Increased Fruit Set Research Articles

Pollen-Pistil Interaction in Response to Pollination Variants in Subtropical Japanese Plum (Prunus salicina Lindl.) Varieties.

The Japanese plum (Prunus salicina Lindl.) is a fruit tree globally cultivated in temperate regions of the world. Its floral biology and yield are affected by several factors, with issues related to self- and cross- (in) compatibility among varieties being emblematic of the whole Rosaceae family. The aim of this work was to elucidate the fruit set, dynamics of pollen tube growth in pistil, and yield and other fruiting attributes, in 'Satluj Purple' and 'Kala Amritsari', probably the most popular subtropical Japanese plum varieties in northern regions of India. Specifically, we examined the response of six different pollination variants, namely to self-pollination, open-pollination with the two cultivars located in adjacent rows, open-pollination with the two cultivars located in distant rows, manual cross-pollination, supplementary pollination, and floral bouquet. During the two years of the investigation, both plum cultivars showed good in vitro pollen germination (on average, above 50%) at different sucrose concentrations, with the highest values for the 'Satluj Purple' and for the 15% concentration. In vivo, the analysis of the pollen growth in the various sections of the style indicated the best performance when pistils of 'Satluj Purple' were pollinated by pollen grains of cv. 'Kala Amritsari'. Cross-pollination also registered faster growth of pollen tube in pistil with the lowest number of incompatible pollen tubes compared to open- and self-pollination. From the productive point of view, cross-pollination showed the most pronounced results among the different pollination variants, with the highest initial fruit set (36.6%) and yield (28.0 kg/tree), and the shorter fruit development in 'Satluj Purple' (fruit set and yield in self-pollinated 'Satluj Purple' trees were 3.3% and 2.0 kg/tree, respectively). Conversely, the use of 'Satluj Purple' pollen for 'Kala Amritsari' showed poor results. Finally, in our study, 'Kala Amritsari' showed self-compatibility. We conclude that the main cause of poor fruit set in 'Satluj Purple' is self-incompatibility. The relevant genotypic-specific effects revealed by the analysis of the various pollination treatments also highlighted the importance of interplanting to increase fruit set and yield for subtropical Japanese plum varieties.

Limiting carbohydrates to trunk and roots improves bud fruitfulness, fruit set and yield in cv. Malbec

Many commercial vineyards of Malbec, the most cultivated grapevine in Argentina, show unstable yield because of variations in bud fruitfulness and the occurrence of “shatter”, characterised by poor fruit set and fruitlet abscission. Shatter can be due to plant material, growing conditions and meteorological events. Among the parameters that determine fruit set efficiency and vine yield, the availability of carbohydrates (CH) plays an essential role. We previously showed that controlling CH partitioning by removing part of the phloem tissue through an annular incision at the base of the fruit shoots (shoot girdling) reduced shatter in Malbec. The objective of this research was to evaluate the partitioning of CH for the different sink organs of the aerial part of the plant when an interruption of phloem flux from leaves to storage organs is imposed by a girdle. Shoot and trunk girdling trials were conducted during the 2018 and 2019 growing seasons, respectively. At flowering, girdling was performed on different plant lots either at the base of the shoot (Base G), above the distal cluster of the shoot (Top G), to the trunk (Trunk G) or no girdling (Control). Most of the yield components were increased by Base G and Trunk G with no significant impact on vegetative growth or fruit quality. Total shoot biomass was not affected in Base G, while a 39 % reduction was observed in Top G, as compared to Control. The partitioning pattern within the shoot was modified by shoot girdling, and Base G favoured the accumulation of CH towards clusters at the expense of lateral shoots. Shoot girdling increased node diameter, bud fruitfulness and inflorescence dry weight of the shoot. Trunk-girdled vines showed an increase in fruit set and total yield at harvest, with no significant impact on vegetative growth. The restriction of CH flow to the trunk and roots by Base G and Trunk G at flowering increased yield components at harvest without affecting vegetative growth or grape quality. These results reinforce our hypothesis that the root system of the vines under study constitutes a strong sink during the flowering period that competes for CH.

New strategy using plant growth regulator AVG to increase fruit set on apples in mild climatic region in southern Brazil

New strategy using plant growth regulator AVG to increase fruit set on apples in mild climatic region in southern Brazil

Traits Associated with Drought Tolerance in Tomato (Solanum lycopersicum L.)

Across the globe, tomato (Solanum lycopersicum L.) is a commonly used vegetable for culinary purposes. Despite its economic importance, its production is decreasing now a days due to the occurrence of various abiotic stresses like drought. Hence, it is important to understand the mechanism of drought tolerance to sustain tomato production. A field experiment was conducted with drought tolerant and susceptible genotypes to understand the mechanism of tolerance or susceptibility. Drought stress was imposed during the flowering stage for 19 days. The physiological traits like relative water content, pigmentation, flower abscission percentage and fruit set percentage were recorded. The results showed that relative water content was decreased by 20.47 % in the SL CBE G 26 and 40.98 % in the SL CBE G 23. However, the flower drop was highest in the line SL CBE G 23 (23.29%) and lowest in SL CBE G 26 (19.14 %) under drought stress. The line SL CBE G 23 had lower fruit set than SL CBE 26. Hence, the study confirmed that SL CBE G 26 is a drought tolerant line and drought tolerance is associated with increased water retention in the tissue, eventually resulting in decreased flower drop and increased fruit set percentage.

"Hong Long" Lychee (Litchi chinensis Sonn.) Is the Optimal Pollinizer for the Main Lychee Cultivars in Israel.

The lychee fruit is in high demand worldwide. However, the yields of many cultivars are low, including the high-quality cultivars “Nuomici” (NMC) and ”Fei Zi Xiao” (FZX), which are very tasty and produce large fruit with a small seed, but tend to shed their fruitlets. In a previous work, we found that cross-hand pollination of “Mauritius” (MA) with pollen of another cultivar increased fruit set and reduced fruit-drop in comparison to self-hand pollination. In the current research, we aimed to identify the optimal pollen donor for three of the main cultivars grown in Israel: MA, FZX, and “Tamuz” (TA). We compared the effect of different pollinizers and found that the Vietnamese cultivar “Hong Long” (HL), which is becoming an important cultivar in Israel, was the optimal pollinizer for the three cultivars. In addition, we found that FZX and TA were not self-fertile under the Israeli environmental conditions since they tend to shed fruitlets that originated from self-fertilization. In contrast, MA is able to fertilize itself, although cross-pollination greatly increased its fruit number and size. We also identified a new PCR marker for lychee, M3, that enabled us to distinguish between self- and cross-fertilized FZX fruits pollinated by HL. Our results indicate that cross-pollination, particularly by HL, has beneficial effects on the production of lychee and it is especially important for cultivars that generate small seeds and tend to shed their fruitlets.

Native pollinators increase fruit set while honeybees decrease the quality of mandarins in family farms

Family farms can benefit from the presence of a diverse set of native pollinators and associated pollination services. In the present study we assessed the effect of flower visitor richness and visitation rate by honeybees and native insects on mandarin production (Citrus reticulata `Criolla´), in ten citrus family farms located in the Dry Chaco region of northwest Argentina. An exclusion experiment was conducted to explore how pollinators influence the fruit set and quality of `Criolla´ mandarin. The influence of features such as local richness and abundance of flowering plants, farm size, and surrounding natural/semi-natural habitats in the diversity of flower visitors was also evaluated. Fruit set in open pollination branches was three times higher than in bagged branches, where flower visitors were excluded. Moreover, the mandarin fruit set increased with a higher native visitation rate, and mandarin quality (fruit weight and size) decreased with a higher honeybee visitation rate. Flower visitor diversity was higher in farmlands with a greater proportion of surrounding natural and semi-natural habitats. Our results demonstrate the negative effects of excessive honeybee visitation on citrus fruit quality and highlight the importance of native pollinators and natural habitat conservation to increase the fruit set and quality of mandarin in family farms.

Adjacent forest moderates insect pollination of oil palm

Natural habitat plays a role in many agroecosystems as a source of pollination services and other ecological spillover, but these effects are largely unquantified in oil palm (Elaeis guineensis), a globally important crop linked to deforestation. In a field experiment in Sumatra, Indonesia, we manipulated floral visitor access to female oil palm inflorescences over a 100 m distance gradient from forest into oil palm and sampled insects with sticky traps placed above male and female inflorescences. Full exclusion of floral visitors decreased mean oil palm fruit set to 12%, demonstrating that insect pollination was necessary to maintain favorable fruit set and yield. Treatment group means of fruit set under open pollination (62%) and when excluding large (>1.4 mm diameter) organisms (72%), did not differ significantly from open pollination augmented with hand pollination (61%), suggesting no difference in pollen limitation. In contrast, when we examined change in fruit set with distance from forest, we found a significant trend of higher fruit set in oil palms closer to the forest when large organisms were excluded, which increased estimated fruit set at the forest edge to 87%, compared to open-pollinated palms (70%). This trend with distance from forest was absent when we fully excluded floral visitors, showing that the effect of forest was not likely due to an abiotic gradient (e.g., changing soil nutrients). Of the arthropod taxa collected from sticky traps, Drosophilidae (Diptera) and Gelechiidae (Lepidoptera) decreased and increased with distance from forest, respectively. The taxa Elaeidobius kamerunicus (Coleoptera: Curculionidae), Gelechiidae, and the families Thripidae and Phlaeothripidae (Thysanoptera) were abundant on both male and female inflorescence sticky traps. Elaeidobius kamerunicus, an introduced oil palm pollinator, had the only significant relationship with fruit set. Our results confirm pollination by insects as a key ecosystem service for oil palm production. Although further work is needed to clarify the relationship between fruit set, biodiversity, and distance from forest, we speculate that excluding large organisms could have increased fruit set closer to forest by mediating interactions between pollinators, forest predators, and farm mesopredators. Understanding the relationships between nearby forest and pollination services could better connect oil palm production to its landscape context and associated biodiversity. This would be important for landscape-scale conservation planning that considers both the ecosystem service needs and ecological impacts of oil palm agriculture.

The Xenia Effect Promotes Fruit Quality and Assists in Optimizing Cross Combinations in ‘O’Neal’ and ‘Emerald’ Blueberry

Cross-pollination can improve the fruit set and quality of blueberry (Vaccinium spp.) for growers and consumers. However, the xenia effect in southern highbush blueberry remains unclear. Therefore, we selected eight cultivars of southern highbush blueberry (Vaccinium corymbosum L., interspecific hybrids) and applied pollination treatments (i.e., artificial self-pollination, artificial pollination with mixed pollen, or artificial pollination with individual cultivar pollen) to explore the xenia effects on the fruit set and quality of ‘O’Neal’ and ‘Emerald’. Pollen viability tests indicated that all of the cultivars are capable of fertilization. The highest fruit set came from ‘Bluerain’ pollen for ‘O’Neal’, while ‘Gulfcoast’ pollen increased fruit set the most in ‘Emerald’. Principal component analysis revealed that the cross combinations ‘Emerald’ × ‘Gulfcoast’ and ‘O’Neal’ × ‘Gulfcoast’ optimized the external and interior quality of the fruit. SSR was applied to determine which pollen source yielded the most seedlings. Results indicated that ‘Emerald’ × ‘Gulfcoast’ and ‘O’Neal’ × ‘Bluerain’ increased seedling production. Our results demonstrate that the xenia effects of ‘Gulfcoast’ pollen may increase ‘Emerald’ yields and promote fruit quality, while pollen from ‘Bluerain’ or ‘Jewel’ can improve ‘O’Neal’ fruit quality and seed number. Hence, these cross combinations may be utilized in blueberry production to increase fruit set, yield, and quality.

Estimated economic value of pollination by Tetragonula laeviceps (Hymenoptera: Apidae: Meliponini) on tomato and chili

Abstract. Mubin N, Kusmita AO, Rohmah A, Nurmansyah A. 2022. Estimated economic value of pollination by Tetragonula laeviceps (Hymenoptera: Apidae: Meliponini) on tomato and chili. Biodiversitas 23: 2544-2552. Insects have various roles, one of which is as pollinators. Horticultural crops such as tomatoes and chilies need the help of pollinating insects to increase productivity. The stingless bee, Tetragonula laeviceps, is one of the potential pollinating agents. This study aimed to determine the effect of pollination by T. laeviceps on crop production and estimated pollinating insect’ economic value. The study was conducted using a field experiment with 3 pollination treatments included pollination with the help of T. laeviceps (open pollination / OP), pollination by wind (WP), and self-pollination (SP). The estimated economic value of pollination was calculated using a bio-economic approach based on the level of dependence of the plant on pollination. The results showed that open pollination (OP) treatment by T. laeviceps increased fruit set and seed set by 2-3 times that of wind pollination and 4-5 times that of self-pollination. The open pollination treatment significantly affected on the diameter and weight of tomato fruit compared to the WP and SP treatments but not on chili. Meanwhile, open pollination can increase the length of chili fruit. OP, WP, and SP treatments had no significant effect on tomatoes and chilies’ weight loss, damage level, and hardness level. Based on tomato and chili production, the economic value of T. laeviceps was 44 times (tomato) and 20 times (chili) from self-pollination and 65 times (tomato) and 11 times (chili) from wind pollination.

Boron Effects on Fruit Set, Yield, Quality and Paternity of Macadamia

Many tree crops experience sub-optimal yields and low fruit quality due to inadequate pollination, low fruit set, and poor crop nutrition. Boron (B) is a critical crop nutrient for fruit set because B levels affect pollen germination and pollen tube growth. However, the relationship between floral B concentration and fruit set is not well understood. The aim of this study was to determine the effect of B applications on the initial fruit set, yield, quality, and paternity of macadamia (Macadamia integrifolia). Cultivar ‘816’ trees received one of three treatments: (a) 0 g, (b) 15 g, or (c) 30 g B per tree prior to flowering. Boron application increased the B concentration of macadamia flowers. Application of 15 g B increased fruit set at 3 weeks after peak anthesis, but this higher initial fruit set was not translated into higher fruit set at 6 or 10 weeks after peak anthesis or higher yield. Boron application increased B concentrations in kernels but did not affect nut-in-shell (NIS) mass, kernel mass, kernel recovery, kernel oil concentration or incidence of whole kernels. Cultivar ‘816’ was highly outcrossing, with 97–98% cross-paternity among kernels from all treatments. Our results indicate that higher B concentration in macadamia flowers can be associated with an increased initial fruit set. However, high B levels did not affect yield, nut quality, or the proportion of self-pollinated fruit at maturity. The heavy dependence on outcrossing highlights the importance of inter-planting different cultivars and managing bee hives to sustain the productivity of macadamia orchards.

Temporal Variation in Pollinators’ Visitation of Lantana camara in a Tropical Urban Landscape: Does Butterfly Abundance and Richness Drive the Fruit Set?

Abstract Pollinator richness, abundance and visitation frequency may be affected by the abundance of floral resources and abiotic factors, influencing plant reproductive success. We analysed whether the diversity, abundance and frequency of butterfly visitation on Lantana camara vary across the year in a tropical urban landscape and whether this variation in butterfly community influences plant’s reproductive success. A two-period survey, referred to here as rainier and drier seasons, was carried out in 12 spatially independent plants. Five pollination treatments were applied: single visit, hand cross-pollination, hand self-pollination, spontaneous self-pollination and open pollination (control). A total of 15,749 flowers were used for fruit production analysis. Butterfly richness, abundance and the reproductive success of L. camara increased in the drier season. Open pollination was ninefold more reproductively successful during the drier season. Fruit production of hand cross-pollinated plants was threefold higher than open-pollinated plants during the rainier season. No significant difference was found between these treatments in the drier season, attesting the highest abundance of pollination during this period. We provide evidence that changes in the pollinator community affect fruit production. The increase in pollinator diversity allows different visitors to pollinate the plant, increasing fruit set through functional complementarity. This effort establishes baseline data of plant–pollinator interactions for further long-term investigations across different weather seasons. The understanding of L. camara and butterflies’ synergism will support conservation measures of pollinator populations.

Synergistic action of humic acid substances and bio-inoculants in guava (Psidium guajava L.): impact on growth traits, fruiting, nutrient profiling and rhizosphere stochiometry in meadow rainy season plant-soil interface

The present investigation was conducted on guava cv. Lalit spaced at 2 m × 1.5 m in meadow plant-soil interface during two consecutive rainy seasons of 2017 and 2018. Foliar application of humic acid was carried out at bud burst stage in two different levels i.e. 30 ml/L (HA30) and 60 ml/L (HA60), bio-inoculants were applied to the rhizosphere of the trees at two combinations, B1: PSB @ 10 ml/plant + Azotobacter chroococcum @ 10 g/plant, and B2: PGPR @ 25 ml/plant + AM fungi @ 25 g/plant along with reduced recommended dose of fertilizers (RDF) of N:P:K (360:740:200) i.e. 90 per cent of RDF (NPK90) and 80 per cent of RDF (NPK80). The experiment was laid out in Randomized Complete Block Design with eight treatment combinations, replicated thrice along with a control. The results showed that application of humic acid at 60 ml/L along with each of PSB and A. chroococcum at 10 ml/plant along with 80 per cent of NPK resulted in growth and fruiting over control. This combination also recorded significant increase in fruit set with marked reduction in fruit drop. Fruit yield was 1.89 times compared to control. Both physical and biochemical fruit quality traits were also significantly affected by this conjoint application. Microbial biomass in terms of actinomycetes, A. chroococcum, PSB and AM fungi were also tremendously increased compared to control. This combination also exhibited considerably greater amount of leaf N (2.55%), leaf P (0.24%) and leaf K (1.32%) under meadow plant-soil interface.

Effect of girdling and root pruning on vegetative growth, fruit metabolites and yield of pear grown under sub-tropical conditions

Excessive vegetative growth in semi-soft pear is a limiting factor for optimum fruit production under sub-tropical conditions of north-western India. Therefore, the present studies were conducted to regulate the vegetative growth and improve fruit yield, quality and associated biochemical parameters of pear cultivar ‘Punjab Beauty’ by girdling and root pruning techniques. The significant increase in fruit set, retention, yield, total phenolics content, flavonoid content and C:N ratio of bark and spur was registered with root pruning at 60 cm as compared to control and the other treatments viz; trunk girdling, limb girdling, root pruning at 40 cm and sub limb girdling. However, fruits with maximum size, weight, total soluble solids (TSS), TSS/Acid ratio were attained with the trunk girdling. The limb girdling and root pruning at 40 cm also enhanced fruit quality but sub-limb girdling did not create significant impact. The fruits of the root pruned trees exhibited a slower oxidation of the total phenol content by inhibiting the activity of polyphenol oxidase and thus retaining higher total phenolic content as compared to control. Hence, root pruning at 60 cm exhibited promising results for controlling vegetative growth, improving yield and fruit biochemical attributes in pear.

Micronutrients and plant growth regulators affecting the yield and quality of fruit crops: A review

The application of micronutrients and plant growth regulators has a greater impact on enhancing plant productive efficiency by altering various aspects of horticultural attributes like a biometric response, fruiting potential, and qualitative parameters. All metabolic and cellular processes of fruit crops are influenced by micronutrients. The role of boron and zinc are well-known for nitrogen metabolism, cell division, and hormonal regulation which ultimately end with proliferation in flowering and fruiting by increasing fruit set and reducing fruit drop. The role of plant growth regulators (PGR) in plants in changing or normalizing the physiological cycle to create better plant health is well known. Hence, the combination of both these growth-promoting substances (micronutrients and PGR) in an optimum amount can positively and significantly influence the physiological activities of the plant. However, the literature regarding the combined effect of micronutrients and PGR on fruit crops is very limited. So this review paper focuses on the combined effect of these plant bio-stimulants, showcasing their remarkable role in fruit production.

EFFECT OF TRYPTOPHAN, SALICYLIC AND ASCORBIC ACIDS ON PRODUCTIVITY AND FRUIT QUALITY OF NAVEL ORANGE TREES

A field experiment was carried out during the 2019 and 2020 seasons on 12-year-old Navel orange trees grown in El Bustan district, El Behera Governorate, Egypt. Three concentrations (25, 50 and 75 ppm) of tryptophan, (100, 200 and 300 ppm) of salicylic, and (500, 750 and 1000 ppm) of ascorbic as well as the control (tape water) were foliar application three times a year, i.e., at full bloom stage and the second one was performed just after fruit setting and the third was sprayed four weeks later. The results showed that, tryptophan treatment at 75 ppm improved shoot length, tree height, tree canopy volume, fruit weight, fruit length, fruit diameter, and fruit volume. Moreover, salicylic as foliar application at 300 ppm increased fruit set percentage, fruit retention percentage, numbers of fruits/ tree, yield, yield efficiency, peel thickness, juice weight, fruit juice percentage, TSS, ascorbic acid content, and total sugars content.

Increasing yield and quality of citrus by pruning and fertilization

Pruning and fertilization are factors that can determine the production and quality of citrus. The objective of this study was to determine the effect of pruning intensity and fertilizer doses of N (nitrogen), P (phosporus), and K (potassium) on citrus production and quality. The study was carried out in a citrus orchard in Central Java, Indonesia, over the course of two seasons, 2016-17 and 2017-18.The experiment was conducted as a two-factorial, completely randomized block design where the first factor was pruning intensity, namely 0, 5, 10, and 15 % of the total number of branches per tree while the second factor was doses of N, P, and K fertilizers, namely 0, 2, and 4 % of the weight of harvested citrus fruit in the previous season. The result showed that increasing doses of N, P, K fertilizers from 0 to 4 % increased fruit set, harvested fruits, fruit size, content of vitamin C, sugar, and soluble solid. The highest fruit set, weight of harvested fruits, and content of vitamin C were achieved by pruning intensity of 10 %.

Increasing off-season snake fruit (Salacca zalacca) yield by preventing fruit set failure with different exogenous auxin spray

Snake fruit blooms every three months, but only one to two of the flowering seasons result in fruit production. Failure of fruit set causes the fruit harvest seasonally. Therefore, the aim of this research was to increase off-season production by preventing the failure of fruit set with various exogenous auxin spray. The research was conducted in the snake fruit orchard at Bebandem Sub-District, Karangasem Regency, Bali Province, Indonesia, from February to November 2019. The experiment was designed as a nested factorial with a randomized block design. The treatment consisted of three types of auxin with a specific concentration for each, IAA at 0, 25, 50 and 75 ppm, IBA at 0, 50, 100 and 150 ppm, and NAA at 0, 50, 100 and 150 ppm. The IAA, IBA, and NAA were sprayed on the flowers and leaves 3 times in March, April, and May. The results showed the highest percentage of fruit set, fruit weight per tree, and weight per fruit obtained with IAA treatment were 59.80 %, 2,612.91 g, and 91.06 g, respectively. These results were not statistically different to those of the IBA and NAA. Furthermore, the IAA concentration of 25, 50, and 75 ppm produced a significantly higher percentage of fruit set compared with the control. The increased fruit set in the IAA, IBA and NAA treatments resulted in better yield than the control. The novelty of this result is that spraying snake fruit with IAA, IBA and NAA can prevent the failure of the fruit set. Therefore, IAA, IBA, and NAA are recommended to be applied to increase off-season fruit production of snake fruit.

PHENOLOGY OF ANNUAL DORMANCY RELEASE AND ITS ASSOCIATION WITH FRUIT SET OF DIRCA OCCIDENTALIS (THYMELAEACEAE)

Weather and climate may influence the phenology of Dirca occidentalis A.Gray (Thymelaeaceae) in ways that impact reproductive success. Dirca occidentalis blooms during winter, when the likelihood of entomophily may be low. Based on preliminary observations that the timing of dormancy release and growth resumption varies over years and among shrubs within years, we quantified fruit set among flowers that formed at different times and examined whether annual variation in autumnal precipitation and temperature during autumn and winter are associated with phenology. Fruit set was determined during 2007–2008 through 2011–2012 by tracking 37,461 flowers near or at anthesis early, midway, and late within the blooming period of D. occidentalis. In addition, measures of phenology of 18 individual shrubs were made each December 29, January 26, and February 23 of the five blooming periods, and fruit set of these shrubs was determined. Fruit set was low (<5%) among flowers present early (December 26–January 2), but increased significantly in all blooming periods, to as high as nearly 30%, among flowers at anthesis later. Phenology ratings, and lengths of newly formed stems and leaves, on December 29 increased linearly as the amount of precipitation from October 1–December 15 of the same year increased. Phenology ratings on February 23 increased linearly with increasing air temperature from November 1–February 23. Rankings of phenology of the 18 shrubs were highly correlated over years, and fruit set of individual shrubs over years was 1% to 52% and increased linearly as growth resumption and flowering became later. Our results demonstrate that low autumnal precipitation is associated with delayed growth resumption and flowering, which corresponds with increased fruit set of this rare species.

PP 1/185 (3) Regulation of growth in olive (except sucker control)

Specific scopeThis Standard describes the conduct of trials for the efficacy evaluation of plant growth regulators used on olive for the following uses: improvement of shoot growth, increase of flowering, increase of fruit set, fruit thinning, promoting fruit abscission, regulation of biennial bearing.Specific approval and amendmentFirst approved in 1993‐09.Aligned with revised standard text in 1998.Second revision approved in 2021‐09.Authors and contributors are given in the Acknowledgements section.

Vanillaflowers: much more than food-deception

AbstractIn many flowering plants the attraction of pollinators is related to some kind of deception. Pollination by food-deception occurs in several angiosperm groups and is particularly widespread in orchids. Despite the apparent evolutionary success of pollination by food-deception, food-deceptive orchids show a low level of fruit set. Although studies are scarce, the pollination of Vanilla has been usually associated with nectar-deception. In Vanilla spp. (Vanilla bahiana, V. bicolor, V. chamissonis, V. edwallii, V. hartii, V. phaeantha, V. paulista, V. planifolia, V. ribeiroi and V. pompona), understanding the factors associated with pollinators is essential, since in vanilla production a cumbersome process of supplementary manual pollination is necessary to increase fruit set, which is frequently low under natural conditions. The production of floral rewards was investigated here in ten Neotropical Vanilla spp. based on morpho-anatomy and histochemical analyses of flowers. Six species (Vanilla bahiana, Vanilla bicolor, Vanilla chamissonis, Vanilla hartii, Vanilla phaeantha and Vanilla pompona) offer nectar as a reward. In Vanilla ribeiroi, the long trichomes of the labellum base are rich in starch grains and proteins, characteristic of food-hairs. The only secretory structures of Vanilla edwallii are osmophores on the inner surface of the labellum that are related to the attraction of oil-collecting bees as pollinators. Vanilla spp. possess sepaline and labellar osmophores. Inside the labellum the osmophores are arranged along longitudinal lines and act as resource guides. Although it is widely known that Vanilla flowers attract pollinators by nectar deception, the present data reveal that there may be a lack of knowledge regarding pollination in this group since the offer of nectar appears to be a common condition, at least for the euglossine-pollinated Neotropical clade. The remaining Neotropical groups exhibit other pollination strategies, such as the production of food-hairs and fragrances that attract oil-collecting bees to the flowers. The study of Vanilla pollination is extremely important because the need for manual pollination, added to the ripening and curing time, causes vanilla to be one of the most expensive spices in the world. According to the data presented here, the pollination systems of vanilla are much more diverse than classical “food deception”.