Effect of Soil Salinity on Growth and Biomass Attributes of Clonal Eucalyptus

The inland salinity areas are one of the major problems which are continuously expanding, depending on natural underground salt, unsustainable agricultural cultivation, low quality irrigation, industrial waste and human-induced salinization in the different part of world. Reforestation is one of the most practical and effective strategies to solve the problem of saline soil through phytoremediation. In this direction Eucalyptus tree cause remediation of saline and waterlogged soil in terms of lowering saline water table, using underground water. Different clones have different tolerance level. It was observed that clone no. 413 attained maximum plant height and collar diameter at all salinity levels whereas clone no. 288 was at lowest rank in plant height and clone no. 2070 lowest in collar diameter among the clones tested. When number of branches were calculated Clone no. 288 holds maximum numbers while clone no. 2070 was having least number of branches at all levels of salinity. Clone no. 2070 attained maximum total leaf area whereas Clone no. 413 recorded least total leaf area. Clone no. 288 remains best and Clone no. 2070 lowest in rank among all biomass parameters viz. Dry shoot, Dry root weight, Total biomass etc. except Root: shoot. In this reference clone No. 413 is best. Introduction Salt-affected soils, which are widespread in arid, semi-arid and coastal regions, reduce crop growth and yield. It is estimated that nearly 10 % of the total land of the world used for crop production is adversely affected by soil salinity. In India, the area with potential salinity soil is about 20 million hectare and about 7 million hectare is severely affected by salinity (Mohan et al., 2000). In Punjab 6.4 percent of total geographical area is affected by salinity (Sharma et al., 2011). In Southern Asia and the near East several million hectares of agricultural land are affected by salinity causing losses in food, fuel and industrial raw material production. High concentrations of salts have detrimental effects on germination and growth of seedlings at high salinity and plants differ in their sensitivity or tolerance to salts. The factor of high evaporation, transpiration and concentration of salts on soil surface coupled with greater inherent sensitivity to salt are responsible for failure of most species on saline soils. Plants other than traditional annuals i.e. trees and shrubs which generally have an EC threshold higher than most field crops can be grown and these lands can be changed into productive resource. This area can attain importance due to financial benefits from these trees grown for biodrainage and amelioration the degraded soils. These trees may provide fuel wood, fibre, fodder, timber and some have nutritive value for human consumption. Eucalyptus camaldulensis has been identified as a tolerant tree species to salinity and water logging, and has more than 85 % survival rate under saline soil conditions (Sandhu and Qureshi, 1986). However, the potential of Eucalyptus clones to survive and grow in the saline environments is not well known. Hence, the present study is a step in the direction to assess the effect of soil salinity on growth and biomass attributes of clonal Eucalyptus. Material and methods The study was carried out in the Research farm area of Department of Forestry and Natural Resources, Punjab Agricultural University, Ludhiana situated at 247 m above sea level and at 30° 45’ N latitude, 75° 40’ E longitude with mean annual rainfall 704 mm rainfall. Climate is sub-tropical to tropical with a long dry season from late September to early June and wet season from July to September. Soil was filled in iron containers of 60 cm height and 20 cm diameter, around 40 kilogram of soil is filled in each container by tapping 5 times after adding 5 kg soil for maintenance of uniform and normal bulk density, all the containers after weighing kept in trenches. Total 135 containers were filled for different treatment of salinity and three replications. Three different types of salts viz. Nacl, MgSO4, CaCl2 were used in different quantities following the method by Jackson (1967) to achieve desired salinity levels (control, 5, 10, 20 and 40 dsm2). Three commercial clones viz. 288, 413 and 2070 were collected from Prakrati Biotech Pvt. Ltd, Patiala (Punjab). Completely Randomized Design with three replications and plot size of three plants was used. The Observations are plant height (cm), collar diameter (mm), Number of branches per plant, total leaf area (cm2/plant), fresh and dry shoot weight (g/ plant), fresh and dry root weight (g/plant) and Total biomass (g/plant). All growth and biomass parameters were recorded during April 2012 and data was analyzed with CPCSs software using Complete Randomized Design. The height of the main shoot was recorded from the ground level to the apex of the leading shoot. The average numbers of branches per plant were recorded on the basis of one plant of each clone selected randomly at different salinity levels from each replication. One plant of each clone of each salinity level was selected randomly. Further in each plant 10th, 11th and 12th leaves were selected for leaf area measurement by using portable leaf area meter (CID 110, CID Inc., USA) and the average value was multiplied by total no. of leaves a plant to calculate total leaf area. This was recorded in the month of April 2012. One plant (selected randomly) of each clone from each salinity levels and each replication and uprooted for biomass and other parameters. The shoot portion was separated from the root and it was weighted on an electronic balance to get fresh shoot weight. The shoots were dried in hot air oven at 80 ± 2 °C for till constant weight. The root portion, which was separated from shoot, was weighed on an electronic balance to get fresh shoot weight. The total biomass on dry weight basis was obtained by adding the dry shoot and root weight of respective plants. Results and Discussion Saline irrigation treatment at five levels were applied (control, 5 dSm-1, 10 dSm-1, 20 dSm-1 and 40 dSm-1) out of these five treatments eventually two highest salinity levels viz. 20 dSm-1 and 40 dSm-1 led to death of seedlings, these were lethal levels for Eucalyptus spp. Different clones showed variations in growth