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Fig. 2: Effects of different concentrations of IAA on chlorophyll ‘a’ (A), chlorophyll ‘b’ (B), total chlorophyll

(C), phenolic (D) and flavonoids content (E) of Silybum marianum.

DISCUSSION

Root length increased with the application of IAA. IAA positive effect on root length at
20, 40 and 60 days of spraying. Maximum root length was observed at 100 ppm

concentration at 60 days of spraying. The result of the study revealed that IAA treatment had

a significant effect on root length. Plants have longer roots at all PGRs concentration as

compared to control plants. Zaman et al. (2001); Sanavy and Moeini (2003) and Uddin (2006)
emphasized that escalation in root length is crucial for plant tolerance to adverse
environmental conditions. Primary root elongation is a well-characterized function of both

auxin and gibberellins (Li et al., 2015). Hussain et al. (2011); and Vakharia and Solanki

(2013) studied effects of IAA on Cassia absus, and Withania somnifera respectively, and
recorded increased root length with increasing PGRs concentrations.

IAA had more effect in increasing leaf area of Silybum marianum as compared to control
plants. Results of present study revealed that increased leaf area is an adaptive response of S.

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