Poor Fruit Set Research Articles

Influence of plant growth substances on reproductive growth, yield and fruit quality of pear (<i>Pyrus communis</i> L.) cv. Punjab Beauty

Under sub-tropical region, poor fruit set is a major constraint in semi-soft pears resulting in lower fruit yield. To study the effect of plant growth substances on fruit production and quality, the plants of pear cv. Punjab Beauty were sprayed with the plant growth substances viz., boric acid (200, 300 ppm), CPPU (5, 10 ppm), NAA (10, 20 ppm) and P-Ca (150, 300 ppm) at full bloom stage. Among all the applied treatments, boric acid @ 200 ppm proved to be most effective with maximum fruit set (6.91 %), fruit retention (59.9 %) and yield (57.8 kg/plant), while, maximum fruit weight (162.3 g) was observed with NAA (20 ppm). The highest internal fruit quality in terms of maximum TSS (12.4o Brix), TSS/acid ratio (53.4) and ascorbic acid (12.8 mg kg-1) was observed in 200 ppm boric acid. However, the total phenol (30.9 mg GAE/100 pulp) and flavonoid (36.1 mg CE/100 pulp) content was significantly higher with NAA (20 ppm). The plant growth substances reduced the polyphenol oxidase activity in fruits. Overall, the application of boric acid (200 ppm) resulted in improved fruit set, yield and quality in pear cv. Punjab Beauty.

Influence of plant growth substances on reproductive growth, yield and fruit quality of pear (<i>Pyrus communis</i> L.) cv. Punjab Beauty

Under sub-tropical region, poor fruit set is a major constraint in semi-soft pears resulting in lower fruit yield. To study the effect of plant growth substances on fruit production and quality, the plants of pear cv. Punjab Beauty were sprayed with the plant growth substances viz., boric acid (200, 300 ppm), CPPU (5, 10 ppm), NAA (10, 20 ppm) and P-Ca (150, 300 ppm) at full bloom stage. Among all the applied treatments, boric acid @ 200 ppm proved to be most effective with maximum fruit set (6.91 %), fruit retention (59.9 %) and yield (57.8 kg/plant), while, maximum fruit weight (162.3 g) was observed with NAA (20 ppm). The highest internal fruit quality in terms of maximum TSS (12.4o Brix), TSS/acid ratio (53.4) and ascorbic acid (12.8 mg kg-1) was observed in 200 ppm boric acid. However, the total phenol (30.9 mg GAE/100 pulp) and flavonoid (36.1 mg CE/100 pulp) content was significantly higher with NAA (20 ppm). The plant growth substances reduced the polyphenol oxidase activity in fruits. Overall, the application of boric acid (200 ppm) resulted in improved fruit set, yield and quality in pear cv. Punjab Beauty.

Zinc and Boron Application Affected a-Fruit Set and Fruit Quality of Date Palm cv. Barhee

Barhee trees were facing the major problem as poor fruit set and low fruits quality (Shees fruits) and the low yield due to inadequate pollination, The date palm female trees under experimental study were uniformed under farm management as irrigation, pollination, pruning and soil fertilization with both mineral (N, P, K and S) and organic fertilizers (animal manure) to investigate the influence of boron and zinc to increasing fruit set and yield, zinc 1,2 and 3 g/l and Boron at 1,2 and 3 ml/l as foliar before pollinated inflorescences and soil application at 10,20 and 30 g/tree two times /month. The obtained results revealed that treated trees with Borax spraying at 2 ml/l + Zn 2 g/l as pre pollination with soil application at 20 ml Borax + 20 g/l Zn induced heavy fruit, flesh and seeds with longest fruits that contributed to the biggest bunch weight and total yield/ tree in addition to higher rates of fruit retention and Flesh fruit weight %, fruit acidity and phenols were reduced. So based on the previous results, spraying inflorescences and soil treatments with Borax and Zn were applied for increasing and enhancing fruit quality and maximum yield of date palm cv. Barhee.

Ethylene Impact on Grapevine Pistil Temperature and Fruit Set

Ethylene is known to stimulate plant respiration, and this later is associated with heat generation. The grapevine fruit set is dependent upon pistil temperature, controlling the pollen germination and ovule fertilization. This led us to test whether ethylene would be able to impact fruit set often limited in cool climate conditions, particularly in the case of Vitis vinifera L. cv. Malbec, a variety prone to poor fruit set. With this cultivar, we ran trials in growth chambers using the ethylene gas and field trials using ethephon as an ethylene precursor. At 14.5 °C ambient temperature, we observed that ethylene at 1 and 10 ppm increased the stigma and pistil temperature to 15 °C, compared to 14.7 °C in controls. This minor temperature rise was associated with an increase of fruit set from 10 to 25%. The field trials, conducted in the South West of France, confirmed this trend. Indeed, spraying a concentration as low as 216 mg/ha of ethephon onto Malbec at full bloom at 16 °C in the shade led to an increase of fruit set from 35 to 45%. These experiments suggest that spraying ultra-low concentrations of ethylene precursors onto the grapevines prone to poor fruit set, during cool mornings, could improve fruit set and reduce crop losses.

Abiotic Stress Management in Vegetable Crops

Vegetables are highly sensitive in nature thus affected by various biotic and abiotic stress. Any adverse effect of non-living elements on living things in a particular habitat is known as abiotic stress. The production and productivity of vegetable crops got highly effected by the extreme event of climate change i.e, heat stress, water stress, drought, heavy rainfall, salinity etc. Vegetables are full of various nutrients which help in lowering the risk of various diseases such as cancer, heart disease, blood pressure, diabetes etc. Most of the vegetables contain more than 90% of water thus highly sensitive to climate change. Sudden change in climatic factors like in temperature affects all stages of plant growth, pollination, flowering and fruiting which directly reduces the yields and quality of major vegetables. Vegetable crops like beans or tomatoes may lose some of their blossoms at such high temperatures, especially in dry or windy conditions, which will lead to a poor fruit set. High temperatures may harm sweet corn pollination and result in inadequately filled ears of corn. Few fruits are produced because cucurbits (the family that includes pumpkins and squash) typically develop mostly male flowers when temperatures are high.

Powdery Mildew A Disease of Grapes And The Fungicides Mode of Action: A Review

Powdery mildew caused by Uncinula necator (Schw.) Burr. is one of the widespread fungal diseases of grapes that have caused economic losses through poor fruit set and low yield substantially. To decrease the inoculum potential, a disease management program must be undertaken early in the season which is imperative to reduce late-season disease problems. Because, without early control of the infection of powdery mildew, often lead to severe problem in the late season. Elemental sulfur was the foremost antifungal utilized for the control of powdery mildew which is still in use as an effective and cheap fungicide for vineyards. Sterolbiosynthesis inhibitors (SI), also called SI fungicides, are the latest products to control powdery mildew effectively. For efficient use of fungicides with no or less resistance to the pathogen, it is appropriate to spray fungicides having different mechanisms of action which are specific in function, and for more efficacy, use a mixture of such fungicides that have no harmful impact on plant growth and environment. So, for effective control of powdery mildew, a protective spray of fungicide before bloom and a subsequent spray of systemic fungicides at the time of berry formation ensure healthy and higher grapes yield. This paper reviewed the powdery mildew infection in grapevines and its effect on yield losses with details of fungicides’ mechanism of action and newly developed fungicides having broad spectrum activities.

Different Floor Management Systems Affect Soil Properties and Initial Development of Apple Tree (Malus × domestica Borkh.) in an Orchard

In order to achieve sustainable food production, non-chemical weed management practices need to be developed for fruit growing. Tailor-made floor management systems enable efficient weed regulation, but they also affect the soil quality in an orchard. In this article, the effects of various floor management systems in a ‘Red Jonaprince’ apple (Malus × domestica Borkh.) orchard on the soil properties and the trees’ nutritional status and initial development during the first two years after the orchard’s establishment were assessed. The experiment was set up in the spring of 2017 in the Experimental Orchard of WULS. ‘Red Jonaprince’ cv. trees grafted on M.9 rootstock were planted with 3.5 × 1 m spacing between them. Different floor management systems were applied to the rows, including the selected organic mulches: Miscanthus × giganteus straw (MG1 and MG2), spent mushroom substrates (SMS1 and SMS2), herbicide strip (HS), clear mechanical soil cultivation (MC), and synthetic black mulch (BC). The organic mulches affected the soil properties significantly. Spent mushroom substrates (SMS1, SMS2) increased the P and K contents in the soil, increased the salinity 10-fold, and retarded the growth in terms of the trunk cross-section area (TCSA) and its increment compared with other systems. Miscanthus × giganteus straw mulch (MG1, MG2) was associated with a more vigorous shoot growth compared with other combinations in the first year of the study as it provided a better tree nitrogen nutritional status. The floor management system affected the generative development of the trees. Mulching with a spent mushroom substrate boosted the flower bud formation intensity, but it did not affect the yielding quantity. Moreover, due to the poor fruit set, the trees mulched with a spent mushroom substrate (SMS2) gave a low initial bearing. High crop loads were noted for the trees treated with black synthetic mulch (BC) and the trees mulched with Miscanthus × giganteus straw (MG1). This was an effect of the tree size rather than the blooming intensity, while there were no differences in the cropping efficiency index (CEI) parameter.

The effective pollination period of the olive cultivar ‘Arbequina’ (Olea europaea L.) in a non-traditional production region

• ‘Arbequina’ is self-incompatible and fully compatible with ‘Coratina’. • The EPP was estimated to be at least seven days by different methodologies. • The EPP is not a limiting factor for ‘Arbequina’ in Uruguay. In non-traditional production regions, olive cultivation is facing challenges sometimes associated with poor fruit set. That is the case of Uruguay, where olive cultivation has reached 7000-planted hectares; however, yields are low and irregular. Uruguay has a temperate climate with particular characteristics that differentiate it from the Mediterranean basin. It presents greater annual rainfall, reaching up to 1600 mm, high relative humidity and high interannual variability in the rainfall and thermal regime. We hypothesized that these environmental conditions may affect the reproductive biology of olive trees, reduce their Effective Pollination Period (EPP) and limit fruit set. For this reason, we determined the EPP for ‘Arbequina’, the main olive cultivar in Uruguay, by two methodologies: sequential pollination of flowers of different ages, and analysis of its components (stigmatic receptivity, ovule viability, and pollen tube growth). We determined the EPP to be of at least 7 days with both methods. Stigmatic receptivity, assessed by the ability to support pollen adhesion and germination, was maintained for at least 20 days after anthesis. More than 50% of the evaluated flowers maintained at least one viable ovule 23 days after anthesis, and pollen tubes required between two and three days to reach an ovule. No differences in pollen tube growth were found in relation to the age of the pistil. Our results indicate that a short EPP is not behind the low yields of ‘Arbequina’ in Uruguay.

Effect of GA3 and NAA on tomato production under protected cultivation in Kaski, Nepal

A field experiment was carried out under naturally ventilated greenhouse to assess the performance of tomato cv. Srijana as influenced by GA 3 and NAA during the summer season of 2018–2019 at Kham Ghale Krishi farm, Pokhara, Kaski, Nepal. The treatments comprised of four levels of Gibberellic Acid (GA 3 ) (i.e., 0 ppm, 25 ppm, 50 ppm and 75 ppm) combined with four different levels of Naphthalene Acetic Acid (NAA) (i.e., 0 ppm, 25 ppm, 50 ppm and 75 ppm). Treatments were replicated thrice in the two factorial RCBD. The results revealed that the fruit yield was significantly influenced by the levels of GA 3 , NAA and their interactions. Among four levels of NAA, the highest yield (109.91metric ton ha-1) of tomato was recorded with NAA @ 25 ppm which was 10.37%, 17.47% and 24.78% higher over NAA @ 0 ppm, NAA @ 50 ppm and NAA @ 75 ppm, respectively. Similarly, a significantly higher yield (103.46metric ton ha-1) of tomato was attained with GA 3 @ 50 ppm and it was 13.91%, 10.31% and 6.74% higher over GA 3 @ 0 ppm, GA 3 @ 25 ppm and GA 3 @ 75 ppm, respectively. Interactions between GA 3 and NAA levels were significant for all yield attributes. Regression analysis on the effect of GA 3 and NAA on the yield of tomato exhibited a polynomial regression equation, while the physical dose of GA 3 and NAA was observed to be 52.65 ppm and 20.29 ppm, respectively. It could be suggested that the production of tomato could be improved by the combined application of GA 3 @ 50 ppm and NAA @ 25 ppm under the controlled condition of Kaski, Nepal. • Average yield per hectare for tomato is very low in summer season particularly due to poor fruit set and flower drop. • GA3 and NAA can be used to address the problem of poor fruiting and flower drop. • Application of GA3 @50 ppm and NAA@25 ppm led to better fruit set and yield under protected condition. • This can boost the yield and encourage tomato growers to use PGR's at proper concentration under protected condition.

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.

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.

Cucurbit crops in temperate Australia are visited more by native solitary bees than by stingless bees

The propagation and management of stingless bees for pollination services is a growing industry in Australia, but we need to better understand in which crops and environments these pollinators are most useful. We investigated the potential of two Australian stingless bee species, Tetragonula carbonaria and Tetragonula hockingsi, to pollinate cucumber and watermelon crops in both field and protected cropping (greenhouse or polytunnel) environments. We recorded floral visitation rates and fruit yield in cucumber and watermelon and characterized the assemblage of wild pollinators visiting both field-grown crops. Of 229 surveys of cucumber flowers and 144 surveys of watermelon flowers in field experiments where T. carbonaria colonies were deployed, no stingless bees were recorded visiting cucumber flowers, and only one was recorded visiting watermelon flowers. Visitor assemblages in both crops were dominated by the introduced Apis mellifera, with a high number of native solitary halictid bees also visiting watermelon flowers. In a no-choice experiment, stingless bee (T. carbonaria and T. hockingsi) visits to watermelon flowers in a polytunnel occurred after four days but were low in number at first, compared to a greenhouse experiment where visits to cucumber flowers occurred only after 22 days and resulted in poor fruit set. In fact, T. hockingsi more readily collected fungal spores than pollen from cucumbers. Our results indicate that T. carbonaria and T. hockingsi do not make major contributions to the pollination of cucumber and watermelon, but other native flower visitors, including halictid bees, may be important pollinators of these crops.

Growth, Development and Yield of Golden Currant (Ribes Aureum Pursh.) Depending on Cultivation System

Abstract Although golden currant has been grown in Latvia for several decades, mainly as ornamental plant, there is little experience on the most suitable cultivation systems for berry production. Two cultivars of golden currant — ‘Laila’ and ‘Uzbekistanskaya Krupnoplodnaya’, were planted in 2017 in two cultivation systems — vertical trellis and shrub form and assessed in the first two seasons with harvest. In addition, plots with and without organic mulch were established in the shrub system. The aim of the study was to investigate the growth, development and yield of golden currant depending on the cultivation system. All plants bloomed abundantly and practically at the same time in both years, while no significant differences were found between cultivation systems and cultivars. The annual growth of shoots in 2020 was significantly affected by the cultivation system — on average 0.66 m in the trellis system, 0.41 m in the shrub system in mulched plots, and 0.43 m in unmulched plots. Cultivar ‘Laila’ tended to produce longer shoots (average 0.51 m) than the ‘Uzbekistanskaya Krupnoplodnaya’ (average 0.47 m). The yield was low because of poor fruit set and did not significantly differ between cultivar and cultivation systems, though cultivar ‘Laila’ and shrub systems still had higher yields.

Effect of foliar spray of gibberellic acid (GA3) and borax on growth, productivity, and quality of tomato (Lycopersicon esculentum Mill.) under protected structure at Kaski, Nepal

Tomato (Lycopersicon esculentum Mill.) is a highly demanded solanaceous vegetable crop in Nepal. Poor vegetative growth, low flowering and fruit set are the major problems in tomato. Thus, an experiment was conducted to improve vegetative growth, flowering, fruiting and productivity of tomato (Nepali Variety Type 2) at Pokhara-14, Kaski, Nepal during spring- summer of 2019 in Split plot arrangement with gibberellic acid (GA3) as main factor and Borax as sub factor, with three replications. The main factor consisted of four concentrations of GA3 (0, 25, 50 and 75 ppm) which was applied thrice as foliar spray at 15, 30 and 45 days after transplanting (DAT) and sub factor consisted three concentrations of borax (0%, 0.25% and 0.5%) which was applied four times as foliar spray at 15, 30, 45 and 60 DAT. Growth characters viz., plant height, leaf area, leaf number, flower number per cluster, fruit number were significantly enhanced with application of 50 ppm GA3 and gave higher productivity (31.65 t ha-1) compared to other concentrations and control. Likewise, foliar spray of borax resulted in higher stem girth, flower clusters, number of flowers per cluster, and TSS content of tomato. Furthermore, borax @ 0.25% gave the highest productivity (30.78 t ha-1). The better effect of 50 ppm GA3 on growth and yield of tomato and effect of 0.25% borax on flowering and yield, makes them promising solutions to the problems of tomato at Kaski, Nepal. Thus, further research should be conducted by using GA3 and borax in several other tomato cultivars in field and under protected structure at different soil type and climatic conditions.

Effect of short-term temperature stress on fruit set and the expression of an auxin reporter gene and auxin synthesis genes in tomato

• Effect of short-term temperature stress was evaluated during 5 days before anthesis. • Auxin-related factors were investigated using Micro-Tom as a model system. • DR5::GUS expression under high temperature was inhibited with the fruit development. • Fruit set and DR5::GUS expression were not inhibited under low-temperature stress. • The expression of ToFZY for auxin synthesis were affected by high-temperature stress. Poor fruit set and growth are known to be caused by temperature stress in tomato cultivation. We focused on the effect of short-term temperature stress on each day during the five days before anthesis. The relationship between temperature stress and auxin-related factors was investigated using an experimental tomato cultivar, Micro-Tom expressing the auxin reporter DR5::GUS as a model system. While DR5::GUS expression in the control plants increased in ovaries and transferred to peduncles during the later developmental stages, that under high-temperature stress was not detected or very low. Some smaller fruit grew even under high-temperature stress probably due to the low level of DR5::GUS expression. Therefore, it was suggested that temporary high-temperature stress at any stage in this study affected the localization of auxin to ovaries and peduncles, and further affected fruit set and growth. By contrast, no decreased fruit set was observed with some delay and recovery of fruit growth under low-temperature stress, and this corresponded to the levels of DR5::GUS expression. The expression of GUS with the promoter of the tomato PIN gene, which is involved in the auxin transport, was not affected by high-temperature stress. On the other hand, the expression of ToFZY genes involved in auxin synthesis were affected by temperature stress, suggesting a part of the mechanism of the decrease in DR5::GUS expression under high-temperature stress.

Flower differentiation and fruiting dynamics in olive trees (Olea europaea): Eco-physiological analysis in the Mediterranean basin

The formation of flowers in sufficient number and quality is a prerequisite for a successful subsequent fruit set. Despite the abundant flowering, olive trees (Olea europea) are characterized by a very low fruit set, and a very severe yield alteration leading to market fluctuation over time. The goal of this paper is to explore and analyze eco-physiological driving factors behind the poor fruit set in Mediterranean olive groves. The key mechanisms causing floral differentiation and extreme yield alternate are functional of plant genetic variability, nutrient competition, and some ecological aspects as a response to climate change. Additionally, olive inflorescence architecture appears to be complex and can vary between cultivars; the olive flower differentiation results in a variable proportion of hermaphrodite, pistillate and staminate flowers among olive cultivars as well as across canopy positions and branches, enhancing nutrient competition between flowers. Self-pollination could be one of the limiting factors for increasing early fruit abscission and extreme alternate fruit-bearing. Hormonal treatments to reduce alternate production in olive trees should be explored. The current review analysis shall help to improve olive grove management, but also for breeding new cultivars more suitable for Mediteranean agro-ecological constraints. Ovule viability and fertilisation, and embryo sac development abnormalities should all be further investigated.

Heat Stress Leads to Poor Fruiting Mainly Due to Inferior Pollen Viability and Reduces Shoot Photosystem II Efficiency in “Da Hong” Pitaya

High summer temperatures (day/night: 40 °C/30 °C) are known to cause poor fruiting, reduced fruit/seed weight, and delayed fruit development in the “Da Hong” red-fleshed pitaya (Hylocereus polyrhizus); however, the mechanisms of these effects are unknown. This study examined how high temperature (HT, 40 °C/30 °C) affects stamen and pistil fertility through pollination combinations and fruit set in “Da Hong” pitaya and evaluated photosystem II (PSII) efficiency in yellowed shoots (cladodes). The in-vitro pollen germination rate was significantly higher at optimal temperature (OT, 30 °C/20 °C) than at HT, which was also associated with a reduced flower length, poor fruit set, small fruit size, and low number of seeds after self-pollination. Meanwhile, fruit set and fruit development were remarkably improved by using the pollens taken from plants grown at OT and moderate temperature (MH, 35 °C/25 °C) after mutual cross pollination, indicating that the reduction in seed number caused by incomplete fertilization due to inferior pollen viability was the main cause of poor fruiting under HT rather than pistil or photoinhibition, although HT treatment was linked to reductions of PSII efficiency at both the adaxial and abaxial ends of shoots. The results suggested that pollen viability was most affected under HT stress; thus, yielding remarkably reduced fruiting.

Floral and Pollen Studies of Fluted Pumpkin (Telfairia occidentalis Hook. F)

The objective of this study is to investigate the occurrence of poor fruit set in Telfairia occidentalis , despite the prolific production of flowers in this plant. Consequently, the floral morphology of the male and female plants with respect to: pollen viability, pollen size count and pollen size distribution for aneuploids and polyploids were examined. Floral buds from the different ( Telfairia occidentalis) plants were collected and the pollen viability was assessed using aceto-carmine stain. Pollen sizes were measured using a micrometer, and counted. Pollen fertility results obtained using the aceto-carmine method shows that pollen fertility in Telfairia occidentalis is very high with a percentage value of 93.6%. Pollen sizes were 60 to 68µm (54.9%), 48 to 60µm (25.48%) and 68 to 80um (17.64%). The relatively wide range of pollen size confirms the presence of aneuploids and unreduced microspores, as pollen grain size is proportional to chromosome number. The development of polyploidy among the land races of fluted pumpkin in Nigeria is thus confirmed. Keywords: Pollen grains, aneuploids, pollen viability, polyploidy, Telfairia occidentalis . DOI: 10.7176/JBAH/11-22-03 Publication date: November 30 th 2021

Influence of Different Training Levels on Fruit Quality and Yield of Tomato (Solanum lycopersicum L.) under the Mid-hill Conditions of Himachal Pradesh

Background: Yield of summer tomato do not always reach the full production potential. Improved management such as, training and pruning could improve the yield and fruit quality of tomatoes. The production of the healthy and improved quality tomato crop depends on various cultural practices like training systems as it prevents overcrowding for sunlight thus improves air circulation under humid and moist conditions where tomato plants are more prone to fungal diseases, avoids poor fruit set and assimilates competition. Methods: The study was carried out during kharif seasons of 2017 and 2018 with Solan Lalima variety, in the Research Farm of Dr. YSP UHF Nauni, Solan, HP to find out the response of plants to management practices on yield, quality and cost of production. The experiment consisting of two planting methods, three mulching treatments, two level of training system, laid out in randomized complete block design with three repetitions. Result: Plants trained to two stem gave the maximum fruit TSS (4.75 oB), ascorbic acid content (30.79 mg/100 g), lycopene content (5.84 mg/100 g) and shelf life (11.35 days). From the economics, it was apparent that tomato produced by the two stem training system exhibited better performance in terms of benefit cost ratio.