Assessment of variability in annona spp.

Abstract

Annona spp. is a group of underutilized fruit crops with tremendous potential. Among these, Annona reticulata, A. squamosa, and A. muricata are seen as a homestead crop in Kerala. Since Annona spp. is cross pollinated as well as a seed propagated fruit crop, there exists wide variability indicating scope for selection of promising types. In a purposive sample survey, 71 trees comprising of 30 trees of Annona reticulata, 16 trees of A. squamosa and 25 trees of A. muricata were identified from the homesteads of Ernakulam, Thrissur and Palakkad districts of Kerala. The accessions were notated as AR for A. reticulata, AS for A. squamosa and AM for A. muricata. They were further evaluated for their morphological, biochemical characters as well as for sensory evaluation. Tree characters, leaf characters, inflorescence characters, fruit characters and quality parameters were recorded as per IPGRI crop descriptor. Morphological characters such as tree, leaf, floral and fruit characters were distinct for the three species. Flowering and fruiting seasons exhibited wide variability among the three species irrespective of districts. In A. reticulata and A. muricata, flowering was from August to March and fruiting was from September to May. In A. squamosa, flowering was observed from January to June and fruiting was from February to August. Wide variability was observed in fruit characters and quality parameters of A. reticulata accessions. The fruit weight ranged from 110 g (AR 14) to 435 g (AR 9).TSS, titratable acidity, total sugar and antioxidant activity of the fruits ranged from 13.4 0Brix (AR 8) to 16.6 0Brix (AR 6), 0.16 to 0.29 per cent, 9.7 (AR 13) to 11.36 per cent (AR 26) and 1.26 mg (AR 7) to 2.86 mg (AR 6) of ascorbic acid per g of sample respectively.In A. squamosa, individual fruit weight varied from 81.5 g (AS 6) to 116.9 g (AS 16). The TSS, titratable acidity, total sugar and antioxidant activity of the fruits ranged from 18.23 0Brix (AS 3) to 19.9 0Brix (AS 7), 0.16 to 0.22 per cent, 11.26 (AS 3) to 12.78 per cent (AS 7) and 1.64 mg (AS 14) to 2.86 mg (AS 2 and AS 7) of ascorbic acid per g of the sample respectively. Fruit weight in A. muricata ranged from 410 g (AM 2) to 850 g (AM 18).TSS of the fruit samples varied from 12.2 0Brix (AM 16) to 14.9 0Brix (AM 19). The titratable acidity, total sugar and antioxidant activity ranged from 0.36 to 0.38 per cent, 7.72 (AM 23) to 9.57 per cent (AM 19) and 3.52 mg (AM 2) to 4.52 mg (AM 25) of ascorbic acid per g of sample respectively. The principal component analysis of accessions based on all quantitative observations separately for the three species revealed variability existing between them. The common and distinct characters of the species were fruit weight, number of flakes per fruit and shelf life. The principal component analysis for three species was performed separately to determine promising types based on the characters such as fruit weight, yield of fruits per tree, number of seeds per fruit, TSS, acidity, total sugar and antioxidant activity. The clustering of the three species done separately using score plot confirmed that the promising accession in A. reticulata is AR 2, in A. squamosa are AS 7 and AS 11 and in A. muricata is AM 8. In sensory evaluation, the accessions AR 21 and AR 3 of A. reticulata, AS 8 and AS 16 of A. squamosa and AM 19 and AM 12 of A. muricata were preferred by the panelist. The study revealed that the three different species of Annona had wide variability in terms of their growth, vegetative, flowering and fruit characters. Among the three species, with regard to fruit quality parameters, Annona squamosa wassuperior in TSS and total sugar whereas fruits of Annona muricata were superior with respect to antioxidant activity. Performance of the identified promising types is to be evaluated for another 3-4 years so as to ascertain the performance. There is also a scope for extending the studies to other districts so as to make an account of the total variability available and to select the most promising types in each species suited for Kerala condition.