861. The living together of two or more species in a prolonged and intimate ecological relationship is called________________?

A. Symbiosis
B. Biosystem
C. Auto environment
D. Climate

862. Pulling of off- type plants from a cropped field is called___________________?

A. Rouging
B. Weeding
C. Pruning
D. None of the above

863. The ratio of actual cultivated area to a total farm area over a year is called__________________?

A. Cropping pattern
B. Cropping intensity
C. Cost-benefit ratio
D. None of the above

864. The wearing away of the land surface by wind, water, ice or other geological agent is called__________________?

A. Seepage
B. Soil conservation
C. Erosion
D. fertility depletion

865. The harmful influence of one living plant on another living plant by the secretion of a toxic substance is called________________?

A. Allergy
B. Allelopathy
C. Parasitism
D. Antagorusm

866. The heating of atmosphere by gases that are transparent to sun light but opaque to radiated heat is called________________?

A. Green house effect
B. Pollution
C. Warming
D. Solar radiation

867. The total dry matter produced by a plant as a result of photosynthesis is called_________________?

A. Biological yield
B. Harvest index
C. Dry matter
D. Crop growth

868. The application of fertilizer nutrients in proportions best suited to the needs of the crop is called_________________?

A. fertilizer placement
B. fertilizer use efficiency
C. Nitrogen use efficiency
D. Balanced fertilization

869. Soil water in excess of hygroscopic and capillary water which moves downward through the soil by the force of gravity is called______________?

A. Capillary water
B. sub-surface water
C. Gravitational water
D. Run off water

870. Weedicides that kill the foliage of weeds by direct contact are as________________?

A. Trifluration
B. Paraquet
C. Bromoxy nil
D. Loxynil