Water Mangement Of Flax Under Different Sowing Dates:

Adel Youssef Salib

Two field experiments were carried out at the farm of Agric. Res.Center, Giza, Egypt, during 1993/1994and 1994/1995 seasons to manageflax irrigation (scheduling irrigation according to the Class A panevaporation records) under three sowing dates. The effect of sowing datesand irrigation regimes on flax yield and its components, oil content, sometechnological character of fibers, and the crop water use were studied. Also,the potential evapotranspiration and Class A pan relation to climate andcrop water use were estimated.Flax cultivar, Giza 8 a double purpose variety was used in bothseasons. The experimental design was split-plot with four replications.Sowing date treatment were arranged at random in the main plots and theirrigation regunes (scheduling irrigation) treatments were assignedrandomly with the sub-plots. The sub-plot area was 10.5 m2 (3.0 x 3.5 m)and each sub-plot was isolated by leaves 1.2 from other plots to avoid thewater lateral movements during irrigation. The experimental treatmentswere as follows:A. Sowing dates1. Early sowing2. Medium sowing3. Late sowing(October 2o&b)(November 1dh)(December Ill)The period between intervals were 3-weeks.B. Irrigation regimes11: Irrigation at 0.8 accumulative pan evaporation (APE)h: Irrigation at 1.0 accumulative pan evaporationh: Irrigation at 1.2 accumulative pan evaporation:4: Irrigation at 1.4 accumulative pan evaporationThe Class A pan used in the recommended type by the World MeteorologicalOrganization. It located very close to field and all factors affecting its records wereconsidered. The available soil moisture in the soil profile from soil surface til145.0em depth has been converted to units of water depth in mm and was found to be82.0 mm. The crop plants were irrigated when the water balance in the root zonereached zero, i.e. irrigation when the accumulative pan evaporation recordsmultiplied by the rates 0.8, 1.0, 1.2 or 1.4 are equal to the available soil moisturecontent or to 82.0 mm.The soil was clay loamy with pH of 7.4 Flax seeds were broadcasted at therate of60.0 kg/fed. Calcium super phosphate (15.5 P20S) was applied at the rate of100 kgslfed before planting. Nitrogen fertilizer was added in the form of urea(46.0% N) at the rate of 70 kg N/fed. in two doses. The normal cultural practicesfor growing flax were used during the two seasons. Irrigation regime treatmentswere applied after the first irrigation till the end of the growing season.Characters studied:L Yield and yield components1. Total plant height (em).2. Technica1length (ern).3. Number of fruiting branches/plant.4. Stem diameter (mm).5. Capsules number/plant.6. Seeds number/plant.7. Seed yield/plant (gm),8. lOOO-seed weight (gm)_ .._----1289. Straw yield/plant (gm).10. Seed yield (Kg/fed).11. Straw yield (Kg/fed).12. Fiber yield (Kg/fed).II. Oil content1. Oil percentage in seeds (%)2. Oil yield (kgslfed)ID. Technological properties offiben1. Fiber percentage, (%)2. Fiber length (em),3. Fiber strength (RKm.),4. Fiber fineness (N. m.)IV. Crop water use:1. Actual evapotranspiration (ETc)i. Seasonal ET (em}ii. Daily ET rates (mm/day)2. The Class A pan evaporation studies:i. Pan evaporation and some climatic factors relations.ii. Pan evaporation and actual daily Et rates relation3. Potential evapotranspiration (ETp)i. Monthly ETpii. Seasonal ETp4. Crop coefficient (Kc)5. Water use efficiency (WUE)i. WUE in kg seeds/m” water129ii. WUE in kg fibers/m’ water.The main results can be summarized as follows:I. Yield and yield components:A. Effect of sowing dates:1. Sowing flax early on October 2