Spring Tea Shading Cultivation And Environmental Regulation Technology From The Final Harvesting Period

As the temperature rises rapidly,the internal and appearance quality of raw materials of tea decline from the final harvesting period of spring tea and shorten the picking period.In order to keep the quality of tea and prolong the picking period of spring tea,shading and spraying and other small environmental cooling measures can be used.In this paper,we designed and developed the shade net and spray cooling system;and analyzed the changes of environmental factors such as temperature,relative humidity,light and soil temperature inside and out of shade net;and analyzed the effects of shading on the growth of new tea leaves and leaf quality;Simulation and test on the effect of spray cooling when shading was carried out,thus determine reasonable layout of the nozzle space;Finally,the method of shade net and spraying on cooling environment condition is put forward,which has important guidance significance for maintaining the quality of spring tea and prolonging the picking period.The main contents and results of the study are as follows:(1)Design of the shade net and spray cooling systemThe shade net skeleton is made up of column connected by wire rope;its length is 48 m along with a span of 6 m,a height of 2-2.5 m and each column spacing of 8 m.Three different shading treatments can be set up,two 2.0 m high treatments,one 2.5 m high treatment with two shading rate of shade net,respectively,40%,60%.The tea variety is Mao Lv,five years old.Spray system is made up of the PE pipe connected by the nozzle along the middle the shade net skeleton,the nozzle can be set at different heights;spray host model: 3WZ-860,micro-mist nozzle model: TW1510.(2)The effect of shading on its inside and outside environmental factorsAccording to different shading and shading height,different shading treatments were set up.The inside and outside dynamic changes of shade net of air temperature and relative humidity environmental factors were measured and compared.Three shading treatments are: 60% shading rate +2 m shade height(T1),40% shading rate +2 m shade height(T2),40 % Shading height of +2.5 m(T3),none-shading(CK).The trial period(from the end of April to the end of May)was divided into early,mid and late.The results were compared with the conventional picking period(from the beginning of April to the end of April).The results show that: compared with CK,the daily maximum air temperature(the average is 2.17 ?)of tea crown was decreased;the daytime average temperature(the average is 3.56 ?)of soil surface with different shading treatments were significantly decreased;the average daily temperature(the average is 1.19 ?)of soils(depth of 10 cm)with different shading treatments was significantly decreased;and the higher of the shading rate,the greater of the temperature decrease;shading can increase the relative humidity of tea crown,the higher of the shading rate,the greater of the relative humidity increase;T1 treatment maximum increased by 7.03%.Compared with CK,the maximum temperature of leaves of T1,T2 and T3 treatment decreased by 2.13 ° C,1.28 ° C and 0.94 ° C,respectively.Comparison of T2 and T3 treatment with the same shading rate,there was no difference between different shading heigh on the environmental factors.(3)The effect of shading on the growth and quality of tea leavesThe trail treatments were the same as(2).The growth status of tea leaves and tea twig,leaf photosynthesis and the quality of tea buds,etc,were tested.After shading,the results showed that: The new twig length and the roughness increased,T1 increased the largest,respectively 22.3% and 13.5%.As the shading rates increases,chlorophyll content and water content of buds increases.Compared with CK,the photosynthetic rate of T1 increased by 8.49%,T2 and T3 decreased.Compared with CK,T3 treatment can increase the content of water extract,polyphenols of tea and the ratio of polyphenols to amino acid;reduce the content of amino acid of tea,leading to it taste more thick,but more bitter.T1 treatment can increase the content of caffeine,reduce the content of water extract,and reduce the ratio of polyphenols to amino acid significantly,resulting in tasting light,but increasing the freshness,reducing bitter.(4)The effect of spray cooling on air temperature and humidity of tea crownAccording to the different shading rate,two spray treatments were set up;with the open environment as the control;the cooling effect of spraying on the tea crown was tested and compared with the different height(1.2 m and 1.5 m)of nozzles.Different height(1.2 m and 1.5 m)and different spacing(1 m and 1.5 m)of nozzles were simulated to determine a reasonable layout of the nozzle space.Spray cooling test showed that: it can significantly reduce the air temperature of tea crown under the shade net by 2.6 ?-6.8 ?.When the spraying height was 1.2 m,the air temperature of tea crown reduced more obviously and the relative humidity increased more obviously.The numerical simulation of spry cooling results show that: when the nozzle height is 1.2 m(0.3 m to the tea crown),and the nozzle spacing is 1.5 m,the cooling effect is better and the humidity is relatively low.It's better to use the methods of spraying on 60 s,off 30 to prevent the relative humidity increase too much.(5)Environmental regulation technology to prolong the picking period of spring teaThe cultivation with shade net of 60% shading for tea yield,is better to improve the tea garden environment and more conducive to the growth of tea.With the cultivation,the caffeine content is higher and the ratio of polyphenols to amino acid is closer to the conventional spring tea level in early;the amino acid content significantly in mid.So the cultivation method is expected to prolong the picking period of spring tea about 7d;using the method(height 0.3 m from the crown,nozzle spacing 1.5 m)of spray cooling under shade net,can further prolong the picking period of spring tea.