A field study was carried out to evaluate the relationship between the infestation rate by Parlatoria oleae on the
measurements of vegetative growth and nutritional status in seedy Balady mango leaves at Esna district, Luxor Governorate
through the two consecutive seasons from the beginning of September, 2016 until mid-August, 2018. The two seasons data
indicated that, the uninfested mango leaves had better vegetative growth measurements (shoot length, shoot thickness,
number of leaves per shoot, leaf area and leaf index), physical properties (fresh weight, weight after one hour of drying in
air, moisture and specific leaf area) and chemical properties (N, P, Mg, Zn, Fe, Mn and Cu) and crude protein content in
mango leaves than those of the light and heavily infested leaves. While, in contrast, the dry weight, dry matter, loss moisture
content and specific leaf weight, in addition to K and Ca contents increased significantly in the infested leaves as compared
to the uninfested leaves. The two latter elements (K and Ca) may play a role in the defense mechanism of mango leaves
against sap-sucking pests infestation. Also, the heavily infested leaves were considered the greatest infestation by pest and
exhibiting the highest reduction in all studied measurements, except exposing the highest increasing in (dry weight, dry
matter, loss in moisture content, specific leaf weight and K and Ca elements) than the lower rates of infestation (free and
light). Generally, it seems that the population density of P. oleae during autumn months was the highest causing the greatest
loss in studied measurements in autumn growth cycle of mango trees during the two seasons as compared with other growth
cycles. The loss in the measured parameters was a summation of many factors including the rate of infestation, time of
infestation, element contents, essential nutrients and the plant variety. |
