Agronomy - Study Mode
[#436] Optimum plant population ha -1 for cotton has estimated as
Correct Answer
(C) 50,000 - 80,000
Explanation
Solution: The optimum plant population or density of a crop plantation is the arrangement per unit area that allow crops to exploit resource optimally and produce high yields. The optimum plant population per hectare for cotton has estimated as 50,000 - 80,000. India has about 37% of the world's area under cotton cultivation and is the largest producer of cotton in the world accounting for 22% of total production.
[#437] The most important potential contaminant of food produced on sewage sludge amended soil is
Correct Answer
(D) Cadmium
Explanation
Solution: Cadmium is the natural element found in tiny amounts in air, water, soil and food. Dumping of sewage sludge into the soil leads to soil pollution and various heavy metals like cadmium, lead, etc present in waste water amend in soil and cause contamination of soil also to the foods and crops grown on that soil. This makes soil potentially toxic to the plants.
[#438] The optimum cardinal temperature points for germination of rice seeds are
Correct Answer
(C) 20°C - 25°C
Explanation
Solution: The optimum cardinal temperature for any plant is the temperature range within which the seeds of a particular species can germinate. The optimum cardinal temperature for germination of rice seeds is 20°C - 25°C.
[#439] Grassy stunt virus desease of rice is transmitted by
Correct Answer
(B) Brown plant hopper
Explanation
Solution: A grassy stunt virus disease of rice is transmitted by Brown plant hopper nymphs and adults. It transmits in an area where rice is grown all around the year. The macropterous forms or long-winged adults of the insect are more important in spreading the disease than the short winged forms. They feed on the diseased plant for at least 30 minutes to pick up the virus.
[#440] Concentration of which element is highest in soil
Correct Answer
(A) O 2
Explanation
Solution: The mineral matter of soil is comprised of eight main elements, Oxygen, silicon, Aluminum, Iron, Magnesium, Calcium, Sodium and potassium. Out of these Oxygen is most prevalent on both and volume basis and is the only negatively charged ion, which combines with other cations in different ratios to form different compounds required for the proper growth and development of the plant.