

Fruit tree pruning distinguishes spur-bearing and tip-bearing types; remove dead, diseased and crossing wood first.

Thinning fruit improves size and quality and reduces alternate bearing in some species.

Harvest maturity indices include colour, firmness, soluble solids (Brix), size and days from flowering.

Pollination: many fruit crops need compatible cultivars or pollinators; lack of pollinators reduces fruit set.

Irrigation scheduling for vegetables should maintain even moisture; irregular watering causes splitting and blossom-end rot (calcium-related).

Secateurs cut stems up to about 1 cm; loppers handle branches up to roughly 4 cm; pruning saws cut larger wood.

Bypass pruners make clean cuts on living wood; anvil pruners crush and suit dead wood.

Spade for digging and edging; fork for loosening soil; hoe for weeding; rake for levelling and leaves.

Sharpen blades and oil pivot points; disinfect blades between plants to avoid spreading disease.

Greenhouse vs polytunnel: glass gives better light transmission and insulation; polythene is cheaper.

Irrigation systems: drip delivers water to roots with little waste; overhead sprinklers wet foliage and favour disease.

Cold frames and cloches protect seedlings from frost; ventilation prevents overheating and damping-off.

Store tools clean and dry, with blades protected, to prevent rust and injury.

Greenhouse temperature control uses vents, fans and shading; overheating and poor airflow cause leggy growth and disease.

Damping-off in seedlings is caused by soil fungi under wet, crowded, poorly ventilated conditions; sow thinly and ventilate.

Hardening off gradually acclimatises plants raised under protection to outdoor conditions over about 7–14 days.

Rooting media for cuttings need good aeration and drainage; perlite and coarse sand improve drainage.

Sterile seed-raising mix reduces pathogen load; reuse of mix increases disease risk.

Potting-on should occur before roots become pot-bound; choose the next pot size stepwise.

Photoperiod and supplementary lighting control flowering in some crops; shade netting controls light intensity and temperature.

Hygiene in the nursery: clean benches, clean containers, clean water and removal of diseased stock.

Cooling after harvest slows respiration and ethylene production, extending shelf life.

Ethylene is a ripening gas; keep ethylene-producing produce (e.g. ripe fruit) away from sensitive crops to avoid spoilage.

Chilling injury occurs in tropical produce stored too cold; each crop has a recommended storage temperature.

Grading and sizing improve market value and consistency; damaged produce should be culled before storage.

Gross margin = gross output (yield × price) minus variable costs; fixed costs are not included in gross margin.

Break-even output = fixed costs ÷ (price per unit − variable cost per unit).

Market research identifies demand, price and competition before production is planned.

Record keeping (inputs, yields, sales) supports planning, costing and evidence for loans or grants.

Crop rotation, cover crops and composting reduce reliance on synthetic inputs and improve soil health.

Integrated pest management reduces pesticide use, protecting beneficial insects and reducing resistance.

Water conservation: mulching, drip irrigation and rainwater harvesting reduce waste and runoff.

Pesticide safety: read the label, wear PPE, observe re-entry and harvest intervals, and dispose of containers safely.

Risk assessment identifies hazards (tools, chemicals, machinery, manual handling) and controls them before work begins.

Composting requires a balance of carbon-rich 'browns' and nitrogen-rich 'greens', moisture and aeration.

Avoid burning or dumping waste; separate green waste for composting or recycling.

Protect pollinators by avoiding sprays during flowering and choosing products least harmful to bees.

A fair test changes one variable while keeping others constant, with a control and repeated measurements.

Record quantitative data (height, number of leaves, mass) with units and dates; use tables and graphs to present results.

Random sampling and adequate sample size reduce bias; measure the same way each time using the same tool.

Calculate means, and use simple comparisons or graphs to identify trends; state conclusions supported by data.

Propagation records should note date, method, medium, temperature and success rate.

Soil testing (pH, texture by feel, drainage) informs amendment choices before planting.

Safety in practical work: correct lifting, tool handling, PPE and awareness of others nearby.

Evaluate results against the original aim and identify improvements or sources of error for the next trial.

Sustainable practice: maintain soil organic matter, minimise soil disturbance and keep soil covered.

Biodiversity features such as hedgerows, ponds and flowering strips support natural enemies of pests.

Nutrient runoff pollutes watercourses; apply fertiliser at the right rate and time and avoid application before heavy rain.

Renewable and efficient inputs (solar, rainwater, local compost) reduce the carbon footprint of production.

Waste hierarchy: prevent, reuse, recycle, recover, dispose.

Chemical storage must be secure, labelled and away from water sources and children.

Emergency procedures for chemical contact: follow label first aid, wash with water and seek medical help.

Energy and water audits identify where savings can be made in protected and nursery systems.

Measure plant growth using a ruler or tape consistently from the soil line to the growing tip.

Use a soil thermometer and pH meter or test kit; calibrate and record readings with date and location.

When comparing treatments, use the same cultivar, sowing date and growing conditions for all replicates.

Calculate percentage germination = (number germinated ÷ number sown) × 100.

Present data in a labelled table with units, and plot a line or bar graph with labelled axes.

Repeat trials at least three times; report the mean and note variability.

Keep a dated diary of operations (sowing, watering, feeding, pest sightings) to support investigation.

Conclude whether the hypothesis was supported and suggest a realistic improvement to the method.

Sow seeds at the correct depth and firm the medium lightly; label with crop, cultivar and date.

Water seedlings from below or with a fine rose to avoid displacing seed and causing damping-off.

Prick out seedlings when the first true leaves appear and handle by the leaf, not the stem.

Take cuttings from healthy, non-flowering shoots; cut below a node and remove lower leaves.

Prune with sharp tools, making cuts just above a bud or branch collar for clean healing.

Test soil drainage by digging a hole, filling with water and observing how quickly it drains.

Keep a weekly record of watering, feeding and pest checks for each crop or plant group.

Evaluate the finished crop or planting against the original plan and note improvements.