Effect Of Phthalanilic Acid On The Growth And Development Of Pepper

N-phenyl-phthalamic acid(PPA)is a novel plant growth regulator that can regulate the regulate the growth and development of crops.Field plot experiment showed that pepper,apple,cowpea and other crops exhibited good effect after spraying with phthalamic acid,such as,leaves thick green,growing well.However,so far,the mechanism of action of phthalamic acid is not clear,which limits its further popularization and scientific use.In this study,brassinolide was chosen as the contrast agent.Pepper plants were sprayed with different concentrations of phthalamic acid and the changes of plant growth physiology,stress physiology,yield and fruit quality were measured,to clarify its biological effects on crops and initially reveal its mechanism of action.The main findings are as follows:(1)Phthalamic acid could regulate the growth of pepper plants.Greenhouse pot experiments showed that,compared with the blank control,7 d,14 d and 21 d after treatment,the relative growth rate of pepper plant height increased by 55.56%,75.00% and 135%,respectively;net increase of stem diameter of pepper plant increased by 33.33%,50.00% and 25.93%,respectively;but there was no significant change in the total number of leaves;each survey period,the chlorophyll content increased by 16.33% ~ 32.28%.However,the field plot test showed that under the tested concentrations(133.3,200.0 and 266.7 mg·L-1),there was no significant difference in the relative growth rate of pepper plant height,net increase of stem diameter and the total number of leaves,compared with control,at concentration of 200.0 mg·L-1,the chlorophyll content increased by 3.60%~14.54%.Brassinolide also has a similar effect,its regulation is higher than phthalamic acid.(2)Phthalamic acid could induce pepper plant stress resistance enhanced.Greenhouse pot experiments showed that,compared with the blank control,after treatment with 200.0 mg·L-1 phthalamic acid,the content of flavonoids,total phenols and free proline increased by 7.58%~47.5%,8.77%~33.33% and 13.49%~152.46%,respectively;the content of MDA decreased by 13.72%~35.98%;the activity of POD and CAT increased by 27.47%~157.34% and 53.85%~115.13% respectively.The field plot test showed that,compared with the blank control,after treatment with 200.0 mg·L-1 phthalamic acid,the content of flavonoids,total phenols and free proline increased by 10.06%~21.19%,7.42%~16.95% and 241.26%~ 8.46% respectively;the content of MDA decreased by 28.58%~52.79%;the activity of SOD?POD and CAT increased by 2.31%~9.00%?4.20%~471.72% and 34.98%~121.19% respectively.Brassinolide also has a similar induction effect,but showed some differences in the content of free proline and the activity of CAT with phthalamic acid treatment.(3)Increase production.at the concentration of 200.0 mg·L-1,phthalamic acid has obvious effect of increasing yield,compared with blank control,the yield increased by 13.91%;at the same time,the average single fruit weight of pepper fruit was also changed after treatment with it,but the difference was not significant.The yield effect of brassinolide was higher than 200.0 mg·L-1 phthalamic acid.(4)Improve fruit quality.phthalamic acid treatment zone(200.0 mg·L-1),the content of vitamin C and soluble protein increased by 28.61% and 52.92%,respectively;but,compared with blank control,the content of soluble sugar and organic acid has no significant difference;the nitrate content increased by 34.97%;However,the accumulation in pepper fruit did not exceed the national standard.Brassinolide is superior to phthalamic acid in improving the fruit quality.As can be seen from the above,phthalamic acid has a good effect on the growth of pepper,can make pepper from vegetative growth to reproductive growth,and activate the enzymatic and non-enzymatic antioxidant system of pepper plants to improve stress resistance,and show a better yield effect.As a new and efficient plant growth regulator,phthalamic acid has a good prospect of popularization and application.