EFFECT OF ALKALINITY ON GERMINATION, GROWTH AND NITROGEN-CONTENT OF WHISTLING PINE (CASUARINA-EQUISETIFOLIA) AND BEEFWOOD (C-GLAUCA)

An experiment was conducted during 1987 under laboratory and greenhous e conditions to study the effect of different levels of alkalinity on germination. growth and nitrogen content of whistling pine (Casuarina equiselifolia Forster & G. Forster) and beefwood (C. glauca Sieb. ex S preng.). Germination in both the species was delayed and reduced with the increase in pH. C. equisetifolia was more tolerant to alkalinity t han C. glauca at the germination stage. The shoot and root weights of Casuarina spp were significantly reduced at pH 9.8 than at pH 8.2 in a lkaline soil. However. at lower pH levels both the species showed incr eased growth. C. equisetifolia showed 15% increase in shoot yield in s oil having pH 8.2 compared with the soil having normal pH. A further i ncrease of pH to 9.0 decreased the shoot yield by 26% compared with pH 8.2. However in C.glauca, after 230 days of alkali stress, 115% incre ase in shoot yield at pH 8.2 was observed compared with the normal soi l, which decreased further by 35% at pH 9.8. The total nitrogen conten t of C. equisetifolia was greater than of C. glauca, through the N con centration (%) was mom in the latter species. The total N content for both species decreased significantly at pH 9.8 compared with pH 8.2.