Growth and Biomass Accumulation in Eucalyptus Camaldulensis Irrigated at Different Water Regimes in an Arid Sandy Plain of India

Abstract

A trial was initiated in July, 1995 to study the performance of Eucalyptus camaldulensis under different irrigation regimes on an arid sandy plain. Six treatment combinations of water quantity (W₁ and W₂) and watering frequency (I₁, I₂ and I₃) were imposed. Irrigation schedule was maintained on the basis of IW/CPE ratio (Irrigation water/cumulative pan evaporation). Plant growth and biomass at 40-month age was high in I₃W₂ treatment where 45/ 60 mm of water per irrigation was applied with a total of 1935 mm (36 applications). Inspite of receiving more irrigation water, (2040 mm in 53 applications) growth and biomass accumulation by plants in I₃W₁ was less in comparison to plants in I₃W₂ treatment. Irrigation increased total dry biomass by 9 fold in I₃W₂ treatment over I₁W₁ treatment. Analysis of variance showed significant difference both at 5% and 1% level between the treatments. Incremental growth followed more or less the same trend in the first and second year but in the third year no significant variation was observed among treatments signifying absence of any treatment effect. More than six fold higher water use efficiency (WUE) was recorded in I₃W₂ over I₁W₁. Soil organic matter and electrical conductivity decreased significantly in all the treatments whereas, significant increase in pH was observed after 40 month of plant growth. Results of the study show that quantity of water added per irrigation is more important than the total irrigation input. I₃W₂ treatment provided more soil volume with favourable moisture condition for roots where wetted rooting zone was more and thus resulted in better growth and biomass production.