The low efficiency of natural pollination in the macauba palm limits the productive potential of the species. To address this constraint, we evaluated the effectiveness of artificial interventions applied to the inflorescence and pollination process as strategies to increase fruit set following characterization of inflorescence developmental stages. Inflorescences were monitored from their emergence until natural opening. Before natural opening, physical interventions were performed to promote floral exposure, and subsequent effects on fruit set were assessed. Artificial pollination was carried out on spathes subjected to forced opening (stage IV) and on naturally opened spathes, with fruit set and fruit biometric traits quantified thereafter. Following analysis of pollen viability at stages III, IV, and V, artificial pollination was performed using pollen from both immature (stage IV) and mature (stage V) inflorescences to assess their relative fertilization efficiency. Inflorescences displayed asynchronous phenological development, with variation detected among genotypes. The physical interventions did not influence fruit set. In contrast, artificial pollination markedly enhanced fruit set without altering fruit biometric parameters, with greater gains observed in forced-opening spathes (4.6-fold increase) compared with naturally opened spathes (3.2-fold increase). Pollen collected from inflorescences at stages IV (immature) and V (mature) exhibited high viability (> 90
Range expansion and assisted establishment of tropical hardwoods under a changing climate require an understanding of early-stage mortality mechanisms. Evaluation of replicated half-sib families (HSFs) of Dalbergia latifolia across three climatically distinct locations in northern India revealed that biotic factors were the dominant mortality driver. Climatic variables did not exhibit significant independent effects after accounting for biotic stressors, suggesting that environmental conditions may influence mortality indirectly through their effects on disease and insect-pest pressure. Mortality responses varied markedly among HSFs, populations (provenances), years and locations, revealing pronounced genotype-by-environment (G×E) interactions. Notably, the Eastern India population was found to be most susceptible to disease and insect-pests severity, although populations Pop02, Pop03 (Central India), and Pop05, Pop07 (South India) exhibited higher mortality risk under biotic stress. However, populations such as Pop01 (Central India), and Pop04 and Pop06 (South India) consistently exhibited lower susceptibility and mortality across locations, suggesting underlying differences in tolerance, plasticity, and local adaptation due to their geographical proximity to the field gene banks. The locations Central University of Punjab (CUP), Bathinda (L2), and Indian Council of Forestry Research Education-Forest Research Institute (ICFRE-FRI), Dehradun (L3) amplified stress via. location-specific pressures. Collectively, these findings suggest that early establishment success in D. latifolia is shaped largely by interactions between genetic background, biotic stressors, and spatially heterogeneous environments, highlighting the importance of selecting resilient genetic material for future plantation and restoration programmes.
Cyclocarya paliurus, a multifunctional economic tree species, is sensitive to the cold stress. However, limited information is available regarding the relationship between structural carbohydrate and cold tolerance as well as the expression patterns of their biosynthetic genes under cold stress. In this study, we investigated the responses of cellulose and hemicellulose contents to cold stress in diploid and tetraploid C. paliurus seedlings, and generated a gene co-expression network to explore genes potentially linked to hemicellulose biosynthesis under simulated cold conditions. A superior cold tolerance in the diploids to the tetraploids was attributed to a higher content of cellulose and hemicellulose and less degradation under the cold stress, while the hemicellulose may play a more important role than cellulose in improving cold tolerance. Based on transcriptome analysis and sequence alignment, a total of 45 genes involved in hemicellulose biosynthesis were identified in C. paliurus, and the predominant hemicellulose compositions were glucomannan, xyloglucan and glucuronoxylan. Furthermore, 12 transcription factors potentially involved in the regulation of hemicellulose synthesis were identified through weighted gene co-expression network analysis. Three transcription factors (CpaM1st04929, CpaM1st40702 and CpaM1st20568) from diploids, and one transcription factor (CpaM1st40508) from tetraploids, exhibited significant correlations with freezing injury index. These genes serve as candidate transcription factors potentially linked to the regulation of cold tolerance. Our results not only provide the molecular basis for hemicellulose biosynthesis in C. paliurus under the cold stress but also a reference for selecting and improving the cold-resistant genotypes in other woody plant species.
Under high light, Trinitario and Forastero genotypes were susceptible to photoinhibition with Forastero genotypes exhibiting lower photosynthetic activity. Under very low light, the photosynthetic capacity of these genotypes is suboptimal. Cacao (Theobroma cacao L.) is progressively being grown using a full sun or orchard system with no shade or restricted shade. Trinitario cacao genotypes are valued for their flavour profile, however, limited work has been published on the performance of Trinitario genotypes under high light conditions. Our study examined the light response of six Trinitario genotypes (along with Upper and Lower Amazon Forastero controls) under four light conditions (20, 400, 700 and 1500 µmol m− 2 s− 1) in a greenhouse experiment. Chlorophyll fluorescence parameters were used to assess the capability of the photosystems to respond to increasing light levels. The impact of increased exposure to light on photosynthetic pigment content and the reactive oxygen species scavenging system (for SOD, CAT and APX) was also determined. Electrolyte leakage and lipid peroxidation assays were used to assess cell damage due to photoinhibition. Our findings reveal that genotypic variation was observed mostly under moderate to high light and this study suggests that the optimal light level for high photosynthetic rates in Trinitario genotypes is approximately 300–400 µmol m− 2 s− 1.
In recent decades, forest natural disturbances, such as windfall, pest outbreaks, and windthrows, became more frequent, directly or indirectly linked to climate change. These disturbances had a significant impact on the biodiversity of old-growth spruce forests in the central part of the Russian Plain, as quantitative indicators of vegetation response to environmental changes and endogenous dynamics within natural systems demonstrate. We conducted a comprehensive study at 71 permanent sample plots, which revealed that natural disturbance processes consistently and significantly altered the composition and structure of forest communities over the past 40 years. The decline of Norway spruce (Picea abies (L.) Karst.) in the main canopy layer appears to be driven by increasing winter and summer temperatures, together with a rising frequency of extreme events and biotic stresses. The primary trend we observed during this period was the growing complexity of spatial structure and the heightened heterogeneity of plant communities. While modern communities became more diverse in terms of species composition their structure became less uniform, with increased differences between dominant and rare species, heightened competition, and more pronounced dominance of individual species. These changes also affected the ecological characteristics of the communities, leading to an increase in thermal regime and a decrease in soil acidity, consistent with the overall nemoralization of the flora. Furthermore, the study established a close relationship between the morphological features of the terrain and the type of regeneration succession in structurally disturbed spruce forests.
