Research On Water And Salinity Transportation Of Sand Cultivation Watermelon By Brackish Water Nutrient Solution

For rational use of brackish water and brackish water irrigation of crops cultivated in sand, The changes of the cumulative irrigation amount and wetting front transport distance versus infiltration time were analyzed through brackish water infiltration experiments under different salinity,irrigation amount,dripper spacing firstly,as well as sand water content and electrical conductivity after infiltration.Then the changes and rules of water-salt transport were analyzed through sand cultivation watermelon test by different salinity brackish water nutrient solution.The results of brackish water infiltration experiment showed that:1.With the increase of cumulative irrigation amount,the wetting front distance in horizontal direction was greater than in vertical direction during early infiltration stage,initial infiltration rate was larger and gradually decreased.There was a good power function between the accumulative irrigation amount and infiltration time,as well as wetting front distance,and sand water content in wetting front changed heavily.2.Electrical conductivity and sand water content near surface were mainly influenced by water quality, As the salinity increase its value is significantly higher than control.3.Under different irrigation amount,the greater amount of irrigation through the soil,the larger sand moisture content,so leaching effect is also obvious,salt content of each sand layer within 40cm was no difference between maximum and minimum irrigation amount,But salt accumulation occurred below 40cm;4.Under different dripper spacing,salt content of each sand layer was lowest in 20cm treatment,pH is relatively small,moisture content was highest within 30cm taproots.The results of sand cultivation watermelon by brackish water nutrient solution showed that:1.Sand moisture content of each treatment generally increased with the increase of sand layer depth during the whole growth period. Except T3,moisture content of the rest treatments increased with increasing depth of sand layers rapidly during blooming and fruit setting stage,while increased slowly during full fruit stage and harvest period.T3 treatment had dramatic changes in the moisture content of the 30cm below sand layer during the whole growth period,and higher than the other treatments.brackish water treatments Moisture content of each sand layer in brackish water treatments were higher than the control, and moisture content of T3 each sand layer is much higher than other treatments.2.Salt content changes tendency o.ver time at different sand layers are similar in brackish water treatments,total salinity in 0-15cm changes significantly,0-30cm changes secondly,0-45cm changes smallest.During the fruit setting stage,Salt content within 30cm taproots of CK is much lower than the brackish water treatments,and salt content below 15cm sand layer increases with increasing of salinity;Salt content at different sand layers of all treatments reach the lowest value at full fruit stage.but significantly increase during harvest period,T2、T3 with a maximal increase slope,the smallest increase in control. During the whole growth period, pH change of CK、T1、T2 treatment are similar,T3 treatment has not been reduced, basically has been increased.3.Na+、K+(except harvest period)、Cl"(except blooming period)、SO42-、HCO3- ion content in different sand layers were lower than the initial value during growth period,while Ca2+、Mg2+ total content was much higher than the initial value,CO32-ion from scratch; Both Na+and Cl- total content in sand increased with the increasing degree of treatments mineralization.The Na+ total content of T3 was always higher than that of other treatments.Na+、Cl- content had same distribution within 30cm sand layers, the content of each layer increased with the mineralization increasing.Na+ content of each treatment during harvest stage was much higher than that of other stages. Compared with CK, Ca、Mg ion total content of sand in brackish water treatments decreased with the mineralization increasing.HCO3 content increased first and then decreased, finally increased again. At the maximum and minimal peak, its content increased with the increase of mineralization.SO42-、K+ content increased with the salinity had no significant variation.4.With the increase of brackish water mineralization,Heigh、stem diameter、leaf area growth of watermelon plants were significantly inhibited,resulting in photosynthetic capacity decreased, leaf membrane permeability,MDA、Proline content increased,the enzyme activity increased gradually.T1 growed even better than Control.5.Brackish water treatments improved watermelon quality,With the increase of treatment salinity.soluble solids,Vc content increased,while organic acid content decreased,total soluble sugars higher than the control.But the single fruit weight and yield of watermelon significantly decreased.The single fruit weight,yield was highest in T1 treatment.Compared to the control,T3 production reduced by 53.75%, T2 reduced by 18.54%, T1 increased by 9.76%.