The Study Of Water Requirement Law And Yield Effects Of Onion Under Drip Irrigation With Plastic Film Mulch In Arid Area

The field experiments for drip irrigation underneath mulching film of onion was carried outin minqin experimental station of water conservancy science research institute in Gansu provincefrom May to September in2011. The water consumption pattern, soil moisture dynamics,crop-growth dynamics, physiological index, water use efficiency, irrigation water use efficiency,yield effect and economic benefit were mainly studied in this paper. Four treatmentsT₁(2490m³·hm^-2)、 T₂(27603·hm^-2)、 T₃3(3030m·hm^-2)、 T₄(3300m³·hm^-2)、 T₅(3570m³·hm^-2) andCK(8100m³·hm^-2) based for the different irrigation quotas in the whole growth stage were applied.The results were as follows:1. In the whole growth period of the onion, soil moisture change trend of onion wasbasically the same in different growth stages in drip irrigation underneath mulching film,and thetrend was first increase, then decrease, and then increase again with soil depth increased inseedling stage and six leaf stage. However, it was basicly first increase and then decrease withsoil depth increased in the bulb of swollen stage and was first decrease and then increase in thebulb filled expands the period..2. The soil temperature in different depthes of different treatments were rised between8:00and14:00, however, the maximum soil temperature of different depthes were different. The dailychanging amplitude of5cm,10cm and15cm were large, and were gentle changed in20cm and25cm. Comparied with non-mulching, there was obvious effect to kept temperature and humiditywith film mulching.3. For conventional irrigation CK and drip irrigation treatments underneath mulching filmin the whole growth seasons, plant height among all the treatments grew slowly in seeding stageand bulb of swollen stage, and was rapid growth in six leaf stage, and tended to be stable state inthe bulb filled expands the period. Compared conventional irrigation CK with drip irrigationtreatments underneath mulching film T₁, T₂,T₃and T₄in the whole growth seasons, there weresignificant difference and even very significant difference. For conventional irrigation CK anddrip irrigation treatments underneath mulching film in the whole growth stage, the changingtrend of LAI was the single-peak curve.The peak value and the maximum difference of LAI wereappeared in the bulb of swollen stage among different treatments.4. The maximum of water consuming intensity among all the treatments was conventionalirrigation CK in the whole growth period. Water consuming intensity of T₅was the biggest in drip irrigation treatments underneath mulching film.The maximum of Water consuming intensityappeared in six leaf stage among all the treatments. The Minimum of Water consuming intensitybetween T₁and T₂appeared in the bulb of swollen period. The Minimum of Water consumingintensity among T₃,T₄,T₅and CK appeared in the bulb filled expands period.5. Water use efficiency for drip irrigation underneath mulching film of onion was thesingle-peak curve which was first increases and then decreases in the whole growth period. Thesignificant analysis showed that the water use efficiency among different treatments existedsignificant difference and even very significant difference.6.Among all the treatments, The highest yield was not conventional irrigation treatment CKwith the greatest water amount. Howere, was drip irrigation underneath mulching film T₄.7. Through analyzing the economic benefit of onion, the hightest net income was T₄.3300m³/hm²can be popularized and applicated under the local agricultureal productioncultivation and technical conditions.