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An organism used as a biofertilizer for raising soyabean crop is
(b) Rhizobium leguminosarum is a symbiotic bacteria found in root nodules of legume. This bacterium has nitrogen fixing gene and fixing N2. Soyabean is a legume. Thus, Rhizobium is used as a biofertilizer for raising soyabean crop.
An element playing important role in nitrogen fixation is
(a) Molybdenum is absorbed as molybdate by plants. It is involved in nitrogen metabolism including nitrogen fixation. It is a component of enzyme nitrogenase and acts as enzyme activator. Its deficiency causes chlorosis and necrosis, whiptail of cauliflower and premature leaf fall.
Copper is absorbed by the plant in ionic form. Its deficiency causes necrosis, dieback in Citrus, reclamation in legumes.
Manganese is absorbed by the plants as bivalent ion. It acts as enzyme activator. Its deficiency causes interveinal chlorosis as well as yellowing of starch and their subsequent degenerate.
Zinc is needed for biosynthesis of IAA and also acts as enzyme activator. Its deficiency causes chlorosis, little leaf, rosette, white bud of maize and mottling of leaves
Which one of the following is not a micronutrient?
(b) The essential elements, which are required by plants in comparatively large amounts are called as macro elements, eg, C, H, O, N, P, K, Ca, S, Mg, Fe. The elements, which are required in very small amount by the plants are called micro elements, eg, Zn, Mn, B, Cu, Mo and Cl.
Farmers in a particular region were concerned that pre-mature yellowing of leaves of a pulse crop might cause decrease in the yield. Which treatment could be most beneficial to obtain maximum seed yield?
(d) If a pulse crop possesses premature yellowing of leaves and decrease in yield and application of magnesium and iron to promote synthesis of chlorophyll may become most beneficial to overcome the problem and to obtain maximum seed yield.
Magnesium is an important part of ring structure of chlorophyll molecule and its deficiency causes chlorosis and premature leaf abscission.
In iron deficiency also, the leaves become chlorotic because iron is required for the synthesis of some of the chlorophyll protein complexes in the chloroplast.
Sulphur is an important nutrient for optimum growth and productivity in:
(a) Sulphur is constituent of certain amino acids. The amino acids form the protein by polymerisation. The pulses are rich in protein.
Hydroponics is
(d) : Hydroponics is soilless cultivation of plants by placing the roots in the nutrient solution.
Leghaemoglobin is produced in response to
(d) : Bacteria like Rhizobium and Frankia live free as aerobes in the soil but are unable to fix nitrogen. They develop the ability to fix nitrogen only as a symbiont when they become anaerobic. They are unable to fix nitrogen by themselves. Roots of a legume secrete chemical attractants. Bacteria collect over the root hairs and form an infection thread enclosing the bacteria. Infection thread grows alongwith multiplication of bacteria. Bacteria stop dividing and form irregular polyhedral structures called bacteroids. In an infected cell bacteriods occur in groups surrounded by host membrane. The host cell develops a pinkish pigment called leghaemoglobin (Lb). It is oxygen scavenger and is related to blood pigment haemoglobin. It protects nitrogen fixing enzyme nitrogenase from oxygen.
Plants do not get benefit from
(d): Ozone is a harmful secondary air pollutant. Ozone, being a strong oxidant destroys chlorenchyma, produces necrosis, hardens rubber, damages textiles, corrodes the surface of marble statues and heritage buildings.
Hydroponics cannot be used in the commercial production of vegetables such as
Page number-195
12.1 Methods To Study The Mineral Requirements of Plants
Mineral Nutrition
Which of the following is the essential requirement of Hydroponics?
Page number-195
12.1 Methods To Study The Mineral Requirements of Plants
Mineral Nutrition
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