The Effects of Naphthaleneacetic Acid on the Rooting of Cycas revoluta Bulbs

The effects of naphthaleneacetic acid (NAA) (0, 15, 20 and 25 mg/l) were explored on the rooting of Cycas revoluta bulbs in a study based on a randomized complete block design with four replications. Based on the results, the NAA treatments significantly influenced root length, leaf fresh and dry weight, and chlorophyll. But, they did not affect root number, root fresh and dry weight, significantly. The longest roots were 9.43 and 9.63 cm produced by the bulbs treated with 25 and 20 mg/l NAA, respectively. The 25 and 20 mg/l  NAA were related to the highest root number of 3.57 and 3.23, respectively, the 25 mg/l  NAA was related to the highest mean root fresh weight of 4.9 g, the 25 mg/l  NAA was related to the highest root dry weight of 2.5 g, the 20 and 25 mg/l NAA were related to the highest leaf fresh weight of 6.04 and 6.54 g, respectively, the 25 and 20 mg/l NAA were related to the highest leaf dry weight of 4.07 and 3.11 g, respectively, and the 20 and 5 mg/l NAA were related to­­ the highest chlorophyll content of 6.28 and 6.22 mg g-1 F.W., respectively. A significant relationship was observed between leaf dry weight and chlorophyll content at the P 0.01 level (+0.78). But, there was no significant relationship between root dry weight and mean root length (+0.29). The relationship between chlorophyll content and mean root length was not significant either (+0.13). According to the results, increasing the hormone rate may even affect the plants adversely, injuring them. In general, it can be inferred from the results that NAA at the rate of 20 mg/l influenced the studied traits, thereby entailing the highest gene expression in C. revoluta.