Search

An effective and rapid in vitro regeneration protocol of Kalmegh (Andrographis paniculata) was established by investigating the factors like combinations of plant growth regulators and explant types (stem, leaf and midrib). To find out the effective medium for callus induction and shoot regeneration, different explants of A. paniculata were cultured on MS media enriched with several concentrations of 6-benzylaminopurine (BA), α-naphthalene acetic acid (NAA) and 2, 4-dichlorophenoxy acetic acid (2,4-D). Stem explant was noticed more responsive than leaf and midrib explant both in callus initiation and shoot regeneration. The ranges of callus initiation from stem, leaf and midrib explants were 26.67 - 100%, 20 - 93.33% and 13.33 - 73.33%, respectively. The calli obtained from midrib explants were not used in shoot initiation because of its poor size. The stem explant exhibited the maximum 73.33% shoot regeneration frequency in a comparison with leaf explants (60%). The maximum callus induction (100%) and shoot regeneration (73.33%) from stem explants were noticed in MS medium strengthened with 0.5 mg/L NAA and 2.0 mg/L BA and half strength MS media complemented with 0.1 mg/L NAA and 3.0 mg/L BA respectively. The highest shoot regeneration from the stem explant may be due to presence of more active parenchymatous cells than that of leaf explant. Half MS medium fortified with 2.0 mg/L IBA considered as best root initiation medium as it resulted in maximum rooting (93.33%). After acclimatization, the plants were transferred to field and found identical to the mother plant.

An experiment was conducted to estimate the genetic variability of 15 indigenous and exotic squash genotypes assessing 18 quantitative and 8 qualitative traits. Results showed that the accessions have high variability in qualitative traits like fruit size, fruit shape, fruit skin colour,lustre and fruit productivity, which allowed selection for considerable gains in these characteristics. The quantitative traits such as fruits yield per plant, fruit weight, length, diameter and total yield per hectare showed the greater phenotypic coefficient of variation (PCV) along with higher heritability which can helps to identify desirable genotypes. The obtained significant and positive correlation between fruit yield with number of leaves, nodes, fruit length, weight and number could assist in selection to improve this crop. Cluster analysis resulted in the formation of 4 groups, confirming the genetic variability among the studied genotypes. Eventually, the attained PCA analysis result revealed that the number of fruits per plant, fruit yield per plant, fruit length and days to first female flowering are the most discriminating traits which are accelerating the variability in squash genotypes. On the basis of the yield and its attributing traits, First Runner is the best genotype suited in this environment.