![]() The twig cross-sectional area was significantly positively correlated with individual leaf area, total leaf area and total leaf dry mass, but was significantly negatively correlated with volume-based leafing intensity, among them, the cross-sectional area of small trees and large tree has an isokinetic growth relationship with the total leaf area and total leaf dry mass close to 1, while the medium tree has an allometric growth relationship close to 1.5 individual leaf area exhibited significant negative correlations with volume-based leafing intensity, showing an allometric relationship The diameter class has a significant effect on the slope or intercept of the correlation relationship between twig-leaf traits. Results With the increase of diameter class, twig cross-sectional area showed an upward trend, individual leaf area and total leaf area showed a downward trend, but there was no significant difference in total leaf dry mass, twig dry mass, volume-based leafing intensity. The method of Standardized main axis estimation was used to test whether the diameter class had an effect on the correlation between the twig and leaf traits. One-way analysis of variance (ANOVA) was used to test whether there were significant differences in twig-leaf traits among different diameter classes. The twig cross-sectional area, individual leaf area, total leaf area, total leaf dry mass, twig dry mass and volume-based leafing intensity were measured in different diameter classes. Methods In Liangshui National Nature Reserve of Heilongjiang Province, three diameter classes of Betula platyphylla were selected (including small tree, middle tree and large tree). Exploring the variation and correlation between twig and leaf traits of plants with different diameter classes is of great significance for understanding the intraspecific variation of plant functional traits and the resource acquisition strategies of plants. sphaerica on mango in Egypt, which might severely affect the local production of mango.Objectives Plants can use resources more efficiently by adjusting their own traits. ![]() To the best of our knowledge, this is the first report of twig dieback and leaf spot caused by N. The same fungus was re-isolated and re-identified. After 40/15 days of incubation at 24 ☌ in moist chambers, only inoculated plants/leaves had similar symptoms to those observed on affected trees. Control plants/leaves were inoculated with sterile PDA plugs. Meantime, 30 detached, surface-sterilized leaves were wounded and inoculated with a 0.5 cm-mycelial plug. To fulfill Koch’s postulates, 10-month-old mango seedlings were inoculated with a 0.5 cm-mycelial plug at the growing tip region of the stem. Sequences were deposited in GenBank (ITS, MW704467 TEF1-α, ON428976) and proved to 99.6 and 91.4% match in BLAST searches with N. Identity of EGYARC1 was confirmed by sequencing portions of rDNA-ITS region and TEF1-α gene (White et al. sphaerica EGYARC1 produced single celled, black, spherical to sub-spherical conidia, 10 to 14 × 18 to 20 μm, borne on a hyaline vesicle at the tip of conidiophore. The isolated fungus (70% frequency) was identified as Nigrospora sphaerica (Sacc.) Mason (Wright et al. Twenty leaves and wood portions from 20 diseased trees were surface sterilized in 1% sodium hypochlorite for 2 min, placed onto potato dextrose agar (PDA) and incubated in dark at 24 ☌. Dieback was characterized by the discoloration of wood and downward drying out of the twigs. Spots appeared yellow to brown, with dry grey necrotic centers, irregularly distributed on leaves. Three different locations were inspected (20 farms/location), with an incidence in the affected sites of 100%. Ewais trees cultivated in El Sharkia governorate, Egypt. ![]() During 2021, twig dieback and leaf spots were observed on mango cv. ![]()
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