Assertion: The depth of sowing has an important effect on some pathogens, notably those which attack seedlings.
Reasoning:: By delaying the emergences of seedlings, deep sowing may help to increase the resistance of a susceptible crop to a pathogen.
Reasoning:: By delaying the emergences of seedlings, deep sowing may help to increase the resistance of a susceptible crop to a pathogen.
Answer & explanation
Correct answer: option 1
Sowing practices, such as changing time, depth and direction of sowing, and changing the density of the crop can protect plants from pathogens to which they are susceptible only at certain stages of their development. Changing the time of sowing can exploit weather conditions that are unfavourable to the pathogen, thus reducing crop losses. This might require the use of a specific cultivar that is adapted to the selected growing period, but might also be susceptible to different pathogens. The depth of sowing can have a bearing on the chance of infection, as the seedling"s pre-emergence stage, which is usually more susceptible to attack, is longer when seeds are planted deeper. However, deeper planting can stimulate germination.