| A field experiment and column simulation experiment were carried out to investigate effects of brackish water supplement irrigation on soil water-salt distribution,water consumption,growth,fruit yield and quality of watermelon on gravel-mulched field in the central arid areas of Ningxia.The water and salt transport laws of different brackish water amounts was studied under the condition of without watermelon cultivation.At the same time characteristics of soil water and salt transport with gravel mulch and bare land were compared and analyzed under the condition of the same brackish water was irrigated in the column experiment.The results showed as follows.(1)The soil water content of gravel-mulched field watermelon root distribution area was increased by brackish water supplemental irrigation,meanwhile water consumption and brackish water irrigation amount tend to increase linearly.(2)From the aspect of soil salt change during the whole growth period of watermelon,it changed a little with treatment of CK;soil salt content of 0-100 cmincreased by 16.90%with irrigation quota of 15 m/667m2 And those decreased by 9.24%and 14.72%with irrigation quota of 30 and 45m3/667m2,irrespectively.HCO3-mainly concentrated in the shallow or main root area of soil,and the average reduction of 4.47-24.75%during the whole growth period of watermelon.The contents of HCO3-,Cl-,S042-,,Mg2+,Na+ in the 0-40 cm soil layer with irrigation quota of 15 m3/667m2 were significantly higher than those with others.It indicated that ions content in the 0-40cm soil layer decreased with the treatment of 30 and 45 m/667m.Ca2+ content fluctuated less in 0-100 cm soil layers,and decreased with each irrigation treatment.(3)Compared with non-irrigation,brackish water irrigation promoted the growth and improved the fruit yield of watermelon production,especially with irrigation quota of 15 m3/667m2.And the range of increase yield was at 20.2%to 50.9%.But no-irrigation treatment increased the value of SPAD.Water use efficiency of watermelon showed a linear decrease trend with increase of brackish water amount and it got highest value of 12.3kg/m3 with treatment of 15 m3/667m2.The vertical and horizontal diameter of watermelon and Vc content increased with the increase of irrigation amount,but the content of soluble solid and the pH value of melon were increased with no irrigating treatment.The difference of total acidity and soluble sugar content in watermelon wa not significant.(4)It could be found that soil water content of the upper soil layer decreased gradually and that was increasing after irrigation during the experiment period.Soil water content of surface layer(especially 5 cm soil layer)was more stable when the irrigation amount was higher.Soil salt content peak moved downward gradually during the experiment period with gravel mulch and brackish water irrigation and soil salt content of the surface layer(especially 5cm soil layer)had a tendency of decreasing.Wet front and soil salt content peak continued to move downward with increase of brackish water amount.Compared with no gravel mulch treatment,gravel mulch had a significant effect on water retention and soil salt inhibition in surface soil layer through the independent sample T-test. |
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