M. Hebbara , M. V. Manjunatha , S. G. Patil , V. B. Kullgod , P. S. Minhas

Abstract

A field experiment was conducted to evaluate the performance of tree species in salinewaterlogged soils during 1991-1998 at Agricultural Research Station, Gangavati, Karnataka. Six tree species viz: Hardwickia binata, Sesbania grandiflora, Acacia nilotica, Dalbergia sissoo, Casuarina equisetifolia and Azadirachta indica and a grass (Pennisetum purpureum) was selected for the study. Tree performance was evaluated in terms of survival, height, diameter (dbh) and canopy width in different salinity blocks (range <5 to >15 dS/m). Effect of combined stress of shallow water table and salinity (SEWN) on various growth parameters after two years of planting was also studied. Based on various tree growth parameters, A. nilotica out performed all other species at all salinity levels followed by C. equisetifolia. Higher establishment and better growth rate made it more suitable for saline conditions. A. nilotica and D. sissoo exbibited regenerability under its own cover. Growth of tree species was strongly related to SEWN than to isolated stress of shallow water table or salinity.

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O. S. Tomar , R. M. Kumar , Raj K. Gupta , P. S. Minhas

Abstract

High salt concentrations in ground waters pose problems for raising nurseries of tree species under arid climates. Nursery bags should, therefore, be planted and maintained in a manner that either allows irrigation water to move the salts past these bags or reduce the salinity damage. Therefore, an experiments was conducted with Acacia nilotica as test tree where treatments consisted of combinations of (a) salinities of irrigation water (0.4, 2, 4, 6, 8, 10, and 12 dS.m^-1), (b) irrigation interval (2, 4 and 6 days) and (c) ratio of depth of irrigation water to cumulative pan evaporation (Diw/ CPE = 0.85, 1.00, 1.15 and 1.30) to achieve varying leaching fractions. The results did not show any potential benefits of maintaining high leaching fractions whereps decreasing irrigation interval to 2 days was observed to reduce salinity damages to some extent. A nilotica was observed to be more tolerant to salinity at germination than early seedling stage. With an Ect of 5.0 dS.m^-1 and slope of 19.5 % at seedling stage, this should be rated as moderately tolerant to salinity.

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