India: Effect of different methods of irrigation
India: Effect of different methods of irrigation, and levels of irrigation and fertilization on morphological and physiological parameters in oil palm
A summary of paper published in the International Journal of Oil Palm 2: 27-30, 2001
Courtesy of Netafim University
Reddy, V.M., Sarma, K.N., Suresh, K., Rethinam P., & Nair, S.
National Research Center for Oil Palm, Pedavegi, Andhra Pradesh, India
Oil palm (Elaeis guineensis) is by far the most efficient oil producing crop. It is grown mainly in South-East Asia, Malaysia and Indonesia, under rain fed conditions. In this traditional growing region the annul rainfall may vary from well distributed 2000 mm to a seasonal deficit of 600 mm, which may be compensated by irrigation. In India the crop was introduced to regions where rainfall is about 1000 mm and poorly distributed during the year, requiring additional water to satisfy the water requirement of the crop. Consequently, water must be added by irrigation in order to obtain optimum growing conditions. However, there is a lack of data on the response of the crop to water under the conditions of Andhra Pradesh in India.
The objective of the present study was to evaluate the response of oil palm during the pre-bearing period to irrigation methods, quantities of irrigation water and levels of fertilizer application. There were three treatments of each of the variables, using a two year old oil palm plantation at the NRCOP, in Pedavegi, a village in the North-East of Andhra Pradesh. The irrigation methods tested were drip, micro-jet and basin; the irrigation water applied was based on potential evapotranspiration including canopy area (IW/CPE = 1.0, 0.8 and 0.6); the fertilizer applied was three levels of NPK: 0.9 N, 0.45 P2O5 and 0.9 K2O kg/tree/year, two times and three times these amounts. The morphological variables measured were: canopy area, plant height and girth, number of leaves produced per year, leaf area and leaf weight. In addition mid-day physiological parameters were also evaluated (photosynthetic rate [Pn], transpiration rate [E], stomatal conductance and water use efficiency [Pn/E]).
The only significant morphological differences found were among the irrigation methods, while there were no significant differences due to water or fertilizer quantities applied. Drip and micro-jet irrigation resulted in about the same values of plant height (4.03 - 4.28 m) and girth (1.89-1.84 m), number of leaves (27.1-26.5); leaf area (1.56-1.25 m2) and leaf dry weight (2.36-2.62 kg), while basin irrigation resulted in significantly lower values (3.66, 1.51, 23.0, 1.10, 1.77, respectively). Both drip and micro-jet resulted in higher levels of photosynthesis, transpiration rate and stomatal conductance than basin irrigation, while water use efficiency was better with drip irrigation (4.57 μmol CO2 per mmol H2O) compared with micro-jet (3.62) and basin (4.07).
The better results obtained with drip irrigation was due to more efficient application of water to the root system, thereby reducing evaporation and deep seepage losses, and to better water utilization by the shallow root system of oil palm. The minor differences obtained in all morphological and physiological parameters among the water and fertilizer treatments (although the drip and micro-jet resulted in slightly better values than basin) were most likely due to the age of the trees. As the trees grow and their water and fertilizer requirement increase, the advantage of the drip and micro-jet would become more apparent.
The research results show that contrary to prevailing belief that oil palm requires large quantities of water that can be supplied only by basin irrigation; good or better growth can be obtained with drip and micro-jet irrigation methods.
Key words: Drip irrigation, basin irrigation, evapotranspiration, fertilization, fertilizer requirement, micro-jet irrigation, morphological parameters, oil palm, photosynthetic rate, physiological parameters, root system, transpiration rate, water requirement, water use efficiency
Geographic terms: India-Andhra Pradesh, Indonesia, Malaysia