Abstract:
Shortage of water resources and increasing demand to consumption of this scarce resource, leads to some noticeable limitations. On the other hand, population growth and consequently, increasing demand for water in arid and semi arid regions , needs production in exchange of little amount of water consumption. To approach this objective, an experiment in the complete randomized blocks carried out in four replications for cumin plant growing in Zabol, southeastern Iran. Experimental treatments included irrigation periods at three levels. Then using CROPWAT model, the water requirement of the plant is met. Analyzing the data resulted from production gathered in different times of irrigation and consumption of water in the three times irrigation case with sound efficiency (1750m3/ha), is more little than the water amount which is simulated by the CROPWAT model in 2003 (6070 m3/ha) and (5363 m3/ha) in 2004. It then showed that this model is not effective in determining the water requirement of cumin at this region.
Machine summary:
Analyzing the data resulted from production gathered in different times of irrigation and consumption of water in the three times irrigation case with sound efficiency (1750m3/ha), is more little than the water amount which is simulated by the CROPWAT model in 2003 (6070 m3/ha) and(5363 m3/ha) in 2004.
The CROPWAT model is used in this study to evaluate the minimum irrigation under the different circumstances from water, soil and plant resources.
The CROPWAT model developed by FAO (1992) is a relatively simple computer- based model of water balance for management and planning of irrigation which is able to simulate the water stress condition of plant and evaluate its effect on the yield reduction.
Meanwhile, Tavoosi (2000), by studying the effect of different methods of irrigation on cumin yield , reported that water potential of this plant at the end of growth period reached to - 30 Bar but any effect of wilting in the plant was not reported .
5 0 Coefficient of variation (%) Non significant in: ns Significamt in 5%: * Significant 1%: **The results also showed that there is no significant differences between treatments of I2 and I3; which shows that irrigation in final phase of growth(filling of plant seeds), not only had no effect on increasing of the yield but also caused decreasing it somehow.
The effect of water shortage in decreasing yield of cumin seed and being ineffective at the final phase, is also reported in the works of Aminpour and Mousavi (1995) and Tatary (2004).