AP BIOLOGY

Detailed explanation-1: -The general thumb rule is that the seed should be sown twice as deep as seeds length. 4. Sow the seed thinly, as crowded thick sowing is wasteful, it later requires extra efforts in removing unwanted seedlings & it may also encourage the ‘damping off’ disease.

Detailed explanation-2: -The seeds should be sown at appropriate depth because seeds sown superficially can be eaten by the birds. But they should not be sown too deep also. In addition to this, the seeds should not be sown too close as the plants will not get sufficient space to grow and will compete for space, nutrients, and sunlight.

Detailed explanation-3: -Seed size had little effect on seedling emergence time, but plants derived from large seeds were larger than those from small seeds. Increased sowing depth delayed seedling emergence and reduced seedling relative growth rate (RGR).

Detailed explanation-4: -If the seed is sown too deep, the seedling has to fight through more earth before feeling the sunlight on its leaves. It may run out of steam before breaking the surface, or once it does emerge it may be weakened, and a poor early start to growth is difficult to recover from.

Detailed explanation-5: -Planting too shallow may result in poor germination due to low soil moisture retention near the soil surface or seed injury due to insects or disease. Similarly, if placement is too deep, seed may have delayed germination due to lower soil temperatures or result in poor germination or seed injury.