Dynamic Changes Of Mineral Nutrient Elements In Jackfruit Leaves

Mineral nutrient elements are essential for plant growth and development.In this study,the dynamic changes in contents of N、P、B、K、Ca、Mg、Fe and Zn in leaves of the 3 jackfruit varieties were analyzed to provide a theoretical basis for fertilizer application and nutrition diagnosis of jackfruit.The main results were as follows:(1)The content of N and P decreased throughout the year.Contents of N decreased gradually during bud germination and flowering,slowely during the stage of fruit expansion,and reached the lowest value at this stage.After fruit harvested period,the content was slightly increased;the range in contents of N throughout the year was 12-18.5 g/kg;The content of P increased rapidly at the period of leaf spreading and flowering,and then declined rapidly.At the fruiting stage,the content of the element decreased slowly.After harvesting of fruit,the content of the element was slightly increased,and the content throughout the year was maintained at0.006-0.017 %.(2)The content of K decreased slowly at the stage of bud germination and flowering.During the period of fruit growth,the content varied.From November to December,the content was maintained at 2400-2900 mg/kg.The content throughout the year was maintained in the range of 1700-3400 mg/kg.(3)The content of Ca element changed continuously for almost all the year.Differences existed among varieties,the calcium content of ‘GHsj1804’ was lower than that of ‘ GHsj1806’ and ‘GHsj1808’.(4)The contents of Mg during bud germination flowering were maintained at low levels of 400-470 mg/kg,and increased rapidly at the beginning of fruit bearing.At early stage of fruit development,the content fluctuated slightly but was maintained at a high level of 550-650 mg/kg,and rised to levels of 550 mg/kg to 600 mg/kg during the late stage of fruit development.(5)Contents of Fe elements also fluctuated considerably throughout the year.Contents of Fe decreased during bud germination and flowering.The contents of the element increased rapidly during fruit growth,and then decreased rapidly.After fruit harvested,contents of element showed a waved rising trend,and the contentsthroughout the whole year ranged between 120 to 360 mg/kg.(6)Contents of Zn decreased slightly during bud germination stage and flowering.From the early period of fruit bearing to the end of December,contents of the Zn were changed slightly,but the difference between peak and valley value was not large,and the content was within the range of 49 to 112 mg/kg throughout the year.(7)Contents of B increased and declined during bud germination and flowering,and showed a waved trend from fruit seting to the end of the year.(8)Among the 3 jackfruit varieties,significant positive correlations revealed between the elements was N-P,Zn-B and Fe-Zn,while significant negative correlation were found between N-Mg,P-Mg,Ca-B,and Ca-Zn.