Effect Of Temperature And N On Nutrient Uptake Kinetic Characteristics In Litchi And Longan

The aim of this study was to investigate the effects of different temperatures and nitrogen on nutrient uptake by litchi and longan.The"Heiye"litchi seedlings,"Fuyan"longan seedlings and"Chuliang"longan seedlings were used to study the uptake kinetic parameters at different temperatures（10,15,20,25,30 and 35°C）and N forms（nitrate,1/2nitrate+1/2 ammonium and ammonium）.By fitting NO₃^-,NH₄⁺,H₂PO₄^-,K⁺,Ca²⁺,Mg²⁺,SO₄^2-and Fe³⁺and other nutrient segregant consumption curves,the kinetic parameters of litchi and longan absorption of each nutrient segregant were obtained,and the differences in the ability of roots to absorb nutrients were further compared.It can provide a basis for selecting suitable nutrient and nutrient combinations for different seasons（phenology）of litchi and longan.The results were described as follows:（1）Temperature,N form and their interactions had significant effects on the kinetic parameters of litchi absorption of various nutrient segregants.However,the interaction between temperature and nitrogen nutrition had no significant effect on the A_m（affinity）of Ca²⁺absorption by litchi.（2）In the temperature range of 10～20°C,the highest total A_m and the lowest C_min（ion compensation concentrations）were observed in the total nitrogen,H₂PO₄^-,Mg²⁺and Fe³⁺of litchi under nitrate.Under the nutrition of 1/2 nitrate+1/2 ammonium,litchi absorption H₂PO₄^-and K⁺has a larger I_max（the maximum absorption rate）.In ammonium,litchi absorbs Ca²⁺,Mg²⁺and SO₄^2-with a larger I_max,and at this time Ca²⁺and SO₄^2-have higher A_m and lower C_min.Under the nutrition litchi grows in the temperature of 20～25°C.Ca²⁺,Mg²⁺and Fe³⁺have larger I_max,and Mg²⁺has higher A_m and lower C_min at this time.Under the 1/2 nitrate+1/2 ammonium,litchi has the largest I_max for H₂PO₄^-and K⁺.In ammonium,the litchi absorbed K⁺,Ca²⁺and SO₄^2-had higher A_m and lower C_min,while Ca²⁺at 25°C has a big I_max.When the temperature is 30～35°C,the absorption of total nitrogen and Mg²⁺by litchi under nitrate has higher A_m and lower C_min,and has larger I_max for Ca²⁺and Fe³⁺.In 1/2 nitrate+1/2 ammonium,litchi has a larger I_max for total nitrogen,H₂PO₄^-and K⁺,and the highest A_m and lowest C_min for Fe³⁺.Under ammonium conditions,litchi had higher A_mand lower C_min for K⁺,Ca²⁺and SO₄^2-,and a larger I_max for SO₄^2-and Fe³⁺at 30°C.（3）The I_max of sputum absorption of NO₃^-was significantly higher than that of NH₄⁺.At the same time,NO₃^-has stronger A_m and lower C_min.（4）Temperature has a significant effect on the kinetic parameters of longan absorption of various nutrient segregants.N form only had no significant effect on the I_max of H₂PO₄^-,Ca²⁺and SO₄^2-absorbed by the longan.The interaction between temperature and N form had significant effects on the three kinetic parameters of H₂PO₄^-,SO₄^2-and Fe³⁺absorption in longan,but the effect on I_max of total nitrogen,and A_m or C_min of K⁺,Ca²⁺and Mg²⁺did not reach significant.（5）In 1/2 nitrate+1/2 ammonium,the absorption of total nitrogen,H₂PO₄^-,K⁺,Ca²⁺and Mg²⁺by longan was higher than that of nitrate,and C_min was lower than nitrate.In the temperature range of 10～15°C,longan has a large I_max for Fe³⁺,and K⁺and Mg²⁺have higher A_m and lower C_min.In 20～25°C,the longan has a large I_max for H₂PO₄^-,K⁺,Ca²⁺and Fe³⁺;longan has the largest I_max for H₂PO₄^-and Mg²⁺under 1/2 nitrate+1/2 ammonium.When the longan is in the temperature range of 25～35°C,under the nitrate the longan absorption of total nitrogen,K⁺,Mg²⁺and SO₄^2-has larger I_max,and has a higher A_m and lower C_min for total nitrogen,SO₄^2-and Fe³⁺.In 1/2 nitrate+1/2 ammonium,longan has a larger I_max than H₂PO₄^-,and has a larger I_max for other nutrient segregants,and for total nitrogen,H₂PO₄^-,Ca²⁺,SO₄^2-and Fe³⁺There is the highest A_m and lower C_min.（6）The I_max of NO₃^-absorbed by longan was significantly higher than that of NH₄⁺,but there was no significant difference in the absorption of I_max between the two forms of nitrogen in the longan at 10 and 20°C.When the temperature is 10～25°C,the longan is more than NO₃^-and the C_min is lower than NO₃^-for NH₄⁺.When the temperature is30～35°C,the longan has higher A_m and lower C_min for NO₃^-.（7）Under different nitrate and ammonium ratios,longan absorbed higher A_m for total nitrogen in 100%A（completely ammonium）and 15～25°C treatment,while C_min absorbed25%of total nitrogen in longan at any temperature.25%N（nitrate ammonium ratio 1:3）has a smaller value under nutrient treatment.Longan absorbed NH₄⁺at 10～15°C with larger I_max,higher A_m and lower C_min.At 20～25°C,longan absorbs NO₃^-with larger I_max higher A_m and lower C_min.When the temperature is 30～35°C,the preference of longan for the two forms of nitrogen parent segregants is not obvious enough.Under 75%N treatment,the I_maxof NO₃^-absorbed by longan had a large value.While the I_max of longan absorbed NH₄⁺had a larger value under the treatment of 25%N and 100%A.Conclusively,temperature,N form and the interaction between the two significantly affected the nutrient uptake of litchi and longan.Litchi prefers nitrate and has strong absorption capacity.Longan prefers to absorb ammonium at 10°C and has a large absorption capacity.At 25～35°C,it prefers nitrate and has a strong ability to absorb nitrate.The ammonium and nitrate mixed is more conducive to the absorption of nitrogen,phosphorus and potassium by litchi and longan than the single form nitrogen.However,ammonium is supplied separately at 15 and 25°C,and litchi has the strongest ability to absorb nutrients such as calcium,magnesium and sulfur.Applying a nitrogen fertilizer with a ratio of 1:1 to ammonium nitrate in the fruit expansion period and a nitrogen fertilizer with a ratio of 1:3 in the autumn shoot growth period is beneficial to the absorption of nitrogen by the longan.