Fruit Abortion Research Articles

Insect seed‐predator networks respond positively to restoration on a tropical island

Abstract When non‐native species invade ecosystems, coevolved plant–animal interactions and associated ecological functions are altered, often to the detriment of local biodiversity. While mutualistic interactions can benefit from—and assist with—ecological restoration through the removal of non‐native species, community‐level changes in antagonistic interactions due to restoration are less well understood. Insect seed predators provide important ecosystem functions, but can also have antagonistic effects through pre‐dispersal seed predation which can cause fruit abortion or premature fruit drop, potentially affecting plant community composition. Here, we used a network approach and data on trophic interactions from a large‐scale field experiment to investigate the differences in insect seed predator communities between native restored sites (where non‐native plants were removed) and unrestored sites dominated by non‐native plants on the island of Mahé, Seychelles. Restored sites contained more individuals and species of seed predators (up by 81% and 50% respectively), and experienced a greater predation intensity (1.06 ± 0.53 vs. 0.27 ± 0.09), and predator specialisation compared to unrestored sites. The proportion of predated samples was similar between treatments (~14%). Beta diversity, measured as species and interaction turnover, increased at restored sites. Synthesis and applications: Our findings imply that vegetation restoration generates marked biodiversity benefits on native seed predator communities and their interactions. However, removing non‐native plants did not result in the elimination of non‐native seed predators, which might require targeted control measures. Our results highlight the importance of considering the effects of restoration on antagonistic interactions, in addition to those reported for pollination and seed dispersal services. Management practices should aim to control plant invasions for the conservation of native plant communities that serve as resources and refugia both for mutualists (e.g., seed dispersers and pollinators) and native insect seed‐predator antagonists, both of which benefit native ecosystem function.

High ratio of blue:red light reduces fruit set in sweet pepper, which is associated with low starch content and hormonal changes

In sweet pepper (Capsicum annuum L.), the fruit yield is often negatively affected by fruit abortion. Here we investigated whether fruit abortion is affected by the blue:red light ratio (B:R) and the possible underlying physiological mechanisms related to carbohydrates and hormones. Sweet pepper plants were grown at B:R of 1:10, 1:3, 1:1 or 9:1 with a total photosynthetic photon flux density of 200 µmol m−2 s−1, resulting in a phytochrome photostationary state (PSS) of 0.88, 0.88, 0.86 and 0.72, respectively. For fruit set observations, each plant was allowed to retain 12 flowers on 4 main stems. Sweet pepper plants grown at the highest B:R (9:1) showed a low fruit set (around 3 fruits per plant), whereas the other three treatments resulted in higher fruit set (6–7 fruits per plant). This response matched with the changes in PSS, suggesting the B:R effect on fruit set might be controlled by phytochrome signaling, which requires further investigation. Plant shoot biomass and leaf area were reduced at B:R of 1:1 and 9:1. The reduced fruit set was associated with a drop in starch content and sucrose synthases activity; and a low auxin, high salicylic acid and high cis-Zeatin type levels in flowers. Flowers in the low fruit set treatment also failed to reduce the abscisic acid and ethylene levels after anthesis. We concluded that both the reduced starch content and the hormonal changes in flowers play a role in triggering fruit abortion at the high B:R of 9:1.

ASSESSMENT OF THE IMPACT OF DIFFERENT DEVELOPMENTAL STAGES OF SAHLBERGELLAS INGULARIS HAGL. (HEMIPTERA: MIRIDAE) ON CACAO TREES PRODUCTIVITY AND FRUITS GROWTH UNDER FIELD CONDITIONS IN THE CENTRE REGION OF CAMEROON (CENTRAL AFRICA)

Many studies have addressed the impact of mirids,particularlySahlbergellasingularisspecies on cocoa production in WestAfrica. However the effects of different developmental stagesof this insect on host plant remainunknown.This work aimed to evaluate the impact of the different stages of S. singularis on the productivity and growth of the fruits of Amelonado and Trinitariococoa varieties. We counted the number of feeding punctures on fruits as well ascherellesabortion, and measured the size of the surviving specimens then compared these with the control. The observations showed that all the development stages feed on cherelles. The number of feeding punctures upgraded from the larvae L1 stage to L5 irrespective to the cocoa variety, but Amelonado was more infested thanTrinitario. Within each cocoa variety, significant differencesin feeding punctures and aborted cherelles due toS. singularis developmental stages were observed. Trinitariowas relatively more susceptible than Amelonado to all developmental stages of S. singularis and recorded a higher number of abortedcherelles, values ranged from 58%for L1 to 100% for L5.Irrespective of the cocoa variety, these results showed thatolder mirid larval stages(L3, L4 and L5)significantly induced more damage on cocoa productivity, regarding cherelles abortion and size reduction of theinfected fruits. Overall, our findings showed that, compared toyounger larvae (L1 and L2),older ones and adults are more damaging for cocoa production and the economy this data should be incorporated in the IPM programs against S. singularis.

Far-red light-enhanced apical dominance stimulates flower and fruit abortion in sweet pepper.

Far-red radiation affects many plant processes, including reproductive organ abortion. Our research aimed to determine the role of apical dominance in far-red light-induced flower and fruit abortion in sweet pepper (Capsicum annuum L.). We conducted several climate room experiments where plants were grown under white- or red-rich LED light, with or without additional far-red light. Additional far-red light enhanced apical dominance: it increased auxin levels in the apices of dominant shoots, and caused a greater difference in internode length and apical auxin levels between dominant and subordinate shoots. Additional far-red light stimulated fruit abortion in intact plants but not in decapitated plants, suggesting a crucial role of shoot apices in this effect. However, reducing basipetal auxin transport in the stems with N-1-naphthylphthalamic acid did not influence far-red light-stimulated fruit abortion, although auxin levels in the stem were largely reduced. Applying the synthetic auxin 1-naphthaleneacetic acid on decapitated apices did not influence fruit abortion. However, applying the auxin biosynthesis inhibitor yucasin to shoot apices reduced fruit abortion regardless of the light conditions, accompanied by slight shoot growth retardation. These findings suggest that the basipetal auxin stream does not mediate far-red light-stimulated fruit abortion. Far-red light-stimulated fruit abortion was associated with reduced sucrose accumulation and lower invertase activities in flowers. We suggest that under additional far-red light conditions, increased auxin levels in shoot apices promote fruit abortion probably through enhanced competition for assimilates between apices and flowers, which limits assimilate import into flowers.

Conservation genetics of Notelaea lloydii (Oleaceae) in south-eastern Queensland, Australia.

Habitat fragmentation can increase the chance of population bottlenecks and inbreeding, and may ultimately lead to reduced fitness and local extinction. Notelaea lloydii is a native olive species endemic to Australia and listed as vulnerable due to its restricted distribution. A recent molecular systematics study has revealed there might be some geographic structuring among N. lloydii populations. Therefore, we undertook a genome-wide single nucleotide polymorphism (SNP) analysis to determine levels and patterns of genetic diversity, inbreeding and gene flow within and among N. lloydii populations in south-eastern Queensland. Furthermore, as the reproductive phase of a plant's life history has a profound influence on genetic diversity, life history reproductive traits were also studied. Our SNP analysis revealed low genetic diversity, inbreeding and significant genetic structuring even among proximate populations. Results of a flower and fruit bagging experiment in two consecutive seasons revealed that N. lloydii produced many flowers but only a few fruits survived to maturity. There were no differences in bagged and un-bagged flowering and fruiting rates, and therefore, we conclude that the high fruit abortion rate was probably due to inbreeding depression and/or suboptimal conditions, rather than pollinator availability and insect attack. Overall, results of this study indicate that the populations of N. lloydii are small, inbred and genetically isolated and represent unique management units that require local conservation management due to ongoing threats associated with urbanisation.

Condições meteorológicas afetam o desenvolvimento sazonal e a produção de frutos de coqueiro-anão-verde

ABSTRACT Understanding the green dwarf coconut palm development is essential to improve its management. This study aimed to characterize and understand the seasonality of the green dwarf coconut palm development and yield under rainfed and irrigated conditions in the northeastern region of the Pará state, Brazil. The longitudinal and transverse diameters, fruit mass and yield, in addition to the number of live leaves, live bunches, fruits of the bunches nº 11 and 14 and female fowers were monitored. The coconuts between the bunches nº 20 and 22 showed larger dimensions and biomass (fresh and dry). The partition of the production components varies according to the time of the year, with the liquid albumen mass, which is a component of greater commercial focus, being higher in the rainy season, with lower percentage losses in the irrigated cultivation. The meteorological seasonality plays a key role in fower dropping and fruit abortion, directly contributing to the amount of produced fruits.

Traditional knowledge of tree “bleeding” in brazil nut tree (Bertholletia excelsa) management

The Brazil nut or Amazonian-nut tree (Bertholletia excelsa) is native to the Amazon with a long history of management by traditional populations (or extractivists). “Bleeding” is a management practice in which the trunk is cut to expel resin and bolster fruit production. The objective of this paper was to describe how this practice is perceived and performed by extractivists in three extractive reserves (reservas extrativistas or Resex): Rio Ouro Preto (in the state of Rondônia, RO), Rio Cautário (RO), and Chico Mendes (in Acre, AC). First, semi-structured interviews were conducted in nine communities, sampling at least 30% of the families in each community. Subsequently, to understand variation in how this practice is performed, we used snowball sampling and applied another questionnaire to extractivists who executed bleeding. Almost all extractivists knew of the practice, but not all engaged in it. Many extractivists believed that expelling the resin prevents fruit abortion and improves production.

Embryo Rescue Technique in Buckwheat Fagopyrum esculentum Moench.

Culture of immature buckwheat embryos is an excellent explant for tissue culture and regeneration in vitro, as well as a method of embryo rescue in case of fruit abortion especially in interspecific crosses. Here, we describe the method of immature embryo rescue using a differentiated approach to different age groups. The method involves the development of embryos along the path of direct embryogenesis bypassing the callus stage.

Incidence and frequency of desynapsis in Eremurus persicus (Jaub. & Spach) Boiss.(Asphodelaceae) – A native and important medicinal plant species of Western Himalaya

Eremurus persicus (Jaub. & Spach) Boiss. (Asphodelaceae); a little known species of genus Eremurus grows in arid and semi-arid regions, on rocky mountains in Central Asia and Middle East. The species is native and an important medicinal plant used to treat various diseases. In the current study, we examined male meiosis, karyotypic variability, pollen viability and reproductive output of three populations of the target species. All the studied populations have diploid chromosome count of 2n = 2x =14. Meiotic course in majority of the pollen mother cells (PMCs) in all the three populations is not normal due to the presence of desynapsis at diplotene and metaphase-I. Instead of 7IIs most of the PMCs examined reveal varying number of bivalents and univalents. Anaphasic segregation is also affected in few PMCs. Present study also revealed that the species has asymmetric karyotype of 10 long and 4 short chromosomes. Species exhibits fruit abortion that results in extremely low fruit/seed set. The meiotic abnormalities and low fruit/seed set may be attributed to restricted distribution of this important plant species. Present study may prove helpful in devising the conservation and management strategies for this prized plant species.

First Report of Cucurbita Blossom Blight and Fruit Rot Caused by Choanephora cucurbitarum in Mexico.

In December 2022, blossom blight, abortion, and soft rot of fruits were observed on Cucurbita pepo L. var. Zucchini in Mexico under greenhouse conditions (temperatures of 10 to 32°C and relative humidity up to 90%). The disease incidence in about 50 plants analyzed was around 70% with a severity of nearly 90%. Mycelial growth on flower petals and fruit rot with brown sporangiophores was observed. Ten disinfested fruit tissues in 1% NaClO for 5 min and then rinsed twice in distilled water from the lesion edges were placed on potato dextrose agar culture medium (PDA) supplemented with acid lactic and then, the morphological characterization was carried out in V8 agar medium. After 48 h of growth at 27°C, the colonies were pale yellow with diffuse cottony mycelia that were non-septate and hyaline and produced both sporangiophores bearing sporangiola and sporangia. The sporangiola were brown, ranged from ellipsoid to ovoid, and had longitudinal striations that measured 22.7 to 40.5 (29.8) μm x 16.08 to 21.9 (14.5) μm long and wide, respectively (n=100). The sporangia were subglobose, had a diameter of 127.2 to 281.09 (201.7) μm (n=50), and contained ovoid sporangiospores that measured 26.5 to 63.1 (46.7) μm x 20.07 to 34.7 (26.3) μm long and wide, respectively (n=100) which had hyaline appendages at the ends. Based on these characteristics, the fungus was identified as Choanephora cucurbitarum (Ji-Hyun et al. 2016). For molecular identification, DNA fragments for the internal transcribed spacer (ITS) and the large subunit rRNA 28S (LSU) regions for two representative strains (CCCFMx01 and CCCFMx02) were amplified and sequenced with the primer pairs ITS1-ITS4 and NL1-LR3 (White et al. 1990; Vilgalys and Hester 1990). The ITS and LSU sequences were deposited in GenBank database (Accession numbers OQ269823-24 and OQ269827-28, respectively) for both strains. The Blast alignment showed from 99.84 to 100% identity with Choanephora cucurbitarum strains JPC1 (MH041502, MH041504), CCUB1293 (MN897836), PLR2 (OL790293), and CBS 178.76 (JN206235, MT523842). To confirm the specie identification, the evolutionary analyses were conducted from the concatenated sequences of the ITS and LSU of C. cucurbitarum and other mucoralean species with the Maximum Likelihood method and Tamura-Nei model included in the software MEGA11. The pathogenicity test was demonstrated using five surface-sterilized zucchini fruits inoculated with a sporangiospores suspension containing a concentration of 1 x 105 esp/mL on two sites per fruit (20 µL each) that previously were wounded with a sterile needle. For fruit control, 20 µL of sterile water was used. Three days after inoculation under humidity conditions at 27°C, white mycelia and sporangiola growth with a soaked lesion were observed. That fruit damage was not observed on the control fruits. C.cucurbitarum was reisolated from lesions on PDA and V8 medium which was confirmed by morphological characterization fulfilling Koch's postulates. Blossom blight, abortion, and soft rot of fruits caused by C. cucurbitarum were observed on Cucurbita pepo and C. moschata in Slovenia and Sri Lanka (Žerjav and Schroers 2019; Emmanuel et al. 2021). This pathogen has the capability to infect a wide variety of plants worldwide (Kumar et al. 2022; Ryu et al. 2022). There are no reports of C. cucurbitarum causing agricultural losses in Mexico, and this is the first report causing the disease symptoms in Cucurbita pepo in this country; however, this fungus was found in the soil of papaya-producing areas and it is considered an important plant pathogenic fungus. Therefore, strategies for their control are highly recommended to avoid spreading the disease (Cruz-Lachica et al. 2018).

Expression of candidate marker genes of sugar starvation is upregulated in growth-suppressed parthenocarpic cucumber fruit. Novel gene markers for sugar starvation in growth-suppressed cucumber fruit.

To examine the physiological change in the growth suppression and abortion of parthenocarpic cucumber fruit, the expression of candidate marker genes of sugar starvation in relation to growth activity was examined. Fruits that failed to start exponential growth seemed to eventually abort. Hexose concentration of fruits was low in growth-suppressed fruit and increased in normally growing fruit consistent with the vacuolization. The correlation matrix indicated that the transcript levels of the genes, except CsaV3_6G046050 and CsaV3_5G032930, had a highly significant negative correlation with the relative growth rate in fruit length and had highly significant mutual positive correlations, suggesting that the asparagine synthetase gene, Cucumis sativus putative CCCH-type zinc finger protein CsSEF1, C. sativus BTB/POZ domain-containing protein At1g63850-like, CsaV3_3G000800, CsaV3_3G041280, and CsaV3_7G032930 are good markers of sugar starvation in cucumber fruit. The expression of candidate marker genes together with the hexose analysis strongly suggests that severe sugar starvation is occurring in growth-suppressed fruit.

Combined effects of shade and drought on physiology, growth, and yield of mature cocoa trees

Climate models predict decreasing precipitation and increasing air temperature, causing concern for the future of cocoa in the major producing regions worldwide. It has been suggested that shade could alleviate stress by reducing radiation intensity and conserving soil moisture, but few on-farm cocoa studies are testing this hypothesis. Here, for 33 months, we subjected twelve-year cocoa plants in Ghana to three levels of rainwater suppression (full rainwater, 1/3 rainwater suppression and 2/3 rainwater suppression) under full sun or 40 % uniform shade in a split plot design, monitoring soil moisture, physiological parameters, growth, and yield. Volumetric soil moisture (ϴw) contents in the treatments ranged between 0.20 and 0.45 m3m−3 and increased under shade. Rainwater suppression decreased leaf water potentials (ѱw), reaching −1.5 MPa in full sun conditions indicating severe drought. Stomatal conductance (gs) was decreased under the full sun but was not affected by rainwater suppression, illustrating the limited control of water loss in cocoa plants. Although pre-dawn chlorophyll fluorescence (Fv/Fm) indicated photoinhibition, rates of photosynthesis (Pn) were highest in full sun. On the other hand, litter fall was highest in the full sun and under water stress, while diameter growth and carbon accumulation increased in the shade but was negatively affected by rainwater suppression. Abortion of fruits and damage to pods were high under shade, but dry bean yield was higher compared to under the full sun. The absence of interactions between shade treatments and rainwater suppression suggests that shade may improve the performance of cocoa, but not sufficiently to counteract the negative effects of water stress under field conditions.

Limited reproductive interference despite high rates of heterospecific pollen transfer among co-occurring bat-pollinated Burmeistera.

Many tropical plants are bat-pollinated, but these mammals often carry copious, multispecific pollen loads making bat-pollinated plants susceptible to heterospecific pollen deposition and reproductive interference. We investigated pollen transfer between sympatric bat-pollinated Burmeistera species and their response to heterospecific pollen deposition from each other. We quantified conspecific and heterospecific pollen deposition for two populations of B. ceratocarpa, a recipient species in heterospecific pollen transfer interactions, that co-occur with different donor relatives (B. borjensis and B. glabrata). We then used a cross-pollination scheme using pollen mixtures to assess the species' responses to heterospecific pollen deposition in terms of fruit abortion and seed production. Burmeistera ceratocarpa received significantly more heterospecific pollen from its relatives at both sites than its own pollen was deposited on its relatives. However, heterospecific pollen deposition only affected seed production by B. borjensis and B. glabrata, but not by B. ceratocarpa, suggesting that early acting post-pollination barriers buffer the latter against reproductive interference. Crosses between sympatric and allopatric populations suggest that the study species are fully isolated in sympatry, while isolation between allopatric populations is strong but incomplete. We did not observe evidence of reproductive interference among our study species, because either heterospecific pollen deposition did not affect their seed production (B. ceratocarpa) or they receive heterospecific pollen only rarely (B. borjensis and B. glabrata). Frequent heterospecific pollen deposition might favor the evolution of barriers against foreign pollen (as in B. ceratocarpa) that alleviate the competitive costs of sharing low fidelity pollinators with co-occurring species.

Hand pollination under shade trees triples cocoa yield in Brazil’s agroforests

Agricultural diversification can enhance climate resilience, biodiversity conservation, and livelihood in global farming systems. Diverse agroforestry systems with cocoa have been shown to provide all these benefits, but the often-lower yields compared to monocultures limit agroforestry adoption by smallholder farmers. Cocoa yield is pollination-limited, and here, we quantified the effect of hand pollination in cocoa on fruit set, fruit abortion or cherelle wilt, pest and diseases, and number of mature fruits. Experiments were conducted in Bahia, Brazil, along a shade gradient from low [10–30%] to high [70–100%] canopy cover and with cocoa trees grafted with high-yielding varieties. We found on average 331% fruit set, and 300% mature fruit increase (i.e. ripe pods) per tree by enhancing pollination by hand as little as 10% of the flowers/tree, compared to the control (i.e. with only natural pollination). Fruit set, fruit losses, and mature fruit development linked to hand pollination was higher in low compared to highly shaded cocoa areas. We found 31% higher fruit set and 37% higher number of mature fruits in grafted than un-grafted trees. Further, when comparing efforts invested in hand pollination, minimum labor (∼5 min/tree to pollinate 10–30% of the flowers/tree) led to a 871% fruit set and a 750% mature fruit increase under low canopy cover, and intermediate labor (∼15 min/tree to pollinate 40–60% flowers/tree) to a 629% fruit set under high canopy cover. As ∼5–15 min/tree hand pollination can substantially enhance fruit set and number of mature fruits in low as well as high shade management, we recommend performing hand pollination particularly in agroforests under 40–50% canopy cover to create win-win opportunities for high productivity and climate resilience. Future research should focus on the wide range of agroforestry, tree grafting and innovation strategies in all major production regions to capture the long-term variability of hand pollination as a basis to scale-up hand pollination for sustainable cocoa production globally.

VIABILIDADE REPRODUTIVA DE UM HIBRIDO INTERESPECIFICO DE PALMEIRAS BACABAS (OENOCARPUS SPP., ARECACEAE) EM SISTEMAS AGROFLORESTAIS NA REGIÃO DO PEDRAL DO LOURENÇO NO PARÁ

Bacabeiras (Oenocarpus sp.) are palm trees that offer society numerous benefits in terms of extracting their products, including the use of essential oils, fruit pulp and cosmetics. The research was carried out at APA Lago de Tucuruí, in the state of Pará during the years 2019, 2020 and 2021. During the 03 productive cycles that the Bacaba palm trees and the hybrid Oenocarpusx were accompanied, there was no maturation of their fruits, only formation of fruits that undergo abortion before the final phenological stage. Fruit abortion is generally expected in hybrid individuals. The information obtained here about phenotypic characteristics of wild species and interspecific hybrids are of interest for the cultivation of bacabas species, however the use of other genetic, population and molecular analyzes can contribute to more new explanations and the advancement of science in species of Oenocarpus.

Phenology of flowering and seed development of jernang rattan (Daemonorops spp.)

Abstract. Fridayanti N, Widajati E, Ilyas S, Budi SW, Palupi ER. 2023. Phenology of flowering and seed development of jernang rattan (Daemonorops spp.). Biodiversitas 24: 349-358. Jernang rattan has a high economic value due to its resin content in the exocarp, as the raw material of dyes, medicines, and cosmetics. The resin is highest in the immature fruit skin (exocarp); therefore, fruits are harvested before the seed is germinable. As a consequence, regeneration is very scarce, and the species is categorized as a rare plant. This research was aimed at investigating the flowering phenology and seed development of jernang rattan until they reach physiological maturity, when the viability and vigor are at their highest. The flowering phenology was observed based on Biologische Bundesanstalt Bundessortenamt and Chemische Industrie (BBCH), at the inflorescence stage, flowering stage, fruit development stage, and fruit ripening stage. The inflorescence development from flower bud until ready to bloom took 136.4 ±10.9 days for male plants and 141.6 ±16.4 days for female plants. The inflorescence of staminate flowers bloomed longer (29.4 ±2.7 days) than pistillate flowers (15.4 ± 4.0 days). Fruit abortion mostly occurs during the first six months of fruit development, coincides with the nuclear stage of endosperm, and the final seed set is 56%. It takes around 27 months of one reproduction cycle from the appearance of the inflorescence to seed maturity. The fruit reaches physiological maturity approximately at 22 MAA when the seed is of high viability and vigor, and harvesting at 22 MAA is best for seed production. It is recommended to set up a seed production area separated from the resin production area.

Spatial patterns of the leaf crown borer Eupalamides cyparissias (Cramer, 1775) (Lepidoptera: Castiniidae) in coconut (Cocos nucifera L.) tropical region.

The leaf crown borer Eupalamides cyparissias (Cramer, 1775) is an important pest of coconut (Cocos nucifera L.) and other palms (Arecaceae) of economic importance, attacking the base of leaves, inflorescences, and infructescences, increasing fruit abortion. The objective of this study was to evaluate the spatial correlation of the infestation rate of E. cyparissias in coconut plantation blocks in the Brazilian Amazon, from January to December 2019, in the city of Santa Izabel, Pará, Brazil. The study area is a farm subdivided into 157 blocks of a commercial plantation of the green dwarf coconut. The Local Moran's Index was used to evaluate the existence of spatial autocorrelation of the E. cyparissias infestation rate in the 157 blocks with neighboring blocks. The infestation rate was calculated by the ratio between the number of plants attacked by the borer and the total number of plants in a block. There is a significant correlation of the symptomatology of the attack by E. cyparissias in the blocks of the experimental area, which indicates an aggregated pattern of distribution. There is no significant correlation between the attack by the borer and the age of the coconut tree; however there is a significant correlation between the attack by the borer and proximity to forest areas. These results indicate that forest regions are foci of infestation by the borer in coconut plantations.

Jasmonate-deficient mutant lox3a reveals crosstalk between jasmonate and ethylene in the differential regulation of male and female flower opening and early fruit development in Cucurbita pepo.

Jasmonate (JA) has been found to be a relevant hormone in floral development in numerous species, but its function in cucurbit floral development and sex determination is unknown. Crosstalk between JA and ethylene (ET) in the differential regulation of male and female floral development was investigated by using the novel JA-deficient mutant lox3a, and the ET-deficient and -insensitive mutants, aco1a and etr2b, respectively, of Cucurbita pepo. The lox3a mutation suppresses male and female flower opening and induces the development of parthenocarpic fruit. A bulked-segregant analysis coupled with whole genome sequencing and fine mapping approach allowed the identification of lox3a mutation in CpLOX3A, a LIPOXYGENASE gene involved in JA biosynthesis. The reduced JA content and expression of JA-signalling genes in male and female flowers of lox3a, and the rescue of lox3a phenotype by external application of methyl jasmonate (MeJA), demonstrated that JA controls petal elongation and flower opening, as well as fruit abortion in the absence of fertilization. JA also rescued the phenotype of ET mutants aco1a and etr2b, which are both specifically defective in female flower opening and fruit abortion. ET, the sex determining hormone of cucurbits, is induced in female flowers towards anthesis, activating JA production and promoting the aperture of the female flower, and the abortion of the unfertilized ovary. Given the close association between flower closure and parthenocarpic fruit development, we propose that flower opening can act as a switch that triggers fruit set and development in fertilized ovaries, but may alternatively induce the abortion of the unfertilized ovary. Both ET and JA from mature and senescent petals can serve as remote signals that determine the alternative development of the ovary and fruit.

Far-red radiation increases flower and fruit abortion in sweet pepper (Capsicum annuum L.)

• FR (far-red) applied whole day or end of day stimulates flower and fruit abortion. • FR decreases dry matter partitioned to fruits, due to a reduced fruit number. • FR stimulates total shoot biomass production. • FR increases the fraction of dry matter partitioned to the stem. Fruit set is a crucial plant developmental process, determining yield in many crops. Pepper ( Capsicum annuum L.) is a crop with poor fruit set as typically about two-thirds of all flowers abort. A higher light integral improves fruit set. However, the role of light spectrum has hardly been investigated. Opportunities for detailed investigation of light spectrum effects on fruit set have strongly increased with the introduction of narrow-band LED lighting. To investigate whether additional far-red light (FR) influences the fruit set of sweet pepper, a climate chamber experiment was conducted. Four light treatments were applied to pepper plants grown under 130 µmol m −2 s −1 of red/white LED light. Treatments consisted of different intensities of FR (0, 50, 100 µmol m −2 s −1 ) applied throughout the day or applied at the end of day (EOD, 30 min, 30 µmol m −2 s −1 ). Treatments resulted in phytochrome photostationary state (PSS) values of 0.88, 0.77. 0.70 and EOD 0.16, respectively. Fruit set was determined 3 weeks after the last anthesis of the studied flowers. Additional FR light reduced fruit set in sweet pepper, regardless of whether FR light was provided during the whole day or only at the end of the day. Meanwhile, FR led to more stem elongation, more upright branches, and more dry mass partitioning to stems. Additional FR during the daytime increased total shoot dry weight but not when FR was applied at the end of day. Possible reasons for stimulated flower and fruit abortion by additional FR are discussed.

Optimizing textile dyeing wastewater for tomato irrigation through physiochemical, plant nutrient uses and pollution load index of irrigated soil

Reuse of wastewater for vegetable cultivation is becoming popular in order to augment the inadequate irrigation supplies and meet the growing demands of ground water for agriculture and industries production in different regions of the world. This study was investigated to optimize different stages of textile dyeing wastewater (TDW) for irrigation focusing on their effect on growth, yield and physiochemical attributes of tomato, plant nutrient use, heavy metals enrichment and pollution load of the irrigated soil. Textile wastewater were collected from the seven stages of (second wash after scouring and bleaching T2; enzyme treated water T3; second wash after bath drain T4; neutralization treatment T5; second wash after soaping T6; fixing treatment water T7; mixed effluent T8) of a dyeing process for physiochemical characterization and evaluation their irrigation feasibility for tomato cultivation in compare with the ground water (T1). The pot experiment consists of eight irrigation treatments was laid out following a completely randomized block design with three replications. Results showed the presence of plant nutrients and heavy metals in all the studied samples where T8 (mixed effluent) exceeded the limit of agricultural standard for almost all physiological parameters such as TDS, TSS, EC, BOD, COD affording the highest value. T8 also delivered the highest Cl- and heavy metals like Cd, Ni, Cr followed by T4 < T7. As a consequence, these provided comparatively higher enrichment factor (EF), pollution load index (PLI) and sodium absorption ratio (SAR) to transform fresh soil into the category of severe and slightly to moderate saline. Therefore, the yield and physiochemical attributes of tomato were dramatically reduced with T8 and T4 treatment. On the other hand, T2, T3 and T6 treatment had significant positive impact on growth and yield of tomato due to having higher N, P, K, S and lower heavy metals (Cu, Zn, Fe, Pb, Cd, Ni, Cr) than the recommended guideline. These features were contributed to cause minimum EF and PLI in the soil irrigated with T2, T3 and T6 stages of TDW. Correlation matrix demonstrated that EF and PLI of heavy metals (except Cd, Ni) were negatively related to yield, while positively related to SAR and fruit abortion. Although T6 (2nd wash after soaping) performed better in respect to growth, yield, yield attributes and nutrient use efficiency, principal component analysis revealed that T2 (2nd wash after scouring and bleaching) and T3 (enzyme treated water) were also belong to the same group of T6 and T1 (ground water). Thus, it may be suggested that T2, T3 and T6 stages of textile dyeing wastewater could be used profitably without ETP for vegetable cultivation and would effectively supplement not only the nutrient requirement of the crop but may also act as the alternate source of irrigation water. Although, further research is needed to sort out the health risk assessment through the heavy metals’ accumulation in the plant parts after irrigation with different stages of textile dyeing wastewater.