Effects Of Multi Walled Carbon Nanotubes Combined With KH₂PO₄ On Growth And Fruit Quality Of Summer Black Grape

【Objective】In order to explore the effects of multi walled carbon nanotubes（MWCNTs）on grape growth and fruit quality,the effects of different concentrations of MWCNTs spraying and the combined application of MWNTs and KH₂PO₄ on grape growth and fruit quality were studied to provide a theoretical basis for the application of MWNTs in agricultural production.【Method】In this experiment,9-year-old"summer black"grapes were used as materials.Respectively in the ear stage（15d after anthesis）,fruit expansion stage（35d after anthesis）and fruit coloration stage（60d after anthesis）,multi-walled carbon nanotubes were sprayed on the grape leaves.0 mg·L^-1（CK）,4mg·L^-1（M1）,8mg·L^-1（M2）,12 mg·L^-1（M3）,8mg.L^-1multi-walled carbon nanotubes mixed with 0.5%KH₂PO₄（MK）and0.5%KH₂PO₄ spray separately.The new shoot growth,leaf mineral element content,plant photosynthetic performance and fruit quality were measured.【Results】（1）Different concentrations of multi-walled carbon nanotubes with 7-21 days after treatment were promoted plant growth,grapes and spraying with multi-walled carbon nanotubes increased concentration of grape shoot length,leaf SPAD value,net photosynthetic rate（Pn）,transpiration rate（Tr）,stomatal conductance（Gs）presents a trend of reducing the rise,M1,M2,and M3 processing plant daily average net photosynthetic rate（Pn）compared with the CK increased by 8.64%,19.67%and 9.04%respectively.Chlorophyll fluorescence analysis showed that spraying multi-walled carbon nanotubes improves the PSⅡmaximum photochemical efficiency（Fv/Fm）and photochemical activity（ΦPSⅡ）potential and actual photochemical efficiency（Fv/F0）,had no significant effect on the initial fluorescence（F0）,P,K,B,Mg content in leaves increased significantly,the average weight of M1,M2,and M3 processing compared with CK increased by 3.4%,9.4%and 1.9%respectively.（2）After 7-35 days treatment,MWCNTs of different concentrations improved grape fruit quality.On the 35th day,M1,M2 and M3 treatments increased the soluble solids by 0.9%,6.2%and 3.1%,respectively,compared with CK.The ratio of solid to acid increased by 14.9%,32.2%and 15.4%,respectively,which accelerated the degradation of titratable acid.The fruit p H and average fruit weight of M2 treatment were significantly increased.On the 35th days,grape color index（CIRG）of M1,M2 and M3 increased by 11.0%,19.7%and7.9%compared with CK,and the content of anthocyanins in grape skins and the activities of PAL and CHI were significantly increased.（3）After 21 day,M2,MK,K compared with CK grape new tip length increased by 11.3%,14.0%and 6.9%respectively,leaf SPAD value increased by 19.1%,19.2%and 8.3%,respectively,plant net photosynthetic rate（Pn）,transpiration rate（Tr）,stomatal conductance（Gs）,PSⅡphotochemical efficiency（Fv/Fm）,the largest potential（ΦPSⅡ）and photochemical activity actual photochemical efficiency（Fv/F0）all have different degrees of ascension,Compared with CK,the contents of P,K,B,Fe and Mg in leaves of MK treatment increased by 9.8%,6.9%,24.0%,4.5%and 14.0%,respectively.The average single fruit weight of M2 and MK treatment was significantly higher than that of CK,and increased by 9.7%and 11.2%,respectively.（4）Different combination treatments（M2,MK,K）could effectively improve the internal quality of grape fruits at 7-35 day after treatment compared with water spraying（CK）.On 35th day after treatment,the soluble solids in fruits treated by M2,MK,K increased by 6.2%,11.1%and 5.1%compared with CK.The content of titratable acid decreased by 19.0%,10.5%and 4.8%,respectively.The p H value of fruits treated with M2 and MK was significantly higher than that of CK.On 35th day after treatment,grape color index（CIRG）M2,Mk and K increased by 7.7%,10.5%and 4.4%compared with CK.The content of anthocyanins in grape skins increased by 19.7%,22.3%and 11.1%,respectively.The activities of PAL and CHI related to anthocyanin synthesis were significantly increased.The chlorophyll degradation in pericarp was accelerated by different combination treatments from 7 to 35 days.After comprehensive evaluation of fruit quality indexes by principal component analysis,it was found that MK treatment had the best ability to improve fruit quality.【Conclusion】The application of MWCNTs as foliar fertilizer is beneficial to the growth and development of grape and improve grape fruit quality,and the effect of 8mg.L-1 concentration is the most obvious.The combination application of MWCNTs and KH₂PO₄ had the highest effect on grape quality improvement.