ibps-so 2016 · Question 360 of 394

A cold storage nanced by the branch has been served with a claim by a potato trader whose consignment has been rejected by the processing company. The tubers are sound on the outside and free of any rot or smell, but on cutting them the central tissue is found to be blackened in an irregular patch, and the a ected tubers had been stacked in the middle of a tightly packed heap in a chamber in which the fan had failed for two days at a high storage temperature. The eld o cer investigating the claim nds no fungus and no bacterium on plating the a ected tissue, and notes that the trouble is con ned to the interior of the heap where the respiring tubers had used up the air around them and where the heat of respiration had built up, the surface layers of the same heap being entirely sound. Black heart of potato is caused by

1. AA bacterium, Erwinia carotovora
2. BDe ciency of boron in the soil in which the crop was raised
3. CDe ciency of oxygen in the tuber during storageCorrect
4. DA soil-borne virus carried over from the seed tuber
5. EAn excess of nitrogen applied to the standing crop