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Physiological disorders

Spongy tissue in Alphonso mango

The cause of spongy tissue formation in Alphonso mango was identified for the first time in the world.  Physiological and biochemical studies have firmly established that the disorder is caused due to the premature onset of germination-associated events in the seed during fruit maturation on the tree/ post-harvest ripening stages.

Based on crucial experimental evidence, 70% fruit maturation stage was identified as the critical phase of fruit growth at which the transition to germination occurs in Alphonso mango. Results have conclusively shown that a reduced content of seed fats during fruit growth led to a reduced concentration of Very Long Chain Fatty Acids (VLCFAs) like, tetracosanoic acid (C 24) and hexacosanoic acid (C 26). These, in  turn, triggered an increased production of cytokinins in seed eventually leading to premature germination while seeds with the normal fat content produced higher level of VLCFAs and hence germination occurred after full maturity of fruit.  The above finding is of paramount importance for effective prevention of ST disorder since treatment of developing fruits on the tree should be completed before the onset of seed germination events.....More

Healthy
 
Spongy
 
 

Jelly seed, a physiological disorder in Amrapali

Seed hormones estimated by HPLC showed that the concentrations of GA and IAA were higher 3 in jelly seed (JS) affected Amrapali mango compared to healthy seed while ABA was higher in healthy seed. The activities of starch phosphorylase, amylase and acid phosphatase enzymes were significantly higher in jelly seed compared to healthy seed. Acid phosphatase is involved in the generation of inorganic phosphate needed for the action of starch phosphorylase which converts stored starch into simple sugars. Concurrently, the contents of total and reducing sugars in seed of jelly seed affected fruits showed an increase (70.3 and 24.1 units ) compared to HS (62.7 and 20.5 units), while starch content decreased from 377.5 units in HS to 297.2 units in JS, supporting the increased rate of degradation of starch in JS seed. The activities of pectinolytic enzymes like, PG and PME were found to be higher in JS fruit pulp compared to H pulp showing that the rate of degradation of pectin was higher in JS fruit compared to H fruit which explained the jelly texture of the JS affected fruit. The calcium content of the jelly seed was higher at 379.6 mg/g compared to 238.1 mg/g in healthy seed indicating the possible migration of the element from pulp to seed during JS development. It was clearly evident from the results that germination associated events had begun in the seed of JS affected fruit.

 

Vivipary

The data obtained with respect to the close link existing between reduced seed fat content, lowered levels of VLCFAs and stimulation of cytokinin biosynthesis leading to premature germination in Alphonso mango, offers a satisfactory explanation for the occurrence of vivipary in mango, a characteristic phenomenon wherein mango seed shows germination during fruit ripening and storage.


Isolation of antioxidants from mango kernel

A method for the isolation of kernel antioxidants from defatted mango kernels was standardized. The yield of antioxidants on dry weight basis was 10 to 12.5 %. DPPH and FRAP activities of the isolated antioxidants were 30 and 10 % more than the ascorbic acid respectively. Total flavonoids were 44.03 mg / g. Extracts were found to be stable when heated up to 200 C for 30 min and when boiled for 30 min in aqueous medium. The extracts were also stable at pH 4 and pH 9. Measurement of acidulant capacity of the extract showed that 0.1 % addition of the extract to water decreased the pH to 4. Addition of 0.15% kernel antioxidants to biscuits prevented lipid peroxidation by 62 % over control when tested after three months of storage. The kernel antioxidants also exhibited antibacterial activity against Bacillus cereus and Enterobacter strains which are common food borne pathogens.

Morpho-physiological interventions to overcome staggered flowering in Alphonso mango

Variable responses of tree shoots to similar environmental stimuli appears to be one of the major causes of staggered flowering behaviour in older Alphonso mango trees. Observations on leaf net P revealed that more than 70% of the N older leaves (> 6 to 8 months) on the tree were photosynthetically less efficient (-7.7 to 1.5 moles m-2 s-1) compared to younger leaves (3 to 11.5 moles m-2 s-1) irrespective of the month in a year. Complete defoliation of trees resulted in highly synchronized vegetative shoot formation with the primordia getting activated within 5 to 7 days irrespective of the month in a year. On the contrary, selective pruning of tertiary branches not only resulted in the loss of active primordia but also altered the canopy architecture. In defoliated trees, the newly formed leaves were photosynthetically active 35-45 days after emergence and contributed consistently to the buildup of carbohydrate reserves leading to vegetative shoot formation and synchronized flowering. Flowering occurred 30-50 days earlier compared to the undefoilated trees. Flowering was not observed in those trees which had flowered and yielded in the previous year due to their alternate bearing nature. Trees that were defoliated in 2012 flowered in the current year, but the fruit number and yield were reduced by 30 to 50% depending on the physiological status of the tree. Yield data revealed that the average fruit weight was 250g in the defoliated trees compared to 180g in the undefoilated trees.