Population structure and phenological attributes of Adansonia digitata L. (baobab) in Northwestern lowland area of Ethiopia

Adansonia digitata (baobab), a multipurpose and highly valued tree species, is facing threats due to anthropogenic factors like shifting cultivation practices and fire. The aim of this study was to examine the population structure and phenological attributes of baobab in three districts (i.e. Kafta Humera, Tselemt, and Quara district) in Northwestern Ethiopia. The study was carried out by establishing 17 plots 1 km long and 100 m wide covering a total area of 170 ha in the Quara district and five plots covering 50 ha each in the Kafta Humera and Tselemt districts. Further, plots were subdivided into 25 × 25 m and 5 × 5 m sub-plots for recording other woody species and their regeneration status, respectively. Thirty reproductively matured trees with easily visible crowns were selected to record phenological characteristics and fruit yield. The findings revealed that baobab population was significantly higher in the Tselemt district (3.15 ± 0.15) as compared to Quara (1.43 ± 0.43) and Kafta Humera (1.30 ± 0.23) sites. A bell-shaped diameter distribution was observed in the Quara district and irregular-shaped distributions were observed in Kafta Humera and Tselemt districts. Phenological periodicity and fruit production of baobab did not vary significantly among the three study sites. On average, 404 fruits per tree were recorded with a maximum of 559 fruits in mid-diameter size class trees. Due to livestock browsing, shifting cultivation practices, and uncontrolled fire, the recruitments are limited in the study areas. An in-situ conservation strategy through the plantation and proper management practices are needed to sustain baobab tree species.

Fruit yield and yield-related traits of okra [Abelmoschus esculentus (L.) moench] genotypes as influenced by different seed priming techniques in Dire Dawa, Ethiopia

Okra is a commercially important vegetable crop that grows in tropical, subtropical, and warm temperate parts of the world, but its productivity is hindered by a lack of improved cultivars and delayed and erratic seedling emergence in the field. An experiment was conducted to evaluate the effect of seed priming treatments on okra genotypes' seedling emergence and fruit yield. In this experiment, Clemson spineless, Arka Anamika, SOH701, 240,207, and 240,586 okra genotypes were primed with tap water, 50% cow urine, 200 ppm GA₃, and 0.5% KH₂PO₄ as treatments, and dry seed of each genotype was used as a control. The experiment was conducted in Dire Dawa by irrigation in a randomized complete block design with three replicates. GenStat software was used to analyse all the data collected in this experiment. Genotype and seed priming treatments significantly affected phenology, growth, fruit yield, and yield-related traits, and their interactions affected the above traits, except for days to seedling emergence and fruit number per plant. Genotype Clemson spineless (5.13 days) and seed primed with GA₃ (4.6 days) had the shortest days to 50% seedling emergence, and genotype 240,586 primed with KH₂PO₄ produced the highest fruit yield per hectare (37.78 t ha^-1). So, farmers in the study area are advised to use genotype 240,586 with KH₂PO₄ seed priming to increase fruit yield. However, research conducted at one site should be repeated at multiple sites in order to make recommendations that are relevant to the country.

Assessment of the differential trade-off between growth, subsistence, and productivity of two popular Indian hybrid mango varieties under elevated ozone exposure

The multifunctionality of plants is well known to be compromised in the areas experiencing higher concentrations of tropospheric ozone (O₃). Mango (Mangifera indica L.) cultivation is essential to the economy of tropical regions, including India. Mango, widely grown in suburban and rural areas, experiences production loss due to air pollutants. Ozone, the most important phytotoxic gas in mango growing areas, warrants an investigation of its effects. Therefore, we assessed the differential sensitivity of mango saplings (two-year-old hybrid and regular-bearing mango varieties, Amrapali and Mallika) at two levels of O₃: ambient and elevated (ambient + 20 ppb) using open-top chambers from September 2020 to July 2022. Under elevated O₃, both varieties showed similar seasonal responses (winter and summer) for all the growth parameters but differed in their height-diameter allocation pattern. A decrease in stem diameter and an increase in plant height were observed in Amrapali, whereas Mallika showed a reverse response. Early emergence of phenophases was noticed during the reproductive growth of both varieties under elevated O₃ exposure. However, these changes were more pronounced in Amrapali. Stomatal conductance was more negatively affected in Amrapali than in Mallika under elevated O₃ during both seasons. Furthermore, leaf morpho-physiological traits (leaf nitrogen concentration, leaf area, leaf mass per area, and photosynthetic nitrogen use efficiency) and inflorescence parameters responded variably in both varieties under elevated O₃ stress. A decrease in photosynthetic nitrogen use efficiency, further enhanced yield loss which was more pronounced in Mallika than in Amrapali under elevated O₃ exposure. The results of this study could be useful in selecting a better-performing variety based on its productivity, which will be economically more beneficial in achieving the goal of sustainable production at the anticipated high O₃ levels under a climate change scenario.

Assessing the impact of varied nitrogen dosages on the vegetative and reproductive parameters of 'Sweet Sensation' and 'Rubygem' strawberry in Morang, Nepal

Between 2020 and 2021, an experimental investigation was conducted in Tropical conditions to assess the effects of varying levels of nitrogen fertilization (0 kgNha^-1, 0.5 kgNha^-1, 1 kgNha^-1, 1.5 kgNha^-1, and 2 kgNha^-1) on the growth and yield parameters of two strawberry cultivars (Sweet Sensation and Rubygem) in a sandy loam soil. The results demonstrated that the application of nitrogen positively influenced both vegetative (such as plant height, leaf number per plant, canopy spread, and crown diameter) and reproductive (such as number of flowers and fruits per plant, fruit yield, and TSS content) traits of both strawberry cultivars. Furthermore, the findings indicated that Sweet Sensation responded more positively to higher nitrogen doses than Rubygem in all aspects. The data showed that the utilization of 2 kgNha^-1 resulted in the highest fruit yield (0.390-0.508 t/ha) and quality traits, including TSS (7.89-9.21%). While there were no significant variations in TSS content among the plants treated with different nitrogen levels, significant differences were observed between the two strawberry cultivars.

Japanese plums behavior under water stress: impact on yield and biochemical traits

This work investigates response to drought of nine local cultivars alongside two exotic varieties of Japanese plum (Prunus salicina L.) through their yield and fruit quality components. It was carried out at Sais plain, northern Morocco, over two consecutive years (2019–2020). Water stress was imposed by a deficit irrigation (DI) treatment of 50% ETc during the whole fruit growth period, compared to full irrigation of 100% ETc (CI). At their full ripening stage, the cultivars were assessed for their yield, fruit weight and fruit quality attributes, namely total soluble solids (TSS), pH, titratable acidity (TA), maturity index (MI), soluble sugars content (SSC), amino acids content (AAC), total phenolic compounds (TPC) and total antioxidant capacity (TAC). Results displayed significant decrease in yield and fruit weight since the first year of DI application. Owing to calculated stability indexes of the aforementioned traits along with water use efficiency, the local cultivar ‘Fortu-43’ was the most insensitive to drought, whereas ‘Timhdit’ and ‘Black-D35’ showed the lowest drought tolerability. The effects of water stress on fruit chemical and biochemical traits varied significantly among cultivars, exhibiting an overall significant improvement in fruit quality. Two-dimensional clustered heatmap analysis subdivided the cultivars into two distinct clusters, mainly discriminated based on stability indexes of SSC, MI, TPC and TAC. Among the latter, SSC stability index was probably the most significant drought tolerance marker for Japanese plum.

Application of homobrassinolide enhances growth, yield and quality of tomato

Brassinosteroids (BRs) have emerged as pleiotropic phytohormone owing to their wide function in crop growth and metabolism. Homobrassinolide (HBR) being an analogue of BRs is known to improve the growth, yield and quality parameters in many crop plants. Thus, an evaluation study was conducted for two years (2018 and 2019) to elucidate the performance of tomato plants (Solanum lycopersicum L.) to a novel group of phytohormone,HBR. The field experiment comprised of seven treatments with homobrassinolide 0.04% (Emulsifiable Concentrate) EC at four different concentrations (0.06, 0.08, 0.10 and 0.12 g active ingredient (a.i.) ha⁻¹) and two well-known growth promoters viz., Gibberellic acid (GA), Naphthalene Acetic Acid (NAA) along with the untreated control. Plant height and chlorophyll concentration were found significantly different in both years of experiment as well as among the different treatments. HBR at 0.12 g a.i. ha⁻¹ was found better with maximum number of fruits (77.36 plant⁻¹), fruit length (6.72 cm), fruit breadth (6.45 cm) and fruit weight (80.52 g) over other concentrations and treatments. Fruit yield was more pronounced in the plots treated with plant growth regulators compared to untreated control. However, significantly higher fruit yield of 91.07 t ha⁻¹ (62.58 t ha⁻¹ with untreated control) along with improved quality traits viz., fruit firmness (4.11 kg cm⁻²), ascorbic acid content (24.09 mg 100 g⁻¹), total soluble solids (4.43°Brix) and keeping quality (12.50 days) was recorded in 0.12 g a.i. ha⁻¹ HBR treated plots. Thus, it can be inferred that HBRapplication would be a better option to enhance growth, yield as well as quality traits in tomato.

Effects of native pollinator communities on the physiological and chemical parameters of loquat tree (Eriobotrya japonica) under open field condition

Wild and managed pollinators are the key component of biodiversity, contributing to important ecosystem services such as pollination and supporting human food security. Pollination by insects is a crucial component of the food chain that ensures the production of fruits and strongly affects the fruit quality, but the effect of insect pollination on fruit physiological and chemical parameters is largely unknown. The current study was conducted to determine the insect pollinators diversity and their relative abundance in the loquat (Eriobotrya japonica) orchard during 2017–2019. Further, the effect of insect pollinators pollination on the physiological and chemical parameters of fruit quality as compared to control pollinated flowers was investigated. The results revealed that a total of 22 species from 3 families (Apidae, Halictidae, and Syrphidae) were identified during the flowering season. The Apidae and Syrphidae were the most frequently observed families with major groups honey bees (67.89%) and hoverflies (21.57%), respectively. Moreover, results indicated that the fruit yield by the open-pollinated flowers (22.31 ± 0.34 kg/tree) was significantly higher than the control pollinated flowers (14.80 ± 0.25 kg/tree). Physiological and chemical parameters of loquat fruit differed significantly when fruits obtained from open-pollinated flowers as compared to control pollinated flowers. These results suggested that native insect pollinators play important role in the fruit quality of loquat. Hence, maintenance of appropriate habitat of native pollinators near loquat orchards is necessary to ensure good productivity and fruit quality.

Na+ transporter HKT1;2 reduces flower Na+ content and considerably mitigates the decline in tomato fruit yields under saline conditions

Genes encoding HKT1-like Na⁺ transporters play a key role in the salinity tolerance mechanism in Arabidopsis and other plant species by retrieving Na⁺ from the xylem of different organs and tissues. In this study, we investigated the role of two HKT1;2 allelic variants in tomato salt tolerance in relation to vegetative growth and fruit yield in plants subjected to salt treatment in a commercial greenhouse under real production conditions. We used two near-isogenic lines (NILs), homozygous for either the Solanum lycopersicum (NIL17) or S. cheesmaniae (NIL14) allele, at HKT1;2 loci and their respective RNAi-Sl/ScHKT1;2 lines. The results obtained show that both ScHKT1;2- and SlHKT1;2-silenced lines display hypersensitivity to salinity associated with an altered leaf Na⁺/K⁺ ratio, thus confirming that HKT1;2 plays an important role in Na⁺ homeostasis and salinity tolerance in tomato. Both silenced lines also showed Na⁺ over-accumulation and a slight, but significant, reduction in K⁺ content in the flower tissues of salt-treated plants and consequently a higher Na⁺/K⁺ ratio as compared to the respective unsilenced lines. This altered Na⁺/K⁺ ratio in flower tissues is associated with a sharp reduction in fruit yield, measured as total fresh weight and number of fruits, in both silenced lines under salinity conditions. Our findings demonstrate that Na⁺ transporter HKT1;2 protects the flower against Na⁺ toxicity and mitigates the reduction in tomato fruit yield under salinity conditions.

Biogas digestates are not an effective nutrient solution for hydroponic tomato (Lycopersicon esculentum L.) production under a deep water culture system

The generation of energy through anaerobic digestion using animal manures is being promoted as an environmentally sustainable method of managing animal wastes. However, sustainability of biogas production is reliant on the sustainable utilization of the digestates that emanate from the process. Our study evaluated the effects of the biogas digestates on crop phytotoxicity and their fertilizer potential as a nutrient solution in hydroponic tomato production. Biogas digestates diluted up to 40% (v/v) resulted in significantly (P < 0.05) the lowest relative seed germination (RSG) in all vegetables evaluated in our study. The highest RSG was observed in the 10% biogas digestates, which was higher than the control treatment. For the crop growth study, relative to the control,the treatments with 20%, 40% and 60% mineral fertilizer substitution resulted in 39.4%; 22.8% and 8.7% significantly (P < 0.05) lower chlorophyll content, respectively. On average, the treatments with biogas slurry, though substituted with mineral fertilizers, resulted in a 275% lower fresh fruit yield compared to the control treatment. However, with biogas digestates, the sugar content in the tomato fruits significantly increased, whilst the heavy metal content was below that recommended limit when irrigation water is used. The results of our study demonstrated that cow based digestates are not a suitable nutrient media for hydroponic tomato production. Moreover, even with mineral fertilizer supplementation, only the control treatment containing only mineral hydroponic fertilizer resulted in positive growth and yield in tomatoes.

Effect of different combinations of antibiotics on fruit quality and antioxidant defense system in Huanglongbing infected Kinnow orchards

Huanglongbing (HLB), also known as citrus greening disease, is the most devastating disease of citrus across the world, caused by the phloem limited fastidious bacterium ‘Candidatus Liberibacter spp.’. This research was conducted on HLB infected 10-year-old Kinnow orchard located at Multan, Pakistan. Different classes of antibiotics in various combinations were applied on HLB-infected trees. The antibiotic treatments were applied before flowering in February, during fruit setting in April and at fruit growth stage in June. The different antibiotics combinations used were Ampicillin sodium + Rifampicin, Cefalexin + Rifampicin, Ampicillin sodium + Cefalexin, Ampicillin sodium + Cefalexin + Rifampicin and Control (distilled water). Different fruit qualitative and quantitative attributes were examined. The application of antibiotics significantly decreased 2–11% in flower, June and pre-harvest drops as compared to control. Further, antibiotics increased fruit weight and yield by five times while the juice content, total soluble solids, ripening index, total sugars, phenolic and vitamin C content were also increased in fruits. In addition, total soluble proteins, peroxidase and catalase activities were increased in fruits harvested from antibiotic treated plants compared to control, however the superoxidase dismutase activity was decreased in fruits of antibiotic treated plants. Finally, it is concluded that application of different antibiotics combinations helps in improving the fruit yield and different quality attributes of HLB infected Kinnow trees.

Construction of an ultrahigh-density genetic linkage map for Jatropha curcas L. and identification of QTL for fruit yield

BACKGROUND

As an important biofuel plant, the demand for higher yield Jatropha curcas L. is rapidly increasing. However, genetic analysis of Jatropha and molecular breeding for higher yield have been hampered by the limited number of molecular markers available.

RESULTS

An ultrahigh-density linkage map for a Jatropha mapping population of 153 individuals was constructed and covered 1380.58 cM of the Jatropha genome, with average marker density of 0.403 cM. The genetic linkage map consisted of 3422 SNP and indel markers, which clustered into 11 linkage groups. With this map, 13 repeatable QTLs (reQTLs) for fruit yield traits were identified. Ten reQTLs, qNF-1, qNF-2a, qNF-2b, qNF-2c, qNF-3, qNF-4, qNF-6, qNF-7a, qNF-7b and qNF-8, that control the number of fruits (NF) mapped to LGs 1, 2, 3, 4, 6, 7 and 8, whereas three reQTLs, qTWF-1, qTWF-2 and qTWF-3, that control the total weight of fruits (TWF) mapped to LGs 1, 2 and 3, respectively. It is interesting that there are two candidate critical genes, which may regulate Jatropha fruit yield. We also identified three pleiotropic reQTL pairs associated with both the NF and TWF traits.

CONCLUSION

This study is the first to report an ultrahigh-density Jatropha genetic linkage map construction, and the markers used in this study showed great potential for QTL mapping. Thirteen fruit-yield reQTLs and two important candidate genes were identified based on this linkage map. This genetic linkage map will be a useful tool for the localization of other economically important QTLs and candidate genes for Jatropha.

Improving agronomic water use efficiency in tomato by rootstock-mediated hormonal regulation of leaf biomass

Water availability is the most important factor limiting food production, thus developing new scientific strategies to allow crops to more efficiently use water could be crucial in a world with a growing population. Tomato is a highly water consuming crop and improving its water use efficiency (WUE) implies positive economic and environmental effects. This work aimed to study and exploit root-derived hormonal traits to improve WUE in tomato by grafting on selected rootstocks. Firstly, root-related hormonal parameters associated to WUE were identified in a population of recombinant inbred lines (RILs) derived from the wild tomato species Solanum pimpinellifolium. A principal component analysis (PCA) revealed that some hormonal traits were associated with productivity (plant biomass and photosynthesis) and WUE in the RIL population. Leaf ABA concentration was associated to the first component (PC1) of the PCA, which explained a 60% of the variance in WUE, while the ethylene precursor ACC and the ratio ACC/ABA were also associated to PC1 but in the opposite direction. Secondly, we selected RILs according to their extreme biomass (high, B, low, b) and water use (high, W, low, w), and studied the differential effect of shoot and root on WUE by reciprocal grafting. In absence of any imposed stress, there were no rootstock effects on vegetative shoot growth and water relations. Finally, we exploited the previously identified root-related hormonal traits by grafting a commercial tomato variety onto the selected RILs to improve WUE. Interestingly, rootstocks that induced low biomass and water use, 'bw', improved fruit yield and WUE (defined as fruit yield/water use) by up to 40% compared to self-grafted plants. Although other hormonal factors appear implicated in this response, xylem ACC concentration seems an important root-derived trait that inhibits leaf growth but does not limit fruit yield. Thus tomato WUE can be improved exploiting rootstock-derived hormonal signals which control leaf growth.

The effect of choline-stabilized orthosilicic acid on microelements and silicon concentration, photosynthesis activity and yield of tomato grown under Mn stress

The aim of experiments was to assess the efficiency of choline-stabilized orthosilicic acid (ch-OSA; complex of orthosilicic acid with choline and a bioavailable source of silicon) application under increasing manganese (Mn) stress on the micronutritional composition and yielding of tomato (Solanum lycopersicum L. cvs. 'Alboney F1' and 'Emotion F1'). Plants were grown in rockwool with the application of a nutrient solution varied the Mn concentrations (in mg dm(-3)): 9.6 and 19.2 which cause strong oxidative stress of plants comparing with optimal concentration of that microelement in nutrient solution. The effect of ch-OSA application (at Si concentration of 0.3 mg dm(-3) nutrient solution) was investigated at both Mn-levels. Increasing Mn stress modified the concentration of microelements and silicon (Si) in tomato leaves. Application of ch-OSA also influenced the concentration of nutrients, but the determined changes were generally multidirectional and varied depending on Mn-level and cultivar. Under the increasing Mn stress a significant downward trend was observed for the mean concentration of Fe (in both cultivars) in fruits--but changes of Mn, Zn and Cu were varied depend on cultivar. In the case of cv. 'Alboney F1' ch-OSA application caused an increase the mean concentrations of Fe, Zn and Cu, while in the case of cv. 'Emotion F1' the reduction of mean concentrations of Zn and Cu was recorded. Ch-OSA treatment did not influence on the Mn concentrations in fruits. A beneficial role of ch-OSA was also found in photosynthesis activity. This was especially valid for lower levels of Mn. Application of ch-OSA improved significantly the marketable yield of tomato under stress by a low Mn level.

Bioactive and yield potential of jelly palms (Butia odorata Barb. Rodr.)

In this descriptive study, Butia odorata genotypes were evaluated for yield, fruit number, pulp yield, bioactive content (including phenolic compounds, carotenoid, anthocyanin, L-ascorbic acid, and fibre content), antioxidant potential, and phenotypic characteristics. Genotype 117 was the highest yielding, with an estimated fruit yield of 22,000 kg ha(-1) and pulp yield of 12,000 kg ha(-1). On the other hand, the lowest yielding genotype, accession 49, showed an estimated fruit yield of 8400 kg ha(-1). Jelly palm fruit were generally rich in phenolic content (280.50-398.50 mg 100(-1)g), carotenoid content (2.80-4.08 mg 100 g(-1)), and L-ascorbic acid content (34.63-63.84 mg 100g(-1)). While the highest yielding genotype was not the richest in bioactive content, the lowest yielding genotype showed the highest l-ascorbic acid content. Although fruit yield and phytochemical composition are desirable attributes in jelly palm fruit, none of the genotypes evaluated showed high levels of both. Therefore, fruit yield and bioactive phytochemical content appear to be inversely proportional.