Fruit Set Research Articles

Selection favours high spread and asymmetry of flower opening dates within plant individuals

Abstract Natural selection on traits expressed repeatedly by individuals is usually investigated with a focus on mean values, although within‐individual trait distributions often differ also in other aspects, such as their spread and shape. In plants producing multiple flowers during a season, there might not be a single optimal flowering time, but rather an optimal distribution of flower opening dates. This optimal distribution might depend on both resource allocation patterns and interactions with the abiotic and biotic environment. In this study, we quantified mean, variance, skewness and kurtosis of 495 individual flowering schedules (5287 flowers) over 3 years, and assessed phenotypic selection on these aspects of the within‐individual distribution of opening dates in the perennial herb Lathyrus vernus. We also explored how selection on within‐individual variation in flowering schedules was related to effects on two fitness components: fruit set and the proportion of seeds escaping pre‐dispersal predation. Within‐individual variation in phenology was larger than, or at least similar to, among‐individual variation in all years. We found phenotypic selection on several aspects of individual flowering schedules. In 1 year, selection favoured plants with higher variance in opening dates, and this coincided with a higher fruit set in plants with an increased spread of the flowering schedule. In two of the study years, selection favoured a higher asymmetry of the flowering schedule, and plants with more right‐skewed distributions had higher fruit set and higher proportions of seeds escaping predation. Both fruit set and seed predation increased with an earlier mean flowering, resulting in no net selection on mean flowering date. Synthesis: Our results suggest that phenotypic selection on the spread and shape of flower opening date distributions might be at least as important as selection on the mean flowering date. In a broad sense, this implies that we should consider the entire trait distribution if we aim to understand the evolution of traits that are expressed multiple times within individuals.

Quality evaluation of “Gấc” arils and peels according to the maturity and ripeness stages

Two parts (arils and peel) of “Gấc” fruit (Momordica cochinchinensis Spreng) were analyzed for their physicochemical properties from the stage when the fruit reached maturity to the next ripening stages. Understanding these characteristics can help identify maturity indicators and use them most effectively. Research results show that “Gấc” fruit reaches maturity at the 7th week (A1) after fruit set (WAFS). At this time, the diameter and weight of the fruit no longer increase. Subsequent changes represent a gradual color change from completely blue (A1) to completely red (A5) and dark red (A6), through three intermediate stages (from A2 to A4). “Gấc” peel synthesizes the highest lycopene content (131.72 µg/g) at stage A5 (11 WAFS) and the highest β-carotene content at both stages A4 and A5 (10 and 11 WAFS) compared to fruit at stage A1 (7 WAFS). Meanwhile, lycopene and β-carotene in arils reached the highest concentrations (1672.04±9.1 μg/g and 582.45±3.4 μg/g, respectively) at stage A5 (11 WAFS). The total polyphenol content (TPC) in “Gấc” fruit arils/peel and total chlorophyll in “Gấc” fruit peel gradually decrease through the ripening stages, the highest value was achieved when the fruit was mature (A1) and the lowest value in fully ripened fruit (A5). Although showing a decrease, “Gấc” fruit still maintained TPC content in arils and peels of 89% and 73%, respectively (stages A4 and A5). The antioxidant activity of both “Gấc” fruit arils and peel also showed similar activity. In addition, “Gấc” arils also contain the highest vitamin C content in the fully ripe fruit stage compared to other stages. Thus, harvesting “Gấc” fruit at stages A4 and A5 will have beneficial ingredients (lycopene, β-carotene, total polyphenol content and vitamin C) that are good for human health.

Assessment of Cassava Pollen Viability and Ovule Fertilizability under Red-Light, 6-Benzyl Adenine, and Silver Thiosulphate Treatments.

Understanding pollen and ovule fertility as factors influencing fruit and seed set is important in cassava breeding. Extended daylength with red light (RL) and plant growth regulators (PGRs) have been used to induce flowering and fruit set in cassava without any reference to effects on pollen viability or ovule fertilizability. This study investigated the effects of field-applied RL and PGR on pollen viability and ovule fertilizability. Panels of cassava genotypes with early or moderate flowering responses were used. RL was administered from dusk to dawn. Two PGRs, 6-benzyl adenine (BA), a cytokinin and silver thiosulphate (STS), an anti-ethylene, were applied. Pollen viability was assessed based on pollen grain diameter, in vitro stainability, in vivo germinability, ovule fertilizability, and ploidy level. Treating flowers with RL increased the pollen diameter from 145.6 in control to 148.5 µm in RL, 78.5 to 93.0% in stainability, and 52.0 to 56.9% in ovule fertilizability in treated female flowers. The fruit set also increased from 51.5 in control to 71.8% in RL-treated female flowers. The seed set followed a similar trend. The ploidy level of pollen from RL-treated flowers increased slightly and was positively correlated with pollen diameter (R2 = 0.09 *), ovule fertilization (R2 = 0.20 *), fruit set (R2 = 0.59 *), and seed set (R2 = 0.60 *). Treating flowers with PGR did not affect pollen diameter but increased stainability from 78.5% in control to 82.1%, ovule fertilizability from 42.9 to 64.9%, and fruit set from 23.2 to 51.9% in PGR-treated female flowers. Combined BA + STS application caused the highest ovule fertilizability, fruit, and seed set efficiency. These results show that RL and PGR treatments increase pollen viability and ovule fertilizability. This is important for planning pollination strategies in cassava breeding programmes.

Improving Fruit Set, Yield and Fruit Quality of Barhee Date Palms Using Some Natural Plant Extracts

This experiment was conducted during two successive seasons (2020 and 2021). The aim of this research is to study the effect of spraying Barhee date palm with some natural plant extracts on fruit set, yield and fruit physical and chemical properties. Inflorescences were sprayed with moringa and garlic extracts at 2 or 4% for both, three times (one hour before pollination, one month after pollination and two months after pollination). The obtained results indicated that spraying date palm inflorescences with moringa and garlic extracts produced higher initial fruit set as compared with the untreated ones in the two seasons. While all tested treatments improved fruit physical characteristics such as fruit weight, flesh weight, fruit length and diameter compared to the control treatment in the two studied seasons; moringa extract recorded the heaviest bunches and yield/palm in both seasons. In addition, the results showed that moringa extract at 4% increased total soluble solids%, total sugars%, reducing and non-reducing sugars% in both seasons compared to the control. Meanwhile, the lowest fruit set, bunch weight, yield/palm and fruit physical and chemical properties were recorded due to the control in both seasons. Also, all treatments reduced significantly total acidity% in both seasons. In addition, spraying moringa extract at 4% improved leaf mineral content (N, P, K, Ca and Mg) and gave the highest values followed by moringa extract at 2%, then garlic extract at 4% and 2%, respectively in both seasons.

The RNA-seq and BSA-seq analysis reveals genes associated to the control of early fruiting in walnut (Juglans regia L.)

Walnut is an important nut worldwide. The duration of the juvenile phase has a considerable impact on walnut yield. Floral transition is critical for walnut flowering and fruit setting. To improve walnut breeding, it is critical to study the mechanisms of early blooming and fruiting in early-fruiting (EF) walnuts and shorten their juvenile stages. This work used EF and later-fruiting (LF) walnuts to screen for genes associated with walnut early fruiting using RNA sequencing (RNA-seq) and bulk segregant analysis sequencing (BSA-seq). Thirty-seven key differential genes were analyzed using weighted gene co-expression network association (WGCNA) in RNA-seq, and FT, CAL, FUL, and APRR9 genes were found to be able to shorten the juvenile phase of plants by affecting the floral transition process and influencing plant fruiting time. BSA-seq was utilized to identify 3305656 SNPs and 596640 InDels in EF walnut and 925347 SNPs and 514751 InDels in LF walnut. A combined analysis of RNA-seq and BSA-seq revealed 49 structurally varied DEGs in both kinds, with 47 genes in the NC_049914.1 region, one gene in NC_049901.1, one gene locus in NC_049908.1, and eight structurally variant DEGs found solely in early fruiting walnuts. The analysis of candidate genes and verification of RT-qPCR expression revealed that JrLOC109015871 (JrPBL12), JrLOC108983551 (WRI1-like), JrLOC109016788 (WRKY12), and AP2-like genes are likely to be related to early fruiting of walnut, with WRKY12 being expressed at the highest level during the flowering peak of early fruiting walnut. It is likely that the WRKY12 gene regulates the flowering transition of walnut through the ageing pathway, allowing walnut to complete the transition from nutrient growth to reproductive growth more quickly and realize early fruiting to increase walnut yield, laying the groundwork for the study of the molecular mechanism of walnut's early fruiting trait.

Comparative Proteomic Analysis of Floral Buds before and after Opening in Walnut (Juglans regia L.).

The walnut (Juglans regia L.) is a typical and an economically important tree species for nut production with heterodichogamy. The absence of female and male flowering periods seriously affects both the pollination and fruit setting rates of walnuts, thereby affecting the yield and quality. Therefore, studying the characteristics and processes of flower bud differentiation helps in gaining a deeper understanding of the regularity of the mechanism of heterodichogamy in walnuts. In this study, a total of 3540 proteins were detected in walnut and 885 unique differentially expressed proteins (DEPs) were identified using the isobaric tags for the relative and absolute quantitation (iTRAQ)-labeling method. Among all DEPs, 12 common proteins were detected in all four of the obtained contrasts. GO and KEGG analyses of 12 common DEPs showed that their functions are distributed in the cytoplasm metabolic pathways, photosynthesis, glyoxylate and dicarboxylate metabolism, and the biosynthesis of secondary metabolites, which are involved in energy production and conversion, synthesis, and the breakdown of proteomes. In addition, a function analysis was performed, whereby the DEPs were classified as involved in photosynthesis, morphogenesis, metabolism, or the stress response. A total of eight proteins were identified as associated with the morphogenesis of stamen development, such as stamen-specific protein FIL1-like (XP_018830780.1), putative leucine-rich repeat receptor-like serine/threonine-protein kinase At2g24130 (XP_018822513.1), cytochrome P450 704B1-like isoform X2 (XP_018845266.1), ervatamin-B-like (XP_018824181.1), probable glucan endo-1,3-beta-glucosidase A6 (XP_018844051.1), pathogenesis-related protein 5-like (XP_018835774.1), GDSL esterase/lipase At5g22810-like (XP_018833146.1), and fatty acyl-CoA reductase 2 (XP_018848853.1). Our results predict several crucial proteins and deepen the understanding of the biochemical mechanism that regulates the formation of male and female flower buds in walnuts.

Phenotypic and Gene Expression Analysis of Fruit Development of ‘Rojo Brillante’ and ‘Fuyu’ Persimmon (Diospyros kaki L.) Cultivars in Two Different Locations

Fruit development and maturation rely on intrinsic genetic programs involving hormone biosynthesis and signalling and environmental cues, integrating phenological cycles and climatic issues encompassing abiotic stresses and climate change. In persimmon trees, environmental inputs strongly influence fitness and agricultural performance, and fruit yield can be severely compromised by them. We have grown two persimmon accessions (‘Rojo Brillante’ and ‘Fuyu’) under contrasting meteorological conditions of two locations in Spain and Japan. Fruit size, colour change, and firmness parameters were followed during fruit development from 30 days after fruit set until commercial ripening, and the expression of genes related to ethylene production and signalling, gibberellin response, carotenoid biosynthesis, cell wall dynamics, and oxidative stress were reported. Genes depending on intrinsic developmental programs (ethylene and ripening variables, mostly) showed common expression trends in both cultivars and locations, whereas gibberellin and abiotic stress-related genes mimicked reduced fruit growth and abiotic stress associated with higher summer temperatures (>35 °C) and lower rainfall reported in the Spanish location. The expression pattern of these genes is consistent with a growth–defence trade-off that explains fruit differential growth through hormonal and stress tolerance mechanisms.

Responses of Nutritional Status and Productivity of Timor Mango Trees to Foliar Spray of Conventional and/or Nano Zinc

The management of mango orchards is beset with a number of issues, including micronutrient deficits and significant fruit drop, which both contribute to decreases in mango tree output. Among these micronutrients, zinc is vital for increasing agricultural productivity, ensuring crop sustainability, and improving plant nutritional status during the growing season. To overcome zinc (Zn) deficiencies, this study was carried out during two successive seasons in an expected “Off” year (2022) and an expected “On” year (2023) on mature mango trees cv. Timor. To ameliorate this Zn deficiency, the effect of zinc in three forms—zinc oxide nanoparticles (ZnO NPs), sulfate (ZnSO4), and chelated (Zn-chelated)—as a foliar sprayon leaves’ mineral, chlorophyll, total carotenoids, and total carbohydrate contents and productivity were studied. Ten spray treatments were used in this study, including nano zinc (100 ppm), zinc sulfate (0.1%), and chelated zinc (0.2%) on two occasions, 7 January and 4 weeks after the first application, either alone or in combination with each other as compared to the control. In both study seasons, the results showed that all the zinc forms in mineral, chelated, or nano form had a positive effect on the number of flowers per panicle, the percentage of fruit set, the number of fruits per panicle, and the number of fruits per tree, and it decreased the percentage of fruit drop. Furthermore, all zinc forms significantly increased the leaf N, P, K, Ca, Mg, Cu, Fe, Mn, B, and Zn contents (%), and all the treatments improved the chlorophyll, total carotenoid, and total carbohydrate contents compared with the other treatments. The most effective treatment was two applications of nano zinc at 100 ppm in terms of the nutritional status and productivity of Timor mango trees.

VlMYB4 and VlCDF3 co-targeted the VlLOG11 promoter to regulate fruit setting in grape (Vitis vinifera L).

The VlLOG11 mediates the cytokinin signaling pathway to regulate grape fruit setting. Fruit set, as an accepted agronomic trait, is inextricably linked with fruit quality and yield. Previous studies have demonstrated that exogenous treatment with the synthetic cytokinin analog, forchlorfenuron (CPPU), significantly enhances fruit set. In this study, a significant reduction in endogenous cytokinins was found by measuring the content of cytokinins in young grape berries after CPPU treatment. LONELY GUYs (VlLOGs), a key cytokinin-activating enzyme working in the biosynthesis pathway of cytokinins, exhibited differential expression. Some differentially expressed VlLOGs genes were presented by RNA seq data and their functions and regulation patterns were further investigated. The results showed that VlLOG11 was differentially expressed in young grape berries after CPPU treatment. Overexpression of VlLOG11 in tomato increases the amount of fruit set, and upregulated the expression of genes associated with cytokinin signaling including SlHK4, SlHK5, SlHP3, SlHP4, SlPHP1, SlPHP2. VlMYB4 and VlCDF3 could regulate the expression of VlLOG11 by directly binding to its promoter in young grape berries during fruit set. These results strongly demonstrated that VlMYB4/VlCDF3-VlLOG11 regulatory module plays a key role in the process of fruit setting in grape. This provided a basis for the molecular mechanism of VlLOG11-mediated cytokinin biosynthesis in young grape fruit set.

Bee pollination in the shadows: The role of pseudopollen and agamospermy in the mycoheterotrophic orchid Gastrodia elata

Societal Impact StatementThe family Orchidaceae is renowned for its reliance on specialized pollinators and mycorrhizal symbioses. This study examined how the nonphotosynthetic orchid Gastrodia elata thrives on the dim forest floor, focusing on its pollination biology, particularly the chemical properties of pseudopollen and reproductive assurance mechanisms. It was found that G. elata mainly relies on Lasioglossum bees, attracted by its starch‐rich pseudopollen. Additionally, G. elata in the studied population can produce fruit through agamospermy (seeds from unfertilized ovules). Overall, the findings reveal that G. elata relies on fungi for nutrition and employs reproductive strategies such as mimicking pollen to attract bees and resorting to asexual reproduction when pollinators are scarce.Summary Mycoheterotrophy is an adaptation that allows survival in environments with low irradiance and minimal competition from autotrophic plants. However, such environments can negatively impact bee pollination, as most bees prefer open habitats. Despite this, the mycoheterotrophic orchid Gastrodia elata is known to rely on Lasioglossum bees for pollination. We investigated the reproductive biology of G. elata to understand how it overcomes pollinator limitation. Our research focused on the chemical composition and anatomical basis of G. elata pseudopollen (a substance that mimics pollen and may facilitate pollination), based on micromorphological and nutritional analyses, as well as observations of pollinator behavior. Additionally, we explored the potential presence of autogamy or agamospermy as mechanisms for reproductive assurance. The pseudopollen in G. elata originates from the disintegration of the adaxial parenchymatous tissue of the callus and is rich in starch. This contrasts with pseudopollen in most orchids, which typically originates from lip hairs and whose potential attractant is protein. Lasioglossum bees pollinating G. elata visit multiple flowers and actively collect pseudopollen. Furthermore, agamospermy serves as a reproductive safeguard in shaded habitats where insect‐mediated pollination is infrequent, at least in the investigated population. Our findings suggest that Gastrodia elata pseudopollen plays an important role in enhancing insect‐mediated pollination, particularly in relatively open habitats, while agamospermy ensures fruit set in shaded environments of the investigated population. Both pseudopollen production and agamospermy likely help overcome the pollination constraints posed by the mycoheterotrophic lifestyle.

Wild native insects are efficient pollinators of mangoes in the Northern Territory of Australia

Mango is an economically important fruit crop in tropical regions, including parts of Australia. However, the contribution of native flower visitors to mango pollination and fruit set is currently understudied. We studied cv. Kensington Pride (KP) in the Northern Territory (NT) of Australia to assess the overall contribution of insect pollinators to fruit set through pollinator exclusion treatments – open pollination, total pollinator exclusion and large pollinator exclusion (>5 mm). We also compared diurnal patterns in insect visitation with mango phenology and determined the pollination effectiveness and efficiency of flower visitors based on visitation rates, foraging behaviour and pollen deposition. At 45 days after the first pollinator survey, the number of fruits per panicle in open and large pollinator exclusion treatments was not significantly different from one another, despite large pollinator exclusion panicles receiving less than half of the number of insect visitations. Furthermore, open and large pollinator exclusion treatments had 28- and 30-times higher numbers of fruits per panicle than the total pollinator exclusion treatment, respectively, showing the importance of insect pollination. The native stingless bee Tetragonula mellipes was the most frequent visitor (7906 visits, 62.7 %), followed by a hover fly Mesembrius bengalensis (2404 visits, 19.1 %). Tetragonula mellipes had the highest mango pollen loads on their bodies and deposited more pollen grains on stigmas per visit than other flower visitors, and contributed 75.5 % to the mango pollination services, about 4.5 times more than the next most important pollinator (M. bengalensis: 16.8 %). Our results suggest that T. mellipes efficiently pollinate mango flowers in the NT when wild colonies are abundant in the native vegetation adjacent to the crop. Placing T. mellipes hives in the centre of larger mango orchards may increase pollination services and potentially farm productivity by ensuring good pollination towards the centre of orchard blocks.

Arbosana Olive Is Self-Incompatible, but Inter-Compatible with Some Other Low-Vigor Olive Cultivars

Trendy high-density olive fields are often monovarietal orchards, mostly using the cultivar Arbequina. However, Arbequina shows a strong self-incompatibility response, and its yields depend on wind cross-pollination, which is not always available. With the aim of finding suitable self-compatible cultivars that can replace Arbequina, we evaluated pollen–pistil interaction, fruit set and seed paternity in Arbosana under different pollination treatments: self-pollination, open-pollination and three cross-pollination treatments: × Arbequina, × Sikitita and × Koroneiki. All these cultivars are low-vigor cultivars suitable for high-density orchards, making them potential pollinizers for Arbosana. The results show that Arbosana is also self-incompatible with a strong reduction in fruit set due to a lower fertilization level caused by a strong inhibition of pollen tube growth in self-pollinated flowers. Seed-paternity analyses confirmed the self-incompatibility response of Arbosana and suggest that some fruit obtained in bagged shoots under self-pollination were, in fact, a product of cross-fertilization. In conclusion, we recommend against the use of Arbosana in large monovarietal orchards. On the contrary, good results were obtained under cross-pollination with Sikitita, Arbequina and Koroneiki pollen, allowing us to recommend them as pollinizers for Arbosana in appropriate pollination designs. This is the first time Arbosana self-incompatibility has been reported.

Dynamic temporal transcriptome analysis reveals grape VlMYB59-VlCKX4 regulatory module controls fruit set.

Fruit set is a key stage in determining yield potential and guaranteeing quality formation and regulation. N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) has been widely applied in grape production, the most iconic of which is the promotion of grape fruit set. However, current studies still lack the molecular mechanism of CPPU-induced grape fruit set. Here, the dynamic, high-resolution stage-specific transcriptome profiles were generated based on two different treatments and five developmental periods during fruit set in 'Kyoho' grape (Vitis vinifera L. × V. labrusca L.). Pairwise comparison and functional category analysis showed that phytohormone action cytokinin was significantly enriched during the CPPU-induced grape fruit set, but not the natural one. Value differentially expressed gene (VDEG) was a newly proposed analysis strategy for mining genes related to the grape fruit set. Notably, the cytokinin metabolic process was significantly enriched among up-regulated VDEGs. Of importance, a key VDEG VlCKX4 related to the cytokinin metabolic process was identified as related to the grape fruit set. Overexpression of VlCKX4 gene promoted the Arabidopsis plants that produce more and heavier siliques. The transcription factor VlMYB59 directly bound to the promoter of VlCKX4 and activated its expression. Moreover, overexpression of VlMYB59 gene also promoted the Arabidopsis fruit set. Overall, VlMYB59 responded to CPPU treatment and directly activated the expression of VlCKX4, thus promoting the fruit set. A regulatory pathway of the VlMYB59-VlCKX4 module in the fruit set was uncovered, which provides important insights into the molecular mechanisms of the fruit set and good genetic resources for high fruit set rate breeding.

Interplay between drought and plant viruses co-infecting melon plants

Drought affects crops directly, and indirectly by affecting the activity of insect pests and the transmitted pathogens. Here, we established an experiment with well-watered or water-stressed melon plants, later single infected with either cucumber mosaic virus (CMV: non-persistent), or cucurbit aphid-borne yellow virus (CABYV: persistent), or both CMV and CABYV, and mock-inoculated control. We tested whether i) the relation between CMV and CABYV is additive, and ii) the relationship between water stress and virus infection is antagonistic, i.e., water stress primes plants for enhanced tolerance to virus infection. Water stress increased leaf greenness and temperature, and reduced leaf water potential, shoot biomass, stem dimensions, rate of flowering, CABYV symptom severity, and marketable fruit yield. Virus infection reduced leaf water potential transiently in single infected plants and persistently until harvest in double-infected plants. Double-virus infection caused the largest and synergistic reduction of marketable fruit yield. The relationship between water regime and virus treatment was additive in 12 out of 15 traits at harvest, with interactions for leaf water content, leaf:stem ratio, and fruit set. We conclude that both virus-virus relations in double infection and virus-drought relations cannot be generalized because they vary with virus, trait, and plant ontogeny.

Crops dependency on pollinators to secure pollination success and fruit development: A case study of almond varieties from Morocco

AbstractThe contribution of insects to pollination constitutes a globally important ecosystem service. Due to the increasing demand for entomophilous crops, the nutritional and economic importance of insect‐pollinated crops and the inability of managed pollinators (Apis mellifera L) to meet the high demand for their services indicate that agriculture heavily relies on wild pollinators. Almonds are an economically valuable crop in Morocco. Therefore, it is essential to understand the fundamental pollination requirements of major almond varieties to promote their production. The main objectives of this study were to assess the dependency of three almond cultivars (Espoir, Largueta and Planeta) on insect pollination, and then to evaluate the pollination deficit resulting from the lack of these pollinators. For this purpose, we used insect‐proof net bags constructed around branches of almond trees to compare fruit set and yield with open and open + hand‐pollinated flowers. The results of the fruit set experiment confirmed that all three varieties require insect pollination, as fruit set and yield were significantly higher in insect‐pollinated than insect‐isolated trees. All three almond varieties were categorized as obligatory dependent on biotic pollinators. In addition, two out of the three studied almond varieties showed high pollination deficit resulting from the lower abundance and/or diversity of pollinating insects. The results of the current study highlights the important role of insect pollinators for almond crops and the urgent need for the implementation of sustainable strategies to preserve pollinators within agricultural ecosystems.

Pollination by multiple species of nectar foraging Hymenoptera in Prasophyllum innubum, a critically endangered orchid of the Australian Alps

Context Australia has numerous threatened species of terrestrial orchid, with a particularly high incidence of rarity in the genus Prasophyllum R.Br. Although there has been research on mycorrhizal associations and propagation, little is known about the reproductive ecology of threatened Prasophyllum. Understanding which animals are responsible for pollination and the impact of herbivores on reproduction may inform conservation actions. Aims For the nationally Critically Endangered Prasophyllum innubum, we aimed to determine the pollinator species, test for self-pollination, quantify levels of reproductive success and herbivory, and identify herbivores. Methods Pollinator observations were undertaken at wild populations of P. innubum, whereas an experiment testing for self-pollination was undertaken in shadehouse conditions. We quantified reproductive success and herbivory at two populations and attempted to identify herbivores using game cameras. Key results Pollination occurred via three species of bee and a sphecid wasp, all of which attempted feeding on floral nectar. Fruit set averaged 72–84% at wild sites, whereas only 6% of flowers set fruit via self-pollination when insects were excluded. Just 4% of inflorescences were completely consumed by herbivores, and no herbivory was captured on camera. Conclusions P. innubum has a generalist rewarding pollination system that confers high levels of reproductive success, with herbivory having little impact on reproduction. Implications Pollinator availability is unlikely to restrict conservation translocation site selection of P. innubum because of a generalist pollination system. If herbivores are a threat for this species, it is likely to be through alteration of habitat rather than direct grazing.

Jasmonate-insensitive mutant jar1b prevents petal elongation and flower opening coupling with parthenocarpic fruit development in Cucurbita pepo

Jasmonates are growth regulators that play a key role in flower development, fruit ripening, root growth, and plant defence. The study explores the coordination of floral organ maturation to ensure proper flower opening for pollination and fertilization. A new mutant (jar1b) was discovered, lacking petal elongation and flower opening but showing normal pistil and stamen development, leading to parthenocarpic fruit development. The mutation also enhanced the elongation of roots while reducing the formation of root hairs. BSA sequencing showed that jar1b is a missense mutation in the gene CpJAR1B, which encodes the enzyme that catalyzes the conjugation between JA and the amino acid isoleucine. The loss of function mutation in CpJAR1B produced a deficiency in biologically active (+) -7-iso-jasmonoyl-L-isoleucine (JA-Ile), which was not complemented by the paralogous gene CpJAR1A or any other redundant gene. Exogenous application of methyl jasmonate (MeJA) demonstrated that jar1b is partially insensitive to JA in both flowers and roots. Further experimentation involving the combination of JA-Ile deficient and ethylene-deficient, and ET insensitive mutations in double mutants revealed that CpJAR1B mediated ET action in female petal maturation and flower opening, but JA and ET have independent additive effects as negative regulators of the set and development of squash fruits. CpJAR1B also regulated the aperture of male flowers in an ethylene-independent manner. The root phenotype of jar1b and effects of external MeJA treatments indicated that CpJAR1B has a dual role in root development, inhibiting the elongation of primary and secondary roots, but promoting the formation of root hairs.

Osmia lignaria (Hymenoptera: Megachilidae) increase pollination of Washington sweet cherry and pear crops.

Apis mellifera Linnaeus (Hymenoptera: Apis), honey bees, are the most widely used managed crop pollinators. However, their high rental cost and uncertain availability for North American orchard crops have motivated growers to explore alternative pollination options. We examined whether adding solitary, spring-flying Osmia lignaria Say (Hymenoptera: Megachilidae), blue orchard bees, as co-pollinators with A. mellifera in Washington sweet cherry and pear orchards enhances fruit set and yield compared to the use of A. mellifera alone. We added managed O. lignaria to orchard sites where A. mellifera hives were already present. Fruit set, fruit yield, and O. lignaria reproduction at O. lignaria-supplemented sites were compared to nearby, paired sites pollinated only by A. mellifera (3 paired cherry and 3 paired pear sites). For both crops, the addition of O. lignaria significantly increased fruit set but did not yield at harvest. Microscopic inspection of pollen grains from O. lignaria nest cell provisions confirmed that O. lignaria primarily visited orchard flowers. Mean retention of O. lignaria in cherry orchards was slightly higher (65%) than O. lignaria retention reported in other orchard crops (30%-60%). However, retention in pear orchards was much lower (≤20%). These results show that supplementing hives with O. lignaria in Washington spring orchard crops can increase overall pollination, but that trees fail to bear developing fruit to maturity. The strategy of using co-pollinators, O. lignaria and A. mellifera, in US orchards may act as "pollination insurance" when A. mellifera hives are in low supply or when the weather is not amenable for A. mellifera flight during the bloom period.

Estimating crop coefficients and water use of a full-bearing mango orchard in north-eastern South Africa using the fraction of vegetation cover and a dual source evapotranspiration model

In semi-arid countries like South Africa, commercially produced mango (Mangifera Indica L.) are grown entirely under irrigation. However, there is little accurate quantitative information on the water use of mango orchards, and few accurate water use models currently exist. In this study, we evaluated the performance of the FAO 56 method of estimating crop evapotranspiration (ETc) and a dual source water use model against measurements of actual consumptive water use of a commercial mango orchard. The FAO approach calculates ETc as the product of a crop coefficient (Kc) and the reference evapotranspiration (ETo). We derived Kc for well-watered orchards from readily available data including the fraction of vegetation cover, average tree height, and a stomatal control coefficient. The dual-source model calculated orchard evapotranspiration as the sum of tree transpiration and orchard floor evaporation derived from the modified Shuttleworth and Wallace model. Actual evapotranspiration was measured using an open path eddy covariance system, while tree transpiration was measured using the heat ratio method of monitoring sap flow. Data were collected in a mature ‘Tommy Atkins’ mango orchard grown with micro-sprinkler irrigation in north-eastern South Africa. Results show that the reference evapotranspiration explained most of the variation in orchard transpiration (R2 ∼ 0.78) compared to the solar radiation (R2 ∼ 0.66) and the vapour pressure deficit of the air (R2 ∼ 0.66). Compared with field measured water use data, the FAO method gave relatively accurate estimates of transpiration (R2 = 0.74, NRMSE = ±18.00 %, NMAE = ±15.00 %, NSE = 0.70) and evapotranspiration (R2 = 0.58, NRMSE = ±19.00 %, NMAE = ±16.00 %, NSE = 0.55). NSE is the Nash-Sutcliffe Efficiency. The dual-source model yielded slightly less accurate estimates of transpiration (R2 = 0.61, NRMSE = ±22.00 %, NMAE = ±20.00 %, NSE = 0.39) and evapotranspiration (R2 = 0.52, NRMSE = ±23.00 %, NMAE = ±25.00 %, NSE = 0.51). The basal crop coefficient (Kcb) showed small seasonal fluctuations, varying between 0.40 and 0.60 throughout the year. In contrast, Kc showed clear seasonality varying between 0.59–0.64 at flowering and fruit set and rising to 0.81–0.90 during the fruit growing phase. Estimates of the annual total transpiration (686 mm) from the FAO method were within 5 % of the actual measured values (677 mm) while the dual source model estimated 612 mm of transpiration, which was almost 10 % lower than the measured values. The results highlight that even though the FAO method requires fewer input parameters, it is potentially more accurate in estimating water use in mango orchards than the dual-source model.

Genetic variability, diversity, and character association for dry fruit yield and quality in chili

ABSTRACT Despite the high nutritional value and extensive consumer preference for chili, productivity levels in India are significantly low. An experiment was carried out to study the variability, genetic diversity, and character association in 30 genotypes. Analysis of variance showed significant differences among genotypes for all the traits under study. A high magnitude of genotypic and phenotypic coefficient of variation, coupled with heritability and genetic advance, was observed for all the traits, except days to first flowering, days to first fruit set, and days to final harvest. Diversity analysis showed that the maximum intercluster distance was observed between clusters IX and XII. Results of correlation and path coefficient analysis indicated that number of fruits per plants, fruit length, fruit weight, green fruit yield per plant, number of seeds per fruit, days to first flowering, and days to final harvest were positively correlated with dry fruit yield. It is concluded that improvement in fruit yield in chili pepper could be achieved by selecting genotypes from clusters IX and XII as parents for hybridization, and traits as components that have positive effect on yield.