PHYSIOLOGICAL DISORDERS

PHYSIOLOGICAL DISORDERS

PHYSIOLOGICAL DISORDERS
1. Hollow Heart:
  • It is caused by rapid growth of tubers.
  • Tubers become oversized and remain empty with in leading to the formation of cavity in the centre with the death of the small area of pith cells.
  • This results in adjacent cracks and hollowness as the centre expands during the growth of the potato
Management
  • Maintain soil moisture conditions to the optimum level. Avoid over fertilization particularly N.
  • Grow those varieties which are less prone to this defect.
2. Black Heart:
  • It is caused by sub-oxidation conditions under potato tuber storage in piles as the air does not get into the centre.
  • It occurs due to higher temperature and excessive moisture resulted in blackening of tissues in the centre.
  • The appearance of the tuber affect the consumers otherwise there is no decay.
Management
  • Provide proper ventilation. Keep potato tubers in layers. Do not store tubers in the heap.
3. Greening:
  • There are various factors which increases the glycoalkaloid contents such as mechanical injury, premature harvest, and excessive application of fertilizers or exposure of tubers to sunlight which leads to solanin production which is slightly poisonous.
Management
  • Proper earthing up of tubers as the tuberization takes place. Store tubers in darkness after digging up.
4. Knobbiness:
  • It occurs due to uneven growth of tuber cells/tissues.
  • Uneven watering conditions lead to an obstruction in tuber growth.
  • Heavy irrigation after a long dry spell leads to growth of some cells very fast resulting in knobbiness.
Management
  • Frequent and optimum irrigation supply is the remedy
5. Cracking:
  • It is due to boron deficiency or uneven water supply
Management:
  • Application of Borax @ 20kg/ha. Frequent and optimum irrigation supply is the remedy
6. Sun Scalding:
  • It occurs, generally, in the autumn crop when the temperature is high and sunshine is more.
  • Emergence of sprout and leaflets is drastically effected at that time i.e. tip burn. It appears when temperature is more than 30oC.
Management
  • Water should be passed through the furrows to lower the soil temperature.
7. Translucent End:
  • It is related to environmental stress and occurs due to draught and heat.
  • It is, generally, found at the proximal end of the tuber.
  • Tubers show glossy appearance and are irregular in shape.
  • This also results in decay in storage. These glossy areas are high in sugar and low in total soluble solids
Management:
  • Avoid excessive nitrogen supply. Maintain 50% moisture in the field.
8. Black Spot:
  • It means the internal browning of potato tubers.
  • It occurs in vascular tissues with in 3 days of mechanical injury.
  • Phenoles are related to black spot in potato tubers.
Management
  • Genetic make up of the varieties. Provide proper storage and growing conditions.
9. Freezing Injury:
  • It occurs due to the exposure of tubers to freezing temperature during or after harvest.
  • It takes place at -1.5oC or below temperature.
  • There is discolouration of the tissues and affect the vascular tissues at ring called ring necrosis.
  • When fine elements or cells of vascular ring are affected, then it is called as net necrosis.
  • This leads to unmarketable tubers. Tubers show more damage towards proximal end.
Management
  • Avoid exposure of tubers to freezing temperature during storage or harvest.
10. Sprouting:
  • It is often a serious problem in storage
Management
  • It can be inhibited by spraying maleic hydrazide @ 1000-6000ppm about 2-3 weeks before harvesting.
  • Chemicals like Chloro IPC (N-tetra chloro isopropyl carbonate)@ 0.5% and/or nomyl/amyl alcohol @0.05-0.12mg/ha also help in inhibiting sprouting
11. Swollen Lenticels:
  • This disorder is caused by exposure of the tuber to very wet conditions in the field or in storage due to oxygen deprivation.
  • Besides giving an unmarketable appearance to the tuber, the major problem is that an entrance to pathogenic organisms, bacterial soft rot, pink rot and leak, is created.
Management
  • Avoid over-watering. Avoid harvesting low, swampy spots in the field. Pick fields with good drainage.
  • Avoid condensation in storage. Keep storage well ventilated.
Last modified: Sunday, 17 June 2012, 6:39 AM