Trees最新文献

Key message

Application of Azotobacter vinelandii is a strategy for 'Hass' avocado at various phenological stages, showing a 25% decrease in chemical fertilizer use while improving growth and physiological performance.

Abstract

Azotobacter-based bio-stimulants increase soil nutrient availability, provide substances for plant growth, and reduce fertilizer needs. We examined drench Azotobacter vinelandii (Av) application with two chemical fertilization levels (CF: 100% and CF 75%: 75% chemical soil fertilization) on physiological, nutritional, and fruit yield parameters. Over 20 weeks, three experiments were conducted on different avocado development stages: seedlings, post-transplantation, and mature trees. In each trial, plants received soil treatments with three commercial Av doses [2.5 (Av1), 5 (Av2), and 7.5 (Av3) mL L⁻¹], with two fertilization levels. Soil Av and CF treatments were applied every 30 days from treatment start up to 16 weeks after treatment initiation (WAT). In the seedling trial, treatments with CF 75% combined with either Av2 or Av3 result in improved seedling quality, as indicated by the Dickson Quality Index (DQI), which measures 0.58 for CF 75% alone and approximately 0.79 for CF 75% with Av2 or Av3 at 20 WAT. In post-transplantation trees, CF 75% + Av2 or Av3 improved relative growth rate (0.021 and 0.024 cm cm⁻¹ week⁻¹ for CF 75% + Av2 and Av3, respectively) compared to CF 75% plants (0.013 cm cm⁻¹ week⁻¹) at 20 WAT. Mature trees showed CF 75% + Av2 or Av3 treatments had higher agronomic efficiency (44.7 and 38.2% CF 75% + Av2 and Av3, respectively) than CF 75% trees at 20 WAT. Av could serve as an alternative strategy for integrated plant nutrient management in sustainable 'Hass' avocado production as it reduces chemical fertilization needs by 25% without impacting crop physiology.

Key message

This study identified traits with high genetic variability and heritability that are strongly correlated with leaf yield and identified high-yielding genotypes suitable for use as parents in breeding programs.

Abstract

Mulberry is a crucial crop for the sericulture industry, as it is the exclusive food source for the silkworm (Bombyx mori L.). This study evaluated the yield- and yield-associated traits of 203 mulberry genotypes for two consecutive years to identify the best traits and high-yield genotypes. The analysis of variance (ANOVA) revealed significant differences (p < 0.05) among the accessions for the six studied traits. The hundred leaf weight (HLW), leaf area (LA) and number of leaves on the longest shoot (NLS) presented high phenotypic coefficients of variance (39.48, 32.9 and 22.13, respectively), high genotypic coefficients of variance (31.79, 28.11 and 20.78, respectively), high heritability (64.84, 73.00 and 88.22, respectively) and genetic advance (52.82, 49.54 and 40.27, respectively) and significant correlations (r = 0.51***, r = 0.42***, r = 0.39***, respectively), with leaf yield, indicating the potential of these traits for indirect selection for high leaf yielding genotypes in mulberry. Hierarchical cluster analysis grouped the 203 mulberry genotypes into seven clusters, which revealed significant genetic diversity among the genotypes. PCA revealed that the first two components accounted for 78.73% of the total variation. PC1 was primarily associated with leaf yield (−0.40), whereas traits such as HLW (0.54), LA (0.51), and NLS (−0.48) contributed strongly to PC2. Seven genotypes (ME-0005, ME-0246, ME-0169, MI-0523, Vishala, MI-0029, and MI-0580) presented relatively high PC1 and PC2 scores, which were associated with increased leaf yield, HLW, LA, and NLS. The results of this study are valuable in identifying the best traits and diverse and high-yield parental genotypes for use in hybridization programs.

Mangroves are specialized intertidal plants that rely on mineral and organic inclusions viz., calcium oxalate crystals (CaOx), tannin, latex, gum and starch grains. These inclusions contribute to structural support (e.g., CaOx crystals), herbivore defense (e.g., CaOx crystals, tannin, and latex), wound sealing and desiccation protection (e.g., gum), physiological resilience under high salinity and tidal stress (e.g., starch grains as osmotic regulators). CaOx crystals may not only hold functional and ecological relevance such as internal Ca homeostasis, Ca recycling, oxalate detoxification and internal carbon reservoirs but also reflect taxonomic and phylogenetic implications. However, a comprehensive anatomical characterization of such inclusions in mangroves’ wood and bark remains underexplored, particularly in relation to their systematic and phylogenetic implications. This study is the first to comprehensively document and compare CaOx crystal morphology, frequency, cellular location, dimensions and elemental composition, along with the distribution of organic inclusions (tannin, latex, gum, starch grains) within mature wood and bark of twenty mangrove taxa from the Indian Sundarbans. We correlated observed crystal morphotypes with molecular phylogenetic framework based on rRNA gene sequences of studied mangrove taxa that reveals strong genus-level consistency and taxonomic cohesion. Distinct crystal morphologies with consistent tissue-specific deposition patterns across genera, serving as supplementary markers for genus-level identification in mangrove systematics. Principal Component Analysis of relative crystal morphotype frequencies supported genus-level clustering of species, indicating taxonomic cohesion of taxa having similar crystal profiles, which is consistent with high intragenic rRNA gene sequence similarity indices, suggesting phylogenetic conservation in crystal traits within each genus. These findings link anatomical data (calcium oxalate crystal traits) and molecular phylogeny of mangroves, offering new insights into mangrove taxonomy, phylogeny and adaptive biology.

Key message

The distribution pattern of C, N, P and dry matter content in plant leaves in low subtropical forests is complex and influenced by both developmental processes and seasonal climate change.

Abstract

The functional traits of leaves are expected to be used to estimate the effects of global climate change on plant communities. However, current research only considers changes in mature leaves, and the effects of seasonal changes and developmental processes on the functional traits of leaves are often overlooked. Here, we evaluated the relationships between leaf carbon (C), nitrogen (N), phosphorus (P) and leaf dry matter content (LDMC) in 41 tree species of subtropical evergreen broad-leaved forests at seasonal scales and developmental scales. On a seasonal scale, mature leaves had significantly higher P and LDMC, with all N:P ratios > 16. However, N:P ratio of young leaves showed no significant seasonal variation, both being < 14. On developmental scale, N:P ratio and LDMC of young leaves were significantly lower than those of mature leaves, while N and P concentrations were significantly higher than those of mature leaves. In addition, C:N, C:P, N:P significantly positively correlated with LDMC in leaves, while N and P content are significantly negatively correlated with LDMC. This study illustrated that in subtropical forest plants, P limitation occurred only in mature leaves and is mitigated during dry seasons, while N limitation occurred in the young leaves. The changes from wet to dry seasons and from young to mature leaves both contributed to the increase in LDMC by affecting the element content and allocation ratio in the leaves. The study provided insights for predicting the future impact of climate change on the development of subtropical forest communities.

Key message

We introduce an approach to studying partial crown dieback that accounts for height profiles of bark thickness and stem vulnerability to fire, resulting in improved modeling of biomass loss.

Abstract

Fire mediates tree cover in savannas by causing topkill, typically represented as a binary process in which the whole stem either survives or dies, overlooking losses of foliage and branches from partial canopy dieback. To overcome this limitation, we introduce an approach that focuses on conditional probabilities of dieback of stems and branches, which we demonstrate with a Brazilian savanna tree. We quantified the probability of branch death as a function of bark thickness and height above ground, to parameterize a model of tree architecture for simulating aerial biomass losses under scenarios of differing fire intensity, maximum tree height, and investment in bark. The study population experienced a 43% loss of stem biomass when exposed to a prescribed fire, but the traditional all-or-nothing approach that ignores partial dieback accounts for only half of this loss. Simulations show that, in absolute terms, the traditional approach more substantially underestimates carbon losses in severe fires, but in relative terms, the underestimation is greater in mild fires. A benefit–cost analysis revealed that the observed investment in bark more closely matches the predicted optimal investment when we account for partial dieback. In scenarios of low fire intensity or taller tree stature, the model predicts lower investment in bark, compared to the default scenario. We introduce the concept of bark safety margin, which quantifies the relative protection afforded by bark in the main stem and branches. This study thus demonstrates the importance of considering partial stem dieback, in addition to offering a new approach for quantifying this dieback.

Bark structure in seven South African species of Ekebergia, Nymania, Trichilia and Turraea (Meliaceae) was studied to clarify the relationships between its macroscopic appearance and anatomical traits. Like other Meliaceae, these species share the subepidermal initiation of periderm, the presence of phloem fibers, and compound sieve plates. Diagnostic bark characters were revealed to identify these taxa. All studied species share stretching bark showing conspicuous expansion without regular shedding. Their continuity is maintained by anticlinal divisions of phellogen cells and by the formation of expansion cracks, i.e., the superficial disruptions associated with new portions of the periderm. The lenticels found in all studied taxa except Trichilia, unlike expansion cracks, are derived from non-disrupted periderm. The mature bark of E. capensis shows conspicuous radial expansion of secondary phloem by periclinal divisions of axial parenchyma (proliferation tissue), which has not been reported elsewhere. Reticulate fracturing of mature bark in Ekebergia and Trichilia is presumably associated with the presence of elastic parenchymatous layers covered by a rigid periderm. We hypothesize that such elastic layers can redistribute the stressing forces of radial wood increment into the tensile forces stretching the periderm parallel to the bark surface, which cracks not only vertically but also horizontally and diagonally.

Key message

Effective nature-based solutions for urban air pollution require understanding how season, site, and species affect tree tolerance. The complex interplay of biochemical parameters significantly impacts trees’ sensitivity and tolerance.

Abstract

Evaluating dominant tree species as bioindicators can provide valuable insights for effective air pollution mitigation strategies in rapidly developing cities like Ranchi, Eastern India. The air pollution tolerance index (APTI), anticipated performance index (API), and dust capturing capacity (DCC) of dominant urban street trees in Ranchi were studied at control, heavy traffic, and industrial sites during pre- and post-monsoon seasons. APTI varied significantly across seasons (F_1,25.43 = 27.24, p < 0.05), sites (F_2,261.87 = 280.50, p < 0.05), and trees (F_9,9.18 = 9.83, p < 0.05). APTI values were highest at industrial, followed by heavy traffic, and lowest at control sites. AA content was the most influential biochemical parameter associated with APTI, showing a statistically significant strong correlation (r = 0.819, p < 0.01). Street trees at industrial sites exhibited the highest APTI values (range: 15.11–19.99), followed by heavy traffic sites (12.79–18.30), and lowest at control sites (11.46–15.72). DCC also varied significantly across seasons (F_1,0.321 = 17.40, p < 0.05), sites (F_2,2.65 = 144.25, p < 0.05), and trees (F_9,2.95 = 160.92, p < 0.05). The highest DCC was recorded in Melia azedarach (2.64 mg cm⁻²), followed by Bauhinia variegata (2.49 mg cm⁻²), and Bridelia retusa (2.13 mg cm⁻²). APTI, API, and DCC were significantly affected by seasons, sites, species, and their interactions with pollutants. These findings highlight the importance of APTI, API, and DCC as important indicators of the pollution mitigation abilities of different urban street trees to recommend for urban greening initiatives in rapidly urbanizing cities like Ranchi.

Graphical Abstract

Key message

Knowledge of the efficiency of nitrogen absorption contributes to the selection of olive cultivars that are more efficient in absorbing N even at low concentrations in the environment.

Abstract

Fertilization of olive trees (Olea europaea L.) generally follows standardized nitrogen (N) doses, without considering the specific efficiency of each cultivar in N absorption. The lack of knowledge about kinetic parameters can result in excessive application, increasing environmental risks and impairing oil quality. The study aimed to characterize the most efficient olive cultivars in the absorption of N, NO₃⁻, and NH₄⁺ forms, and to determine whether kinetic, photosynthetic variables, and root morphological parameters contribute to the selection of cultivars that are more efficient in the use of N. Four olive cultivars were grown hydroponically for 21 days in nutrient solution and transferred to 0.03 mol L⁻¹ CaSO₄ solution for 15 days. Subsequently, the plants received nutrient solution again and periodic collection began during a 61-h kinetic absorption march. The cultivar Coratina was the most efficient in NO₃⁻ absorption, presenting higher V_max (maximum absorption speed) and lower K_m (Michaelis–Menten constant) and C_min (minimum concentration) values, which allows N absorption at low concentrations due to the affinity of root transporters. Its greater length, surface area, and quantity of fine roots favored this efficiency. It also presented better photosynthetic parameters and greater N accumulation in roots. Arbequina and Koroneiki had high K_m and C_min for NO₃⁻ and NH₄⁺, while Arbosana presented lower C_min values for NH₄⁺. These results show that different cultivars have distinct nutritional strategies and that physiological and morphological parameters are essential in choosing the best cultivars and optimizing nitrogen fertilization, ensuring greater sustainability and productivity in olive cultivation.