Female Flower Production Research Articles

Comparative RNA-Seq Analysis between Monoecious and Androecious Plants Reveals Regulatory Mechanisms Controlling Female Flowering in Cucurbita pepo.

In the monoecious Cucurbita pepo, the transition to female flowering is the time at which the plant starts the production of female flowers after an initial male phase of development. Ethylene plays an essential role in this process since some ethylene deficient and ethylene-insensitive mutants are androecious and only produce male flowers. To gain insight into the molecular mechanisms regulating the specification and early development of female flowers, we have compared the transcriptomic changes occurring in the shoot apices of WT and androecious ethylene-insensitive etr1b mutant plants upon female flowering transition. There were 1160 female flowering-specific DEGs identified in WT plants upon female flowering, and 284 of them were found to be modulated by the ethylene-insensitive etr1b mutation. The function of these DEGs indicated that female flower specification depends on the adoption of a transcriptional program that includes previously identified sex-determining genes in the ethylene pathway, but also genes controlling the biosynthesis and signaling pathways of other phytohormones, and those encoding for many different transcription factors. The transcriptomic changes suggested that gibberellins play a negative role in female flowering, while ethylene, auxins, ABA and cytokinins are positive regulators. Transcription factors from 34 families, including NAC, ERF, bHLH, bZIP, MYB and C2H2/CH3, were found to be regulating female flowering in an ethylene-dependent or -independent manner. Our data open a new perspective of the molecular mechanisms that control the specification and development of female flowers in C. pepo.

Optimizing Indoor Hemp Cultivation Efficiency through Differential Day–Night Temperature Treatment

This study was conducted to determine the optimal temperature difference in day–night indoor cultivation conditions to enhance the flower yield and functional component contents of female hemp plants. Hemp clones were cultivated under five distinct day and night temperature differences (DIF) during the reproductive stage. The daytime and nighttime temperature settings were as follows: 18:30 °C (negative 12 DIF), 21:27 °C (negative 6 DIF), 24:24 °C (0 DIF), 27:21 °C (positive 6 DIF), and 30:18 °C (positive 12 DIF). Seven weeks after transplantation, the growth parameters, leaf gas exchange, total phenolic compounds, 2,2-diphenylpicrylhydrazyl scavenging activity, and cannabinoid contents were analyzed. The total shoot biomass based on dry weight was highest at 21:27, reaching 41.76 g, and lowest at 30:18, measuring 24.46 g. However, the flower biomass, which is the primary production site, was highest at 24:24 and lowest at 18:30, showing a 4.7-fold difference. The photosynthesis-related parameters were temperature-dependent and strongly correlated with biomass production. The cannabinoid content of the hemp leaves increased at 21:27, whereas that of the hemp flowers increased at 27:21. The findings of this study indicate that the optimal temperature condition for female hemp flower production in a limited space is positive 6 DIF treatment, which corresponds to 27:21 °C. These results can contribute to advancements in indoor crop cultivation technology.

A point mutation in MC06g1112 encoding FLOWERING LOCUS T decreases the first flower node in bitter gourd (Momordica charantia L.).

In Cucurbitaceae crops, the first flower node (FFN) is an important agronomic trait which can impact the onset of maturity, the production of female flowers, and yield. However, the gene responsible for regulating FFN in bitter gourd is unknown. Here, we used a gynoecious line (S156G) with low FFN as the female parent and a monoecious line (K8-201) with high FFN as the male parent to obtain F1 and F2 generations. Genetic analysis indicated that the low FFN trait was incompletely dominant over the high FFN trait. A major quantitative trait locus (QTL)-Mcffn and four minor effect QTLs-Mcffn1.1, Mcffn1.2, Mcffn1.3, and Mcffn1.4 were detected by whole-genome re-sequencing-based QTL mapping in the S156G×K8-201 F2 population (n=234) cultivated in autumn 2019. The Mcffn locus was further supported by molecular marker-based QTL mapping in three S156G×K8-201 F2 populations planted in autumn 2019 (n=234), autumn 2020 (n=192), and spring 2022 (n=205). Then, the Mcffn locus was fine-mapped into a 77.98-kb physical region on pseudochromosome MC06 using a large S156G×K8-201 F2 population (n=2,402). MC06g1112, which is a homolog of FLOWERING LOCUS T (FT), was considered as the most likely Mcffn candidate gene according to both expression and sequence variation analyses between parental lines. A point mutation (C277T) in MC06g1112, which results in a P93S amino acid mutation between parental lines, may be responsible for decreasing FFN in bitter gourd. Our findings provide a helpful resource for the molecular marker-assisted selective breeding of bitter gourd.

Cannabis sativa: Difference between Medical Cannabis (Maijuana or drug type) and Industrial hemp

This paper reviewed the importance of Cannabis sativa and highlights difference between Medical Cannabis (Maijuana or drug type) and Industrial hemp. Cannabis has been used for thousands of years for recreational, medicinal, or religious purposes. Industrial hemp and marijuana share the same species, Cannabis sativa L, but represent different varieties. As such, there are genetic differences that lead to different chemical characteristics, which, in turn, lead to different uses. Cannabis sativa L., is classified into two types as Industrial Cannabis sativa, hemp or Medical Cannabis sativa L.(drug or marijuana) based on its Λ9-tetrahydrocannabinol (THC), content. Medical Cannabis sativa (drug or marijuana) contains very high levels of Λ9-tetrahydrocannabinol (THC) (above 0.3 to 38% of dry weight) and grown inside the greenhouse controlled conditions for the production of unfertilized female flowers. These female flowers accumulates the psychoactive molecule THC and used for health disorders. On the other hand Industrial Cannabis sativa L. (Hemp) contains very low levels of THC (0 to 0.3% of dry weight) grown outside in a large agriculture farms for the production of fibre, seeds and oil. Hemp is used as a functional food and medicine since it contains Cannabidol (CBD), and very low levels of THC.

Identification of Causal Gene-Specific SNP Markers for the Development of Gynoecious Hybrids in Cucumber (Cucumis sativa L.) Using the PathoLogic Algorithm

Although the genome sequence of cucumber is publicly available, only a limited number of functional markers are in store for developing gynoecious hybrids using Indian genotypes. This study reported novel SNPs and InDels in the exonic regions of genes involved in gynoecy using two parents and their hybrid with genotyping-by-sequencing (GBS) by generating 3.547 Gb of raw data. Using NSDC reference genome GCA_000004075.2, a total of 40,143, 181,008 and 43,612 SNPs were identified, among which 514 were polymorphic between male and female parents but monomorphic between the male parent and the hybrid (confirming hybridity). We further identified that, out of those 514 SNPs, 74 were within the exonic regions of the sex-specific genes. The most interesting functional marker in this study was SNP 2,13,85,488, identified in the gene CsaV3_6G037780 G3I-38214 on chromosome 6, encoding 1-aminocyclopropane-1-carboxylate oxidase 1 (ACS1), which plays a key role in female flower production, as indicated in CuCyc with the PathoLogic algorithm. The InDel analysis also identified a variation inside the gene CsaV3_6G304050 G3I-37940, encoding histone lysine N-methyl transferase, involved in flowering and female gametophyte development. Thus, this study has identified gynoecy-specific functional markers; upon further validation, these markers will accelerate the evolution of gynoecious hybrids in India and global cucumber breeding programs.

Reproduction alternation in trees: testing the resource depletion hypothesis using experimental fruit removal in Quercus ilex.

The keystones of resource budget models to explain mast seeding are that fruit production depletes tree stored resources, which become subsequently limiting to flower production the following year. These two hypotheses have, however, rarely been tested in forest trees. Using a fruit removal experiment, we tested whether preventing fruit development would increase nutrient and carbohydrates storage and modify allocation to reproduction and vegetative growth the following year. We removed all the fruits from nine adult Quercus ilex L. trees shortly after fruit set and compared, with nine control trees, the concentrations of nitrogen (N), phosphorus (P), zinc (Zn), potassium (K) and starch in leaves, twigs and trunk before, during and after the development of female flowers and fruits. The following year, we measured the production of vegetative and reproductive organs as well as their location on the new spring shoots. Fruit removal prevented the depletion of N and Zn in leaves during fruit growth. It also modified the seasonal dynamics in Zn, K and starch in twigs, but had no effect on reserves stored in the trunk. Fruit removal increased the production of female flowers and leaves the following year, and decreased the production of male flowers. Our results show that resource depletion operates differently for male and female flowering, because the timing of organ formation and the positioning of flowers in shoot architecture differ between male and female flowers. Our results suggest that N and Zn availability constrain flower production in Q. ilex, but also that other regulatory pathways might be involved. They strongly encourage further experiments manipulating fruit development over multiple years to describe the causal relationships between variations in resource storage and/or uptake, and male and female flower production in masting species.

Character Association and Path Coefficient Studies in Cucumber (Cucumis sativus L.): Experimental Investigation

Thirty two cucumber genotypes were collected from different states of India and were evaluated for yield and quality characters at Bhubaneswar, Odisha during Rabi season of 2019. The relationships between fruit yield and yield components in cucumber genotypes were investigated and correlation studies revealed that yield per plant had positive and significant association with vine length, number of fruits per plant, fruit length, fruit diameter and average fruit weight, while significant negative correlations were observed with node at which first female flower appears, number of days to first female flower production, days to first harvest and severity of downy mildew percentage both at phenotypic and genotypic levels. Path coefficient analysis revealed that fruit diameter had maximum positive direct effect on yield per plant followed by fruit length, number of fruits per plant, days to first harvest, average fruit weight while, negative direct effect of number of days to first female flower production and severity of downy mildew percentage was observed on yield per plant. Future breeding should focus on selecting the characters having direct effects to improve yield per plant.

Annual variability in the sound acorn production of Quercus serrata is regulated by a seed‐predatory weevil in western Japan

AbstractIn plants, processes from flowering to seed maturation are influenced by various factors, including weather conditions, resource supply, and damage inflicted by seed predators, that collectively contribute to annual variability in seed production. To identify the important factors associated with sound acorn production in Quercus serrata, from 2014 to 2020, we investigated the demographic processes from flowering to acorn maturation in six individual trees within a stand in a warm‐temperate secondary forest in western Japan. We found that the annual production of female flowers was positively correlated with the difference in April temperatures between successive years. However, their fluctuation was low and unaffected by either seed or flower production in the previous year. Compared with those of female flowers, the annual variability in sound acorn production within an individual was significantly higher and more synchronized. Key factor analyses revealed that reproductive losses due to the oviposition and sap‐sucking activities of Mechoris ursulus were the most prominent factors contributing to the observed annual variation in total predispersal losses at an individual level, and their effects were synchronized among individuals within a population. Survival from female flowering to sound acorn maturation was strongly predicted by the temperature in June, which corresponds to the period of adult M. ursulus emergence. Our findings indicate that the damage inflicted by the main seed predator during the predispersal stage can sufficiently regulate the sound acorn production patterns in Q. serrata that appear to resemble masting behavior (the highly variable and synchronized production of acorns within individuals).

English

F1 progenies derived from a set of diallel crosses involving native and 5 elite cucumber varieties were evaluated in a randomized complete block design (RCBD) with three replications to study combining ability for some important agronomic traits. The analysis of variance revealed that the mean squares due to genotypes were significant for the traits studied, indicating wide diversity among the parents. Mean squares for general combining ability (GCA) and specific combining ability (SCA) were significant, implying both additive and non-additive genetic system controlling the studied traits. Significant GCA values were recorded by the native variety (Odukpani) for vegetative traits, fruit girth and average fruit weight. Low GCA values were recorded for days to flowering by the elite varieties, implying they are negative combiners for early flower influx. GCA for number of pistillate flowers and number of fruits per plant were positive and significant for the elite varieties, indicating they could be exploited in cucumber breeding programmes for improved female flower production. The high mean values for vegetative traits and days to flowering of the progenies arising from crosses with Odukpani as the maternal parent appear to suggest cytoplasmic influence in the inheritance of the traits. Key words: Combining ability, Cucumis sativus, cucumber, gene action.

Studies on vegetative and reproductive growth of cucumber under insect proof net house

A study was carried out at CPCT, IARI, New Delhi during kharif 2013-14 to evaluate the vegetative growth and insect-pest incidence on cucumber under insect proof net house. Significantly higher vine length (94.94 and 178.67 respectively) and number of leaf nod (17.74 and 26.45 respectively) at 30 and 45 days after transplanting, were recorded in seed parent and pollen parent under insect proof net house in comparison to open field. Time taken to opening of first female and male flower in seed parent and pollen parent (39.0 and 34.90 respectively) was significantly lower under insect proof net house. Production of female and male flowers (36.57 and 25.42) was significantly higher under insect proof net house compared to open field crop. Fruit set and matured fruit (5.71 and 2.52) per plant was significantly higher under insect proof net house than open field (2.84 and 1.65 respectively). Incidence of cucumber mosaic virus was negligible under insect proof net house (0%) as compared to open field conditions (56.86%). Therefore, it can be concluded that for growing virus free seed crop and attaining better fruit growth, flowering, fruit setting and mature fruit per plant, hybrid seed production of cucumber should be undertaken in insect proof net house.

Effect of different plant growth regulators on growth, yield and quality parameters of cucumber (Cucumis sativus L.) cv. Kalyanpur green

An investigation was carried out at the Vegetable Research farm, Chandra Shekhar Azad University of Agriculture and Technology, Kanpur during Kharif season of 2018. The soil of the experimental field was sandy-loam with uniform topography. The experiment was laid out in a randomized block design replicated thrice with nine treatments i.e. T1 - foliar application of GA3 (100ppm) at 15 days after sowing, T2 - foliar application of GA3 (150ppm) at 30days after sowing, T3 - foliar application of GA3 (200ppm) at 45days after sowing, T4 - foliar application of NAA (100ppm) at 15days after sowing, T5 - foliar application of NAA (150ppm) at 30days after sowing, T6 - foliar application of NAA (200ppm) at 45 days after sowing, T7 - foliar application of Ethrel (200ppm) at 2-4 leaf stage, T8 - foliar application of Ethrel (300ppm) at pre flowering and T9 - Control (Water Spray). The result shows that an application of Ethrel 200ppm was found most effective in reducing the number of male flowers (90.75) in comparison to female flowers (52.08). GA3 200ppm reduce the number of days required for appearance of first flower (36.58 days) of cucumber plant, increased the production of female flowers (50.25), lowered the male and female sex ratio (1.70: 1), increased number of fruits per plant (11.67), increased yield per plant (3.89 kg) and per hectare (180.69 q). The next best treatment was GA3 100 ppm which increased the yield of fruits per plant (3.42 kg) and yield per hectare. From the results of this investigation, it could be inferred that Ethrel 200 ppm treatment was found most effective in improving femaleness with increased fruit yield of cucumber cv. Kalyanpur Green'. Results revealed that the application of plant growth regulators significantly increased growth. GA3 (100ppm) play an important role in increasing yield characters followed by NAA (100 ppm) and male and female flower ratio can be lowered by the application Ethrel (300 ppm). The fruit set and fruit retention percentage was improved through the application GA3 (150ppm) followed by GA3 (200ppm).

Changes of Morphological and Biochemical Properties in Organically Grown Zucchini Squash (Cucurbita pepo L.)

The present research was undertaken with the aim of justifying the effect of morphological, physiological, and nutritional properties in organically produced zucchini squash. The experiment consisted of two factors: three levels of pruning (P0 = no pruning, P1 = primary pruning at 20 days after transplanting (DAT), and P2 = secondary pruning at 30 DAT) and four levels of vermicompost application (V0 = control, V1 = 5 t/ha, V2 = 10 t/ha, and V3 = 15 t/ha). The results demonstrated that morphological parameters, reproductive components, and yield and proximate compositions were significant differences among the treatments. Increased male and female flower production were recorded from primary pruning with 10 t/ha vermicompost treatment plots compared with control treatments. Finally, increased fruit number, individual fruit weight, fruit length, fruit diameter, total yield, carbohydrate, protein, crude fat, fiber, and ash were reported from the same treatment combination (P1V2). Taken together, 10 t/ha vermicompost with primary pruning appear to provide maximum output in terms of yield and nutrient value compared with other treatments.

Diversity matters: Effects of density compensation in pollination service during rainfall shift.

Extreme weather events are increasing in frequency due to the warming climate. Such extremities can jeopardize ecosystem services and create economic imbalances. Tropical developing countries are predicted to suffer the maximum consequences of such events.We examined the impact of such an event—extreme rainfall fluctuation—on a critical ecosystem service—pollination, which can be intricately linked to a country's economy. We performed this study in a dominant peri‐urban vegetable hub of an agriculture‐dependent developing country.We found that the yield of all pollinator‐dependent crops grown across a large spatial scale (district) over multiple years (six) drastically declined with the decrease in rainfall.At the local scale, we found that the dominant crop (representative horticultural crop) had a significant drop in yield during drought, likely due to the production of fewer female flowers and a significant shift in the pollinator community.We found that Trigona sp. (one of the four pollinators) was the critical pollinator positively influencing fruit‐to‐flower ratio (FFR) (an indicator of pollination service) in the normal rainfall year. However, despite its sharp decline during drought, the FFR remained unaffected. We found that during drought, Apis dorsata was crucial in maintaining FFR and compensated for the decline of the critical pollinator across 67% farmlands.Our study demonstrates the role of ecosystem stabilizing mechanism rescuing the crucial ecosystem service during climatic variability over the temporal scale.

Male-skewed sex ratio in Myrica esculenta: a dioecious tree species

The population of M. esculenta tends to deviate from the equilibrium of expected 1:1 primary sex ratio predicted by Fisherian theory. Populations of dioecious plants may often exhibit biased sex ratios, which generally favour males. A study on reproductive potential, i.e., pollen production and female flower production, and reproductive success in Myricaesculenta was assessed in three diameter (diameter at breast height: dbh at 1.37 m) classes, i.e., small (10–20 cm), medium (20–30 cm), and large (30–40 cm). Population structure and sex ratio was determined in transects in four major associations of Myricaesculenta, i.e., (i) with mixed Oak-Rhododendron forest (ii) with Chir Pine–Oak forest, (iii) with pure Oak forest, and (iv) with pure Deodar forest. The sex ratio of trees was male-biased. Male frequency was higher in lower diameter classes and maximum on resource-poor site. More female individuals were recorded in higher-diameter classes and resource rich location, indicating that the total reproductive cost in M. esculenta is greater in female trees than that of the male trees. The population of M.esculenta tends to deviate from the equilibrium of expected 1:1 primary sex ratio predicted by Fisherian theory. The male trees demonstrated greater survival, especially in resource-poor conditions, which was reflected strongly biased sex ratios within the lower size classes. The study would be helpful for formulating appropriate silvicultural and genetic management strategies for this species.

Evapotranspiration and water response function of squash cv. ‘Italiana’ under different cultivation conditions

ABSTRACT Aiming to support projects and managements of irrigation for vegetables in the Mid-North region of Mato Grosso state, Brazil, this paper determined crop evapotranspiration (ETc), crop coefficients (Kc) and water response function of summer squash (Curcubita pepo) cv. ‘Italiana’ under different cultivation conditions. The plantations were conducted in the dry season of the region (July to October 2016), using 2.5 kg m-2 of millet straw (grass) and crotalaria straw (legume) and bare soil. ETc was obtained by soil water balance through tensiometry, whereas Kc values were given by the ratio between ETc and the reference evapotranspiration (ETo) obtained by the FAO-56 Penman-Monteith method. For the water response function, the rates of 40, 60, 80, 100 and 120% ETc were applied, in which case the Class A pan method was used to obtain ETo. The different soil covers did not influence the ETc, Kc and accumulated thermal sum in the phenological stages of the summer squash. Kc values were 0.1, 0.25, 0.38 and 0.41, for the phenological stages I to IV, with average durations of 8, 46, 16, and 20 days, respectively. Increase in irrigation depths did not influence the rates of production of male and female flowers, but affected yield and decreased water use efficiency, regardless of soil cover.

Drivers of tree fecundity in pedunculate oak (Quercus robur) refugial populations at the species' southwestern range margin.

The current low latitudinal range margins of many extra-tropical plant species consist of small and scattered populations that persist locally in microrefugia. It remains poorly understood how their refugial distribution affects mating patterns and reproductive success. Here we examine flower and acorn production and their determinants in refugial populations of the widespread European forest tree pedunculate oak (Quercus robur). We monitored male flower, female flower and acorn production in 159 adult trees from 12 oak stands over 2years. We related these and derived parameters to a series of ecological and genetic predictor variables extrinsic (stand size, density and isolation as well as elevation, topography and forest cover) or intrinsic (size, phenology and several genotypic measures) to the target tree. Tree fertility was unrelated to extrinsic factors but determined by tree size, although we detected size-independent variation in reproductive investment. Female flower number accurately predicted acorn crop size. Fruit set differed between years, evidencing the existence of pollen limitation at the landscape but not at the local scale. Fruit setalso tended to increase with the number of mates of the target tree. We detected no other evidence for genetic constraints on mating. Reproduction was triggered by a combination of small-scale and landscape-scale drivers. Although short-distance mating prevailed, limited pollen flow did not appear to significantly constrain reproductive success. The high intrinsic ability of populations to maintain their reproductive capacity may help explain their successful long-term persistence in an adverse broader environment.

Flexibility of resource allocation in a hermaphroditic-gynomonoecious herb through deployment of female and male resources in perfect flowers.

It has been hypothesized that two flower types permit flexible allocation of resources to female and male functions, yet empirical evidence for the sex-allocation hypothesis remains scarce in gynomonoecious species. To characterize resource allocation to pistillate and perfect flowers and allocation of perfect flowers between gynomonoecious and hermaphroditic individuals, we examined the flexibility and whether female-biased allocation increases with plant size in the hermaphroditic-gynomonoecious herb Eremurus anisopterus. Frequency of gynomonoecious individuals, flower production, and plant size were investigated in different populations. Floral allocation was compared among the three flower types of E. anisopterus. Frequency of gynomonoecious plants varied from 2-17% in nine populations. Only larger plants produced female flowers at the bottom of racemes. Both female and perfect flower production tended to increase proportionately with plant size in gynomonoecious individuals. Female flowers did not produce less biomass than perfect flowers from hermaphroditic or gynomonoecious plants. However, both female and perfect flowers from gynomonoecious individuals had lighter stamen mass, but larger pistil mass, than perfect flowers from hermaphrodites. Although the prediction of an increase in female flower number with plant size was not observed in E. anisopterus, the flexibility of sex allocation in gynomonoecious species was confirmed in that gynomonoecious individuals had a female-biased floral allocation compared to hermaphroditic individuals. Such comparisons of gynomonoecious to hermaphroditic individuals permit us to unveil a sexual adjustment strategy: flexibility of sexual investments within plants.

Epigenetic Regulation of the Sex Determination Gene MeGI in Polyploid Persimmon.

Epigenetic regulation can add a flexible layer to genetic variation, potentially enabling long-term but reversible cis-regulatory changes to an allele while maintaining its DNA sequence. Here, we present a case in which alternative epigenetic states lead to reversible sex determination in the hexaploid persimmon Diospyros kaki Previously, we elucidated the molecular mechanism of sex determination in diploid persimmon and demonstrated the action of a Y-encoded sex determinant pseudogene called OGI, which produces small RNAs targeting the autosomal gene MeGI, resulting in separate male and female individuals (dioecy). We contrast these findings with the discovery, in hexaploid persimmon, of an additional layer of regulation in the form of DNA methylation of the MeGI promoter associated with the production of both male and female flowers in genetically male trees. Consistent with this model, developing male buds exhibited higher methylation levels across the MeGI promoter than developing female flowers from either monoecious or female trees. Additionally, a DNA methylation inhibitor induced developing male buds to form feminized flowers. Concurrently, in Y-chromosome-carrying trees, the expression of OGI is silenced by the presence of a SINE (short interspersed nuclear element)-like insertion in the OGI promoter. Our findings provide an example of an adaptive scenario involving epigenetic plasticity.

Female fruit production depends on female flower production and crown size rather than male density in a continuous population of a tropical dioecious tree (Virola surinamensis).

Factors related to pollen and resource limitation were evaluated to predict female fruit production in a tropical dioecious tree. Pollen limitation via variation in the male density at local scales is expected to limit female reproduction success in dioecious plants. We modeled the roles of local male density, female crown size, crown illumination, and female flower production on female fruit initiation and mature fruit production in a continuous population (62 ha plot) of a tropical dioecious tree (Virola surinamensis). In addition, we used microsatellites to describe the scale of effective pollen flow, the male effective population size, and the spatial genetic structure within/between progenies and males. The local male density was not related to female fruit initiation or mature fruit production. Female floral production had a positive effect on fruit initiation. The female crown size was positively related to fruit maturation. Seeds from the same female and seeds from different but spatially proximal females were generally half-siblings; however, proximal females showed greater variation. Proximal male-female adult pairs were not significantly more genetically related than distant pairs. The probability of paternity was negatively affected by the distance between seeds and males; most effective pollen dispersal events (∼85%) occurred from males located less than 150 m from females. The number of males siring progenies was greater than the number of males found at local scales. Female fecundity in this continuous population of Virola surinamensis is not limited by the availability of pollen from proximal males. Rather, resource allocation to floral production may ultimately determine female reproductive success.

In vitroevaluation for stability of male sterility in various genotypes, F1and backcross generations with gene action in ridge gourd

In vitro multiplication of elite clones is an attractive approach in order to meet the requirement of quality propagules at large scale for commercial cultivation. In vitro maintenance is effective in maintaining the male sterile line. Standardized protocol was followed for in vitro maintenance of male sterile line. Ridge gourd genotypes were collected from different parts of the country and evaluated for variability with respect to fourteen traits. Sterility was assessed on the basis of pollen fertility percentage, which was found to be zero throughout the flowering season. There was no observable difference with respect to vegetative growth or production of female flowers between male sterile and fertile plants. In vitro regenerated plants exhibited stable male sterility all round the flowering season. Pollen fertility was found to be zero in all the male sterile plants. As compared to back crosses, three way crosses expressed early emergence of first male flower. F2 data indicated cytoplasmic genetic male sterility with more than one gene involved in fertility restoration. Male sterile plants can be used for commercial seed production in vegetable crops with less cost of cultivation.