Agricultural Science 2022 Jamb Examination

Germination requires a viable seed, sufficient moisture, oxygen, and an appropriate temperature range to activate enzymatic processes and growth. Zero temperature halts metabolic activity and prevents enzyme functions necessary for germination. Therefore, zero temperature is not a favourable condition for germination.

Drilling involves opening narrow furrows or holes in the soil using a stick, knife, or mechanical tool, placing the seeds at the right depth, and covering them with soil. This method ensures even spacing and better seed-soil contact for uniform germination. Broadcasting and dibbling differ in that they lack the precision of drilling.

When a viable seed is exposed to moisture, air, and proper temperature, the dormant embryo becomes active again and begins to grow. This process is termed germination. It involves the absorption of water, activation of enzymes, and development of the radicle and plumule.

Emergence refers to the point at which the young shoot breaks through the soil surface and becomes visible after germination. It marks the transition from a germinating seed to a seedling. The other terms are incorrect spellings or unrelated to plant development.

Seedlings are the young plants that develop from seeds after germination. They consist of the emerging shoot and root that will later form the mature plant. The other options do not describe this developmental stage accurately.

Key factors in planting operations include spacing, timing, and depth, which determine the health and yield of the crop. ‘Planting weed’ is not a valid consideration, as weeds are unwanted plants that compete with crops for nutrients and light.

Planting depth refers to how far below the soil surface a seed is placed. Correct depth ensures good germination by maintaining adequate moisture and temperature. Planting too deep may prevent emergence, while too shallow planting can expose seeds to desiccation or birds.

A nursery is a controlled environment where seeds are sown and cared for until they develop into seedlings strong enough to be transplanted into the field. It allows for close monitoring of growth conditions, reducing seedling loss and ensuring uniform establishment.

Post-planting operations include activities like thinning, supplying (replacing dead plants), and mulching to support proper crop growth. Ridging, however, is a land preparation method done before or at planting, not after planting, hence it is excluded from post-planting operations.

Thinning involves removing excess seedlings from a seedbed or field to give the remaining plants enough space, nutrients, and light to grow well. It ensures uniformity and prevents overcrowding, unlike supplying, which adds new seedlings where some failed to germinate.