Pollination Conditions Research Articles

Evaluation of the Bioactive Compounds of Apis mellifera Honey Obtained from the Açai (Euterpe oleracea) Floral Nectar.

The biodiversity of Brazil provides an excellent climate and favorable pollination conditions for Apis mellifera L., especially in the Eastern Amazon region, which boasts vast floral wealth, including an abundance of açaí (Euterpe oleracea) flowers and fruits. In the present study, seven types of honey were evaluated: three containing floral nectar from açaí (Açaí honey) collected in the Eastern Amazon region (Açaí honey from Breu Branco (AH1 and AH2) and Açaí honey from Santa Maria (AH3), both from the state of Pará, Brazil) and four honeys from different regions of Brazil (Aroeira honey from Minas Gerais, Cipó-Uva honey from Distrito Federal, Mangue honey from Pará, and Timbó honey from Rio Grande do Sul). The characteristics of these honeys were evaluated by examining their physicochemical properties, melissopalynological aspects, color, antioxidant potential, and their constituent compounds, which were confirmed through GC-MS analysis. Açaí floral nectar honeys presented physicochemical results similar to those of other honeys, aligning with Brazilian legislation norms, but differed in their high values of free acidity, apparent sugars, and lower reducing sugars, which are directly related to their botanical origin. These differences correlate with unique flavor and distinct aroma characteristics. Melissopalynological analysis confirmed the botanical origin of the honeys containing açaí floral nectar, which had a color range from amber to dark amber. The three açaí honeys demonstrated high antioxidant capacity and superior flavonoid and polyphenol content compared to other honeys, particularly the açaí honey from Breu Branco (AH1), which had four times the content to combat free radicals compared to the honey with the highest potential (Aroeira honey). GC-MS analysis confirmed the presence of antioxidant properties as well as potential anti-inflammatory, antibacterial, antimicrobial, and antitumor capabilities in açaí honeys, which have not yet been fully studied.

ESTABLISHMENT OF PHENOTYPIC VARIABILITY AND CORRELATIONS OF SEED YIELD AND YIELD RELATED TRAITS IN ALFALFA (Medicago sativa L.) CLONAL PROGENIES

The aim of present study was to evaluate phenotypic variability of seed yield and yield-related traits and to establish the relationships among them at eleven alfalfa clonal progenies. The study was conducted in experimental field at Institute of Agriculture and Seed Science Obraztsov chiflik - Ruse under conditions of open pollination (polycross), from 2014 to 2016. The traits plant seed yield, plant height, generative stem number, inflorescence number, pod number, seed number and 1000-seed weight were evaluated. The factors year, genotype and year x genotype interaction had a significant influence on all morphological and generative traits. There was wide range of variability for all analized traits between progenies and over study period. PM30 progeny showed superior scores regarding all traits studied and four progenies distinguished with high phenotypic expression of seed yield, pod number, seed number and 1000-seed weight. These progenies are valuable germplasm source to be used in further breeding to develop a new synthetic alfalfa variety with stable seed yield. It was found seed yield strongly and positively correlated with plant height, seed number per pod and pod number per inflorescence, wtich suggest that selection for improving alfalfa seed yield may be performed directly through selection on these three traits.

Evaluation of the Pollination Efficiency of Apple Trees by Osmia excavata Alfken (Hymenoptera: Megachilidae).

The mason bee Osmia excavata Alfken is an apple pollinating insect widely distributed in northern China, in order to effectively utilize the mason bee and improve the pollination rate of apples, there is a need to evaluate the pollination efficiency of the bees. This study evaluated the pollination efficiency of the mason bee on apple orchards in Jinan and Yantai, Shandong Province, China. The study compared natural pollination areas and pollination areas with different release densities of O. excavata in terms of the effects of bee density, timing of pollination, and distance effects on fruit set rate, fruit shape index, fruit shape skewness, fruit soluble solids content, and fruit firmness. The optimal release density of bees was 6000 cocoons per hectare, resulting in the highest fruit setting rate of apple lateral flowers. From 07:00 to 14:00 was the best time for bee pollination. The optimal distance of hives from apple trees for pollination by O. excavata was 60m. Single fruit weight was significantly higher and fruit unsymmetrical rate, partial slope and hardness were all significantly lower at the release densities of 6000 or 12000 cocoons per hectare compared with 3000 cocoons per hectare or under natural pollination conditions. There was no significant difference in the content of soluble solids under different release densities. Thus, the radius of 60m from the hive was the effective pollination range and 6000 cocoons per hectare of mason bees could ensure the fruit quality of apple.

Comparative stigmatic transcriptomics reveals self and cross pollination responses to heteromorphic incompatibility in Plumbago auriculata Lam.

"Heteromorphic self-incompatibility" (HetSI) in plants is a mechanism of defense to avoid self-pollination and promote outcrossing. However, the molecular mechanism underlying HetSI remains largely unknown. In this study, RNA-seq was conducted to explore the molecular mechanisms underlying self-compatible (SC, "T × P" and "P × T") and self-incompatible (SI, "T × T" and "P × P") pollination in the two types of flowers of Plumbago auriculata Lam. which is a representative HetSI plant. By comparing "T × P" vs. "T × T", 3773 (1407 upregulated and 2366 downregulated) differentially expressed genes (DEGs) were identified, 1261 DEGs between "P × T" and "P × P" (502 upregulated and 759 downregulated). The processes in which these DEGs were significantly enriched were "MAPK (Mitogen-Activated Protein Kinases-plant) signaling pathway", "plant-pathogen interaction","plant hormone signal transduction", and "pentose and glucuronate interconversion" pathways. Surprisingly, we discovered that under various pollination conditions, multiple notable genes that may be involved in HetSI exhibited distinct regulation. We can infer that the HetSI strategy might be unique in P. auriculata. It was similar to "sporophytic self-incompatibility" (SSI) but the HetSI mechanisms in pin and thrum flowers are diverse. In this study, new hypotheses and inferences were proposed, which can provide a reference for crop production and breeding.

Extra-stigmatic pollen germination and pistil elongation: a novel strategy towards reproductive assurance in Dodonaea viscosa subsp. angustifolia

Context Reproductive success in dioecious plant species may be limited by severe pollen limitation owing to their separate sexes and pollination barriers. Aims Dodonaea viscosa subsp. angustifolia (Jacq.) (Sapindaceae) is a dioecious and wind-pollinated species that has a long flowering period. This study sought to determine the relationship between its reproductive behaviour and pollen availability during different flowering phases. Methods Extra-stigmatic pollen germination and reproductive performance during different phases of flowering were investigated and correlated with pistil elongation under natural conditions. Results The species offers whole stigmatic and stylar surfaces for pollen to land and germinate under natural conditions. During pollen-limiting conditions, the length of the pistil increases significantly to enhance pollen capture. Depending on where on the pistil pollen lands, the timing of pollen tube arrival at the ovary varies. Conclusions Dodonaea viscosa subsp. angustifolia is the first reported wild species in the Sapindaceae where pistil elongation is regulated by pollination conditions and extra-stigmatic pollen germination ensures reproduction during phases of differing pollen availability. Our results indicated that the flexibility of female function and reproductive behaviour in Dodonaea viscosa subsp. angustifolia adds to the evolutionary possibilities to overcome pollination constraints. Implications This unique strategy for increasing female fitness through pollen presentation in D. viscosa subsp. angustifolia could be explored in other subspecies of D. viscosa on the Australian subcontinent.

Parthenocarpic fruit quality and production under pollinator-exclusion in southern highbush blueberry

Parthenocarpy is the phenomenon of seedless fruit formation without fertilization. This trait has drawn the attention of many fruit and vegetable breeders due to its ability to overcome insufficient pollination and secure yield. Blueberry (Vaccinium spp.) maintains one of the highest pollination requirements of all crops, demanding growers invest in seasonal pollination services. Nevertheless, blueberry continues to suffer from suboptimal fruit set due to ineffective honeybee pollination, and adverse weather conditions during the brief bloom period. Therefore, developing parthenocarpic blueberry cultivars could provide an economical and effective way to ensure fruit set with decreased dependency on seasonal pollination services. However, the effects of parthenocarpy on berry quality and production-related traits in blueberry is unknown. Therefore, this study aims to evaluate these characteristics in 13 southern highbush blueberry genotypes under two pollination conditions (open-pollination and pollinator-exclusion cages). Open-pollinated and non-pollinated fruits from the 13 blueberry genotypes were assessed for seededness, firmness, size, sugar-to-acid ratio, fruit set, yield, week of peak harvest, and the duration of the fruit development period. Non-pollinated parthenocarpic fruits took longer to develop and tended to be smaller, sweeter, and less firm than open-pollinated fruits. Despite these differences, most parthenocarpic fruits still met market standards. Genotypic differences were also observed, suggesting the opportunity to select for enhanced parthenocarpy in future populations. The results of this study demonstrate that facultative parthenocarpy can be exploited and incorporated into blueberry breeding programs to ensure proper yield in inadequate pollination conditions.

Use of the biostimulant Retard Cherry® as a strategy to delay blooming period in sweet cherry trees

Spring frosts are a limiting factor in sweet cherry production in central-southern Chile. Sweet cherry trees cv. ‘Regina’ and ‘Sweetheart’ were studied to evaluate the effect of foliar application of a biostimulant (Retard Cherry®) prior to leaf fall on the bloom delay, fruit set, fruit drop, yield and quality. Data were compared to a non-product control. The study was conducted in the Maule Region, Chile. Results showed that the use of Retard Cherry® delayed full bloom by 6-8 days between cultivars compared to the control; however, there was no delay in the harvest date. The climatic conditions favored high fruit set (37%-49%) and low fruit drop (63%-70%) between cultivars in both treatments. Regarding fruit quality, no differences in size, soluble solids concentration and color were observed with the product, but a decrease in firmness were observed for ‘Regina’. These results show that Retard Cherry® is an effective tool in delaying bloom, providing trees with more favorable climatic conditions for pollination and fruit set.

Letícia AF: Novo cultivar de ameixeira resultante de uma mutação de Laetitia

Abstract: Letícia AF is a mutation of the plum cultivar Laetitia that confers self-compatibility. This work compared the Letícia AF mutant cultivar with the standard Laetitia regarding fruit set, self-compatibility, yield, and fruit quality traits during four growing seasons. The study was carried out in two plum orchards with the cultivar Letícia AF (orchard 1) and Laetitia plus pollinizers trees (orchard 2) and in an experimental unit with Letícia AF and Laetitia planted side by side. A self-compatibility test was performed on covered branches to prevent pollinating insects from reaching the flowers. Fruit set occurs in covered branches of Letícia AF, whereas it was rare in Laetitia. In commercial orchards, Leticia AF plums yield was higher than that of Laetitia over the years. The results suggest that the oscillation in productivity across the years, mainly due to unfavorable conditions for insect pollination, may be lower in the plum Leticia AF orchard. On the other hand, the requirement for fruit thinning may be greater in Leticia AF. No significant differences were found between the mutant and the standard cultivar regarding fruit quality at harvest and after 30 days of cold storage, indicating the mutation did not alter the fruit characteristics.

VARIABILITY OF ECONOMIC VALUE CHARACTERS IN COMMON VARIETIES OF HAZELNUT IN THE TRANSCARPATHIAN REGION

The frost-free period according to average long-term data lasts 170-180 days. The average date of termination of the last spring and the beginning of the first autumn frosts falls on April 18 and October 16, respectively. The deadlines for the earliest and latest cessation of spring frosts are March 23 and May 12, and the beginning of autumn frosts is September 20 and November 12. Thus, the duration of the frost-free period can vary from 146 to 215 days, which significantly affects the reduction of growth processes or freezing of young shoots and fruit buds. the optimal year for the vegetation period was 2019. The year 2020 was very unfortunate for all fruit crops, because it was accompanied by freezing of all types of buds, which did not contribute to the formation of the crop properly and delayed the formation of first-wave shoots for a decade in both varieties. Observing the severely frozen bushes, they noted the lag in leaf growth and the absence of shoots of the first wave, which means the weak development of earrings, which begin to form in June. This state of development will complicate the pollination of the next crop. The development of female buds was noted on the shoots of the second wave, which should give the expected harvest for 2021 when creating conditions for pollination. It should be noted that on some bushes young shoots did not recover, and very frozen parts dried up by mid-summer. In the future, it is necessary to provide smoking and other methods of insulation to prevent damage from late frosts. According to the amount of precipitation, the experimental field belongs to the zone of sufficient moisture. During the year, precipitation is distributed according to average long-term data, the amount of precipitation that falls in winter is only 17% of the annual amount, in spring and autumn 23% and in summer 37%. Therefore, for effective disclosure of the potential of varieties, drip irrigation was carried out, which makes it possible to increase the return on investment. When laying the fields, we decided on the formation of a bush with three to six productive branches placed in a circle. During the vegetation of the third year, 1-2 one-year shoots are formed for future replacement. After flowering, each bush is carefully inspected, patients are pruned, which are intertwined, which allows you to light well and not be affected by powdery mildew. The condition of the bushes for the third year of the growing season is good according to all expectations from the varietal characteristics. Keywords: hazelnuts, varieties, frost resistance, productivity, diseases

High cross-pollination rate of Greek oregano (O. vulgare ssp. hirtum) with Common oregano (O. vulgare ssp. vulgare) under open field conditions as revealed by microsatellite marker analysis

We studied the mode of pollination in Greek oregano (Origanum vulgare ssp. hirtum) under both controlled and open pollination conditions. When grown indoors without the presence of insects, Greek oregano plants did not develop any seeds, indicating a low level of spontaneous self-pollination. Applying manual self-pollination under the same conditions resulted in only 16 seeds, of which only five were able to germinate. At the same time, a clonally propagated Greek oregano plant of the same genotype produced a rich set of over 300 seeds in open field conditions when the flowers were visited by insects in an area where no other Origanum species were observed. Analysis with SSR markers showed that over 70% of the seeds likely resulted from self-pollination, indicating that insect-mediated pollination is essential for the seed development. We further analyzed the cross-pollination of Greek oregano with Common oregano (O. vulgare ssp. vulgare) in open field conditions where the two subspecies were grown in close proximity. Applying SSR markers, we analyzed 83 plants obtained from seeds of three vegetatively propagated Greek oregano mother plants. Surprisingly, the results showed that all analyzed seedlings resulted from cross-pollination of Greek oregano with Common oregano, indicating that cross-pollination between the two subspecies can completely take over the self-pollination or cross-pollination between the Greek oregano plants. The possible impact of the observed high cross-pollination rate on the genetic origin of seeds of selected Greek oregano lines and varieties, as well as on the genetic diversity and structure of natural populations, is discussed.

Mechanical stimulation of the stigmas triggers switch from female to male phase in the protogynous trap flower of Aristolochia rotunda (Aristolochiaceae)

Floral longevity is a selected trait that shows plasticity, allowing plants to balance resource allocation and reproduction. In dichogamous flowers—in which female and male functions are decoupled in time—the duration of the female phase is expected to vary according to pollination status. We used Aristolochia rotunda as a model to test the hypothesis that the female phase should be shortened following pollen deposition on the stigma, and to identify the signal for phase switching. Aristolochia flowers are protogynous (female phase first) and trap pollinators for several days (trap flowers). The four experimental treatments we applied to flowers, i.e. hand pollination, presence of pollinators with or without pollen load in the flower, and deposition of a nylon thread on the stigma, shortened the female phase to a similar extent, demonstrating that the duration of the female phase depended on the presence of pollinators, independently of whether or not they carried pollen, and that mechanical stimulation of the stigmas was the signal for phase switching. Temperature was also shown to shorten the female stage. This mechanism of post-anthesis floral changes is original because usually such changes are triggered by chemical interactions between pollen and stigmas. We interpret the mechanical signal used in A. rotunda for phase switching to be adaptive when pollinators are limiting, because switching to the male phase even if the trapped pollinator does not bring pollen would ensure fulfilling the flower’s male function.

Climate warming may accelerate apple phenology but lead to divergent dynamics in late-spring frost and poor pollination risks in main apple production regions of China

Frost exposure and poor pollination are great challenges for the cultivation of perennial orchard systems such as apples, whose adaptive capacity to climate impacts is limited. Unfortunately, such climatic risks remained largely unexplored due to the complexity in future climate predictions, uncertainties in apple phenological simulations, and difficulties in quantifications of risks of late-spring frost and poor pollination. Here, focusing on the main apple production Sub-regions I–IV (i.e., the Loess Plateau, the Bohai Bay, the Southwest Cool Highland, and Xinjiang) in China, we used an ensemble of seven phenological models to estimate changes in apple first flowering and fruit-setting. Based on phenological sensitivity window proposed, we evaluated the late-spring frost risk and climatic risk of poor pollination based on two individual indices developed for these two kinds of meteorological risks. The phenology model ensemble was driven by climatic data derived from an ensemble of 27 global climate models (GCMs) from CMIP6 to simulate apple phenology in two periods of 2021 − 2060 (Near Future) and 2061 − 2100 (Far Future) under two climate scenarios of SSP245 and SSP585. Model ensemble could largely improve phenology prediction accuracy. Our results also confirmed the general earlier occurrence of apple phenological stages and the shortening of phenological sensitive windows. The first flowering advanced about 0.19 − 0.32 d∙y-1 and fruit-setting advanced about 0.24 − 0.47 d∙y-1. Although the shortening of phenological sensitivity window might decrease frost frequency in some regions and reduce the general risk of late-spring frost (e.g. in Sub-region II), the increase of frost intensity could offset this kind of alleviation and even exacerbate frost risks in Sub-regions I and IV. Finally, except for Sub-region III and a few sites in Sub-regions I and IV, shifts in climatic risks of poor pollination in spatial contrasts were lower than late-spring frost risk. This highlighted late-spring frosts would be more possibly the reason for apple yield or quality losses than the unfavorable climatic pollination conditions under climate change. Model ensemble provides a realistic assessment for quantifying future risks of late spring frost and poor pollination in apple production systems, and helps to identify urgent meteorological risks and provide options for apple production systems in response to climate change.

Alternative Evolutionary Pathways in Paspalum Involving Allotetraploidy, Sexuality, and Varied Mating Systems.

The genetic systems of Paspalum species have not been extensively studied. We analyzed the ploidy, reproductive mode, mating system, and fertility of four Paspalum species-Paspalum durifolium, Paspalum ionanthum, Paspalum regnellii, and Paspalum urvillei. An analysis of 378 individuals from 20 populations of northeastern Argentina was conducted. All populations of the four Paspalum species were pure tetraploid and had a sexual and stable reproductive mode. However, some populations of P. durifolium and P. ionanthum showed low levels of apospory. Populations of P. durifolium and P. ionanthum had low seed sets under self-pollination but were fertile under open pollination, showing that self-incompatibility likely caused self-sterility. In contrast, populations of P. regnellii or P. urvillei showed no evidence of apospory, and seed sets in both self- and open pollination conditions were high, suggesting that they are self-compatible due to the absence of pollen-pistil molecular incompatibility mechanisms. The evolutionary origin of the four Paspalum species could explain these differences. This study supplies valuable insights into the genetic systems of Paspalum species, which could have implications for their conservation and management.

AN ALGORITHM FOR RESEARCH OF SUNFLOWER HYBRIDS PRODUCTIVITY UNDER CONDITIONS OF INSECT POLLINATION

The article summarizes the practical experience of five-year research on seed productivity of autofertile hybrids of sunflower Helianthus annuus L. in the presence and absence of insect pollination. The productivity of 21 sunflower hybrids from six producers «Pioneer», «Syngenta», «Euralis», «Limagrain», «MAS Seeds», «RAGT» - was studied. Experiments were conducted in the fields of the Continental Farmers Group agro-holding in the agroclimatic conditions of Western Ukraine. To exclude the effect of insect pollination, the heads of experimental plants were covered with bag isolators made of 50x40 cm polypropylene spunbond with a density of 30 g/m2 and the ability to adjust the strength of tying during inflorescence development. The heads of control plants were left open for free insect pollinators access. After full seed maturity, the isolators were removed from the experimental plants, and the heads of control plants were selected based on the identity of their diameters. The selected material was dried to an air-dry state and used for further research in laboratory conditions. Seed productivity was determined by indicators such as incompleteness of heads and seeds in different zones of the head disk, huskiness, 1000-seed weight, purity, biological yield, oil content, and protein content. Individual indicators of hybrid productivity were studied for the head disk within the outer, intermediate, and inner zones, each of which occupied one-third of its radius. To determine the incompleteness of seeds and huskiness in each zone of the head disk, 20 seeds were randomly selected from each zone and cleaned of seed coats. Analysis of oil content and protein content was carried out by a non-invasive method of NIR spectroscopy. The paired Wilcoxon criterion was used to determine statistically significant differences between control and experimental groups of plants under different pollination conditions. As a result of the conducted research, it was possible to develop an algorithm for determining quantitative and qualitative indicators of productivity of modern sunflower hybrids in the presence and absence of insect pollination

Simulated pollinator decline has similar effects on seed production of female and hermaphrodite Lobelia siphilitica, but different effects on selection on floral traits.

Pollinator decline, by reducing seed production, is predicted to strengthen natural selection on floral traits. However, the effect of pollinator decline on gender dimorphic species (such as gynodioecious species, where plants produce female or hermaphrodite flowers) may differ between the sex morphs: if pollinator decline reduces the seed production of females more than hermaphrodites, then it should also have a larger effect on selection on floral traits in females than in hermaphrodites. To simulate pollinator decline, we experimentally reduced pollinator access to female and hermaphrodite Lobelia siphilitica plants. We compared the seed production of plants in the reduced pollination treatment to plants that were exposed to ambient pollination conditions. Within each treatment, we also measured directional selection on four floral traits of females and hermaphrodites. Experimentally reducing pollination decreased seed production of both females and hermaphrodites by ~21%. Reducing pollination also strengthened selection on floral traits, but this effect was not larger in females than in hermaphrodites. Instead, reducing pollination intensified selection for taller inflorescences in hermaphrodites, but did not intensify selection on any floral trait in females. Our results suggest that pollinator decline will not have a larger effect on either seed production or selection on floral traits of female plants. As such, any effect of pollinator decline on seed production may be similar for gender dimorphic and monomorphic species. However, the potential for floral traits of females (and thus of gender dimorphic species) to evolve in response to pollinator decline may be limited.

Oscillating flower colour changes of Causonis japonica (Thunb.) Raf. (Vitaceae) linked to sexual phase changes

Flower colour change may represent an ‘honest signal’ for pollinators, denoting flowers with good conditions for rewards and pollination. All previously reported flower colour changes are unidirectional, except for an incomplete case in one Fabaceae species. In this study, we discovered a very rare example of complete oscillating flower colour change associated with sexual phase changes in Causonis japonica (Vitaceae). More specifically, flower discs of C. japonica exhibit an orange colour in the initial male phase then soon fade into pink with desorption of the stamens. Several hours later in the daytime of the same or the following day, with stigma maturation and style elongation, the orange flower disc colour is recovered before fading into pink again. Importantly, we found that the colour change is caused by the accumulation and the degradation of carotenoids. Moreover, nectar secretion was roughly correlated with the abovementioned colour changes. This is the first example of an apparent oscillating colour change mediated by carotenoid content alteration in flowers.

Research Progress on Efficient Pollination Technology of Crops

Pollination is essential to maintain ecosystem balance and agricultural production. Domesticated bee pollination, which is easy to feed and manage, and mechanized pollination, which is not restricted by the environment, are considered the main technical means to alleviate the “pollinating insect crisis”. By analyzing differences in pollination methods for different crops, this review summarizes the research progress for efficient pollination technology from the perspectives of bee pollination and mechanized pollination in fields, orchards, and greenhouses. The selection of pollination method should be based on the physiological characteristics of crops and the actual environmental conditions of natural pollination. The pollination ability of bees is closely related to the status of the bees. Maintaining the pollination ability of bees in a reasonable range is the goal of bee pollination services. Colony state control technology needs to develop in two directions. First, there is a need to develop colony state monitoring technology based on multi-feature information fusion and to explore the self-regulation mechanisms of the colony in response to various factors. Second, based on these self-regulation mechanisms, there is a need to develop a low-cost and non-invasive bee colony state and pollination capacity estimation model, monitoring technology, and equipment based on single feature information. The goals of mechanized pollination are “efficiency” and “precision”. Mechanized pollination technology needs to be developed in two directions. First, the mechanisms of pollen abscission, transport, and sedimentation in different crops and mechanized pollination conditions should be explored. Second, research and development of efficient and accurate pollination equipment and technology based on the integration of multiple technologies such as pneumatic assistance, auxiliaries, static electricity, target, variables, and navigation, are needed.

Cowpea speed breeding using regulated growth chamber conditions and seeds of oven-dried immature pods potentially accommodates eight generations per year

BackgroundCowpea is a dryland crop with potential to improve food security in sub-Saharan Africa, where it is mostly produced and consumed. Contemporary plant improvement technologies, including genome editing, marker-assisted selection, and optimized transformation protocols, are being deployed to improve cowpea characteristics. Integrating speed breeding with these technologies would accelerate genetic gain in cowpea breeding. There are established speed breeding protocols for other important legumes, such as soybean, peanut, and chickpea, but none has been previously reported for cowpea.ResultsWith the aid of regulated growth conditions in two different chamber types, as well as the cultivation of new plant generations from seeds of oven-dried immature pods, we developed and validated, for the first time, an efficient speed breeding protocol that accommodates approximately seven to eight breeding generations per year for 3 cowpea genotypes. The 3 cowpea genotypes were evaluated under controlled growth conditions in light-emitting diode and metal halide lamp chambers to determine the effect of CO2 supplementation on flowering and maturation durations, optimum conditions for plant growth, cross pollination, and pod development. Elevated CO2 concentration had no influence on either flowering time or pod development. Adequate temperature, relative humidity and light intensity improved plant development and the rate of successful hand pollination, and cultivating seeds of 11-day-old immature pods oven-dried at 39 °C for 2 days resulted in at least a 62% reduction in the time between pollination and sowing of the next plant generation. The plants cultivated from seeds of the oven-dried immature pods showed no defect at any stage of development.ConclusionsUsing the speed breeding protocol developed in this study, cowpea breeding cycles can be increased from the traditional one cycle per year in the field to as many as 8 generations per year in regulated growth chamber conditions. This protocol has no special technical requirements; hence, it can be implemented in any standard growth chamber. This would fast-track development, testing, validation, and utilization of improved cowpea cultivars.

Theoretical study of the accumulation of mechanical mixtures in the engine lubrication system

The work in the field of oil obsolescence, theoretical identification of active additives contained in the oil as a benchmark for evaluating the main operational properties of oil, as well as a theoretical assessment of the properties of oil oxidation resistance and the resource of its active elements, depending on the intensity of the eating of engine details and the amount of elements. The sharply changing climate and high pollination conditions of the republic, a sharp increase in the amount of water and mechanical mixtures, which in turn can lead to a premature departure of motor oils used in it, such as viscosity, corrosion resistance, oxidation resistance, washing and other properties, and acceleration of engine eating. Due to the overload of the tractor, theoretically determined that mechanical mixtures and asphalt products containing oxidation products containing motor oil in the engine maintenance system increased by 1.2%.

Pollinator activity and their role on seed set of medicinal and aromatic Lamiaceae plants

Lamiaceae is one of the most economically important plant families based on their aromatic, medicinal, and industrial significance. In the present study three species of the Lamiaceae subfamily, Nepetoideae (Ocimum basillicum, Nepeta cateria, Leucas aspera) and one species from Lamioideae (Rosmarinus officinalis) were selected to document the pollinator bee diversity, foraging behavior, and their role on seed set. Thirty-two species of bees representing three families of Hymenoptera, (Apidae (94.87%) followed by Megachilidae (3.74%) and Halictidae (1.40%) were observed in all four plant species. Non-Apis bees were more abundant (69.35%) than Apis species (30.65%). The species-level variation in pollinator bees was observed in each plant species irrespective of space, time, and environmental conditions. O. basillicum attracted the maximum number of pollinator species (22) followed by R. officinalis (14) and L. aspera (10) and N. cataria (5). In O. basillicum, Ceratina species were major flower visitors, whereas R. officinalis was mainly visited by both Ceratina and Apis sp. L. aspera was dominated by Amegilla species and N. cataria mostly visited by the Apis bee species. However, irrespective of the diversity, the abundance of pollinator activity mainly contributed to enhancing the maximum number of seeds set in each species up to 64% overall increase under open pollination compared to bagged conditions. Also, a significant reduction in the seed set percentage was observed in R. officinalis and L. aspera under bagged pollination conditions. This indicates the high dependency of Lamiaceae plants on bee pollinators to maintain their reproduction and regeneration activities.