Document Type : Research Paper
Abstract
This experiment was conducted in the province of Sulaimaniyah to study the effect of irrigation scheduling on a pepper product in plastic houses. The pepper was planted on 29/04/2011 and a month later, irrigation treatments applied in intervals of (2 , 3 and 4)days with three replicates on F1 Luany, Barcelona species. Water was added through drip irrigation system. For calculation of actual evapotranspiration (ETa) water balance equation was used, while for reference evapotranspiration (ETo) these equations were used; Class A pan evaporation, Hargreasev, penman-monteith, Blaney-Criddle and through (ETa) and (ETo), the crop coefficient (Kc) was found using the general equation of the crop evapotranspiration (ETc) equation. The results show that the amount of ETa for the treatments (9 , 3 and 4) days were (1117 , 776 and 618)mm respectively, while the depth of the added water was less than ETa by a deplete of soil moisture content (28 , 45 and 65)mm, an increase in (ETa) cause an increase in the yield and diameter of pepper crop, while there was no any significant effect on length of the product, dry matter and the depth of the vertical and horizontal roots. The yield response factor (Ky) was determined by using the Stewart equation and it was (0.54) between 2 and 3 days and (0.95) between 2 and 4 days and this shows that the yield response to deficit irrigation more between treatments 2 and 4 days, comparison to treatments 2 and 3 days, so it is advisable interval period of 2 days to 3 days compared with the interval of 2 days to 4 days. This refers to the possibility of using the value of 5.50 mm/day instead of 8.19 mm/day as reduction of yield was less important than evapotranspiration reduction. The values of water use efficiency (WUE) were 5.24 and 6.31 and 5.43 kg/m3 for treatments 2, 3 and 4 days, respectively. The average value of (ETo) for all mathematical models used 6.88, 7.12, 7.10, 5.34 and 3.75 mm/day for the month of June, July, August, September and October respectively, and can use the value of 7.0 mm/day as reference evapo- transpiration with a rate of 0.109 standard deviation for the months of June, July and August. As for the value of the crop coefficient (Kc) it is between 1.20 and 1.36 for Class A pan method and the Penman-Monteith method, respectively, and can use the value of 1.27 as average crop coefficient for pepper crop in greenhouses
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