| The unreasonable irrigation method in Hexi Oasis District has seriously affected the utilization efficiency of water resources in the region.With the continuous expansion of artificial Chinese herbal medicine planting area,the existing water resources in the region have been difficult to meet the demand for agricultural water.Therefore,in order to realize the efficient utilization of water resources and further increase the yield of medicinal materials in Hexi oasis region,it is urgent to carry out systematic experimental research on the theory of water saving and regulation of medicinal crops.From May to October,2018,the experimental study on the response of Radix Isatidis to water deficit under mulched drip irrigation was carried out in the Yimin Irrigation Experimental Station of Sanbao Town,Minle County,Gansu Province.The whole growth period of Radix Isatidis was divided into seedling and nutrition growth,fleshy root growth,fleshy root maturity,Sufficient irrigation was maintained at seedling stage and fleshy root stage,and water deficit irrigation at different levels was applied at the remaining two growth stages.There were 9 water deficit irrigation treatments and 1 full irrigation treatment at the whole growth stage,The effects of different water treatments on growth indexes were analyzed.The water consumption of the Radix isatidis was calculated by water balance method.The water consumption,yield,quality and water use efficiency of Radix Isatidis under the condition of deficit irrigation were analyzed.Jensen and Blank were constructed.The model fits the relationship between water consumption and yield at different growth stages of Radix Isatidis under deficient conditions,and obtains the water production function of Radix Isatidis in this area,which aims to provide a theoretical basis for high-yield and high-efficiency irrigation of Radix Isatidis.The research results are as follows:(1)Under the membrane drip irrigation water deficit treatment,the growth indexes of plant height,main root length,main root diameter and leaf area index of CK were kept at a high level,The effect of mild water deficit on the growth dynamic index of Radix Isatidis in vegetative growth period was not significant(P>0.05),but the moderate and severe water deficit in vegetative growth period caused a significant decrease in the growth index(P<0.05).(2)The mild water deficit treatment had no significant effect on the dry matter accumulation of Radix Isatidis(P>0.05).Moderate water deficit inhibited the accumulation of dry matter in Radix Isatidis,and the effect of severe water deficit was significant(P<0.05).In the vegetative growth,the dry matter accumulation(WD1,WD4 and WD5)increased by 2.84%~3.44%compared with the control CK,the difference was not significant,The dry matter accumulation of the remaining treatments decreased by different extents compared with CK,and the decrease increased with the increase of the degree of deficit;when entering the fleshy root growth,the dry matter accumulation of WD1 and WD2 increased by 7.32%and5.93%,respectively,compared with CK,the difference was not significant;At the fleshy root maturity,the dry matter accumulation of WD1 was still the highest,and the dry matter accumulation of WD4 was 2.68%higher than that of the control CK.The cumulative rate of dry matter in the whole growth period of Radix Isatidis showed a large single-peak change in the middle of the growth period(0.386g/d in the fleshy root growth period),and before the growth(0.148g/d)and later.The effect of mild water deficit on the biomass of aboveground and underground parts of Radix Isatidis was not significant,and the moderate and severe deficits were significant.For example,the aboveground biomass of WD1 was the largest(14.03g),which increased by 1.23%compared with CK,root dry weight increased by 7.02%;At the same time,mild water deficit treatment can regulate the accumulation of photosynthetic products to the roots to increase the root-shoot ratio of Radix isatidis,while severe water deficit treatment significantly reduces the root-shoot ratio,such as compared with the root crown of CK,the WD8 and WD9 was significantly reduced by 9.05%and 7.79%.In addition,the mild water deficit in the vegetative growth period could significantly increase the Radix Isatidis harvest index,and the harvest index of WD1 was 0.67.(3)Water consumption of Radix Isatidis in different growth stages was as follows:the water consumption of vegetative growth stage and fleshy root growth stage was larger,fleshy root maturity stage was second,and seedling stage was the smallest.Water consumption modulus was above 32.92%,32.85%,16.33%and 9.42%respectively.The water deficit treatment in different growth periods significantly(P<0.05)reduced the water consumption of Radix Isatidis,and the water consumption decreased with the increase of the degree of water deficit.The water consumption of mild to moderate continuous deficit water treatment was significantly reduced by6.01%~7.92%compared with CK,while that of severe water deficit water treatment(WD3,WD8 and WD9)was the lowest,which was significantly reduced by9.86%~12.98%compared with CK.(4)Mild water deficit in vegetative growth period was beneficial to increase the yield of Radix Isatidis,while moderate and severe water deficit leaded to significant decrease in yield(P<0.05).Among them,WD1 had the highest yield(8475.38kg/hm~2),which was 1.51%higher than that of control CK.Secondly,WD4 was slightly lower than control CK,but the difference was not significant(P>0.05),but the yields of severe water deficit treatment(WD3,WD8 and WD9)were significantly lower than the control by 16.32%~30.72%;(5)Mild and moderate deficient treatment can increase the content of active ingredients in Radix Isatidis,which is beneficial to the quality of Radix isatidis,while severe water deficit is unfavorable for the accumulation of active ingredients.The indigo content of Radix radicans in the vegetative growth period and the fleshy root growth period was slightly increased from 3.26%to 9.62%compared with the control CK,the difference was significant.(P<0.05),The indigo content of severe water deficit treatment(WD3,WD8 and WD9)decreased by 6.53%~7.18%compared with CK;The content of indirubin red in heavy water treatment(WD3,WD8,WD9)in the vegetative growth period was 12.80%~13.42%lower than that in the control CK,However,the content of indirubin red in mild and moderate continuous deficient treatment(WD4,WD5 and WD6)increased by 1.03%to 4.95%compared with the control CK.The effect of deficient treatment on the content of(R,S)-goitrin in Radix Isatidis was basically the same as that of indigo and indirubin.In nutrient and fleshy root growth period was mild to moderate continuous water deficit treatment(WD4,WD5 and WD6),The content of(R,S)-goitrin was significantly different from that of CK,with an increase of 4.58%to 7.92%.(6)The mild water deficit treatment significantly improved the water use efficiency of Radix Isatidis,and the yield was similar to that of the control CK.The irrigation water use efficiency and water use efficiency of WD1 and WD4 were significantly higher than CK by 10.29%and 8.98%,8.87%and 7.05%(P>0.05),respectively,while those of other treatments decreased in varying degrees.At the same time,under the condition of water deficit,the relationship between water consumption and yield of Radix Isatidis showed a quadratic function.When water consumption was 386.8 mm,the yield of Isatis indigotica was the highest(8193.96kg/hm~2).When water consumption was greater than that,the yield would not increase,but would decrease.(7)The correlation coefficient R of the water production function model of the Radix isatidis stage calculated by Jensen and Blank model is 0.981 and 0.998,respectively.Both of them can better reflect the relationship between the yield of Radix isatidis and water consumption,The water sensitivity index of Radix Isatidis at different growth stages obtained by the two models is,from large to small,followed by fleshy root growth stage,vegetative growth stage,fleshy root maturity stage and seedling stage. |
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