SODICITY TOLERANCE OF 11225 AND 11345 ACCESSIONS OF ANDROGRAPHIS PANICULATA

Sodicity tolerance of two Malaysian Andrographis paniculata germplasm accessions (11225 and 11345) was evaluated in artificially alkalinized soil using five exchangeable sodium percentage (ESP) levels (0 (control), 6.25, 12.50, 18.75 and 25). The experiment was conducted in a greenhouse at the Universiti Putra Malaysia, during 2005 – 2006. Both accessions were grown for seventy days in polyethylene bags filled with 1.5 kg soil of each treatment. Agronomical traits (height, leaves, branches and fresh and dry herb yield including, concentrations of Na^+, K^+, Ca^2+ and Mg^2+ and K^+/Na^+ ratio in leaf sap) likely to be affected by sodicity were measured. The adverse effects of ESP on growth, development and herb yield were larger at values of 18.75 and 25 than at 6.25 and 12.50. As compared to control, at an ESP 6.25 the mean values of plant height, number of primary branches per plant, primary branch length, number of main-stem leaves per plant, leaf length and width decreased by 14, 20, 27, 16, 14, and 4%, respectively, while with ESP 25 these variables decreased by 43, 70, 51, 39, 53 and 62%, respectively. Generally plants grown at an ESP level of 18.75 were not significantly different from those grown at an ESP 25. Compared to control and other sodicity treatments, plants grown in 18.75 and 25 ESP treatments had higher concentration of Na+ and lower concentrations of K^+, Ca^2+ and Mg^2+ and showed lower K^+/Na^+ ratio in leaf sap. With the exception of length and number of primary branches per plant, which remained higher for accession 11345, the difference among accessions in sodic soil treatments was not significant for other growth and yield variables recorded. On the basis of fresh and dry herbage yields per plant, this study suggests that sodic soils with exchangeable sodium above 12.50% were adversely effective for both accessions.