Number Of Male Inflorescences Research Articles

Effects of Perennial Intercrops on Oil Palm Agronomic and Yield Traits

Background: Intercropping is wildly practiced in oil palm plantation in Thailand for a long time. However, there are few studies connected to oil palm intercropping. This study evaluated the effects of perennial intercrops on the agronomic and yield traits of oil palm.Methods: The observation used a completely randomized design with eight treatments including oil palm monocropping, oil palm intercropped with Intsia palembanica, Hopea odorata, Swietenia macrophylla, Ternstroemia wallichiana, Azardirachta excelsa, Magnolia champaca and Mesua ferrea. The height and stem perimeter of intercrops were recorded as were the plant height and diameter, number of male and female inflorescences and sex ratio of the oil palms. Those parameters were observed in October 2019, February and June 2020.Result: Oil palm intercropped with A. excelsa produced the highest number of female inflorescences and oil palm intercropped with M. champaca produced the highest sex ratio in October 2019 and February 2020, however, the differences of those parameters were not found in June 2020. There were no significant differences in the diameter, height, the number of male inflorescences throughout the observation. Among the 7 intercrops, M. champaca and A. excelsa produced the highest growth rate of plant height and stem perimeter, respectively. In conclusion, oil palm can be intercropped with perennial plants. However, more research is needed to determine the long-term effects of intercropping in oil palm.

Effects of Rainfall, Number of Male Inflorescences and Spikelets on the Population Abundance of Elaeidobius kamerunicus (Coleoptera: Curculionidae)

Elaeidobius kamerunicus was first introduced to Malaysia from Cameroon as an oil palm pollinator in 1981. Since then, oil palm pollination has improved and the need for assisted pollination has reduced. Fruit set development and fruit production also saw significant improvements, until a reported decline that began in the late 1980s. Several factors may have contributed to such decline, but most researchers believe it is due to the low E. kamerunicus population. Therefore, a study was conducted to determine whether the amount of rainfall and the number of male inflorescences and spikelets influenced the population abundance of E. kamerunicus in Ladang Lekir, Perak, Malaysia. Sampling was performed each month in oil palm subplots, three for each age of palm age, from October 2015 to September 2016. A total of nine spikelets (three from the top, middle and base of a male inflorescence) were randomly selected from each male inflorescence on each chosen palm. They were cut early in the morning to avoid the weevil’s most active time, thus making collection easier. The number of weevils congregating on each spikelet was then counted. The average number of E. kamerunicus per hectare (ha) living on oil palms aged four and six were 21,086 and 25,712, respectively. The amount of rainfall and the number of male inflorescences and spikelets were found to positively correlate with the E. kamerunicus population. The number of male inflorescences showed strong correlation with the E. kamerunicus population. However, in-depth study is needed to determine the relationship between E. kamerunicus and fruit set.

Relationships Between Inflorescences and Pollinators and Their Effects on Bunch Components in Elaeis guineensis, in Colombia

Abstract The oil palm, Elaeis guineensis Jacquin, is an allogamous and monoecious plant that is mainly pollinated by insects such as Mystrops costaricensis Gillogly (Coleoptera: Nitidulidae) and Elaeidobius kamerunicus Faust (Coleoptera: Curculionidae). To determine the relationship between inflorescences and pollinators as well as the relationship between pollinators and bunch components, 858 palms, divided equally between two plots planting with cultivars tenera and dura of E. guineensis, were monitored every 2 weeks over 1 yr. Male inflorescences (MIs) and female inflorescences (FIs) at anthesis, and pollinators collected from the inflorescences, were recorded at each sampling. Bunch components and the amount of rainfall during the study period also were recorded. Data were analyzed using Spearman correlations and linear regression. Significant positive correlations of the total number of MIs with the total number of pollinators were found in both cultivars (ρ = 0.72, P < 0.0001, n = 24 in cultivar te...

Effect of indigenous aphids on the development of invasive common ragweed,Ambrosia artemisiifolia(L.) in Hungary

The common ragweed, Ambrosia artemisiifolia (L.), is a widespread invasive weed species in Europe. In order to estimate the hampering effect of native arthropods on the invasive ragweed, the effect of three indigenous aphid species on plant development and pollen production was studied. Common ragweed plants grown in a greenhouse were artificially infested with five apterous individuals of either Aphis fabae Scopoli, Brachycaudus helichrysi (Kaltenbach) or Myzus persicae (Sulzer) at the 4-leaf stage. Feeding by all three aphid species over a five-week period significantly reduced plant height, the number of male inflorescences, the length of racemes, pollen emission and plant dry weight. Brachycaudus helichrysi produced the largest colonies, followed by A. fabae and M. persicae. In a field experiment, the growth rate of A. fabae on caged ragweed plants was similar to that in the greenhouse, but the final numbers of B. helichrysi and M. persicae after 30 days was ten and seven times lower, respectively tha...

Impact of indigenous aphids on development of the invasive common ragweed (Ambrosia artemisiifolia L.) in Hungary

The common ragweed, Ambrosia artemisiifolia is a widespread invasive weed species in Europe. In order to estimate the deteriorative effect of native arthropods on the invasive ragweed the effect of three indigenous aphid species on plant development and pollen production was studied. Common ragweed plants grown in a greenhouse were artificially infested with five apterous individuals of either Aphis fabae, Brachycaudus helichrysi or Myzus persicae at the 4-leaf stage. Feeding by all three aphid species over a 5-week period significantly reduced plant height, the number of male inflorescences, the length of racemes, pollen emission and plant dry mass. Brachycaudus helichrysi produced the largest colonies, followed by A. fabae and M. persicae. In a host plant choice test, B. helichrysi showed significant preference for ragweed over sunflower, whereas A. fabae preferred sunflower and M. persicae did not show any preference. In a field experiment, the growth rate of A. fabae on caged ragweed plants was similar to that in the greenhouse, but the final numbers of B. helichrysi and M. persicae after 30 days was ten and seven times lower than under greenhouse conditions, respectively. On exposed field plants, B. helichrysi was more abundant than other species. However, no aphid species affected the height or dry mass of either caged or exposed plants during a 30-day period. Under controlled conditions aphids effectively hampered development and pollen production of ragweed, however, under Hungarian field conditions the development of ragweed was much more dynamic, therefore no deleterious effect of aphid feeding occurred.

Influência da abertura de trilhas antrópicas e clareiras naturais na fenologia reprodutiva de Gymnanthes concolor (Spreng.) Müll. Arg. (Euphorbiaceae)

In the interior of a seasonal semideciduous forest at Santa Maria, RS, Brazil, we investigated whether a wide and lighter trail differed from a narrow and darker path (darker trail) concerning the reproductive phenology of G. concolor. We also examined whether the creation of natural gaps in 2002 affected the incident light and phenology of G. concolor in 2003, answering the questions: (a) Do the trails differ regarding the incident light on the tree canopy and the number of male inflorescences, female flowers, fruits and fruit size (phenological variables)? (b) Is there a relationship between incident light on the tree canopy and the phenological variables? (c) In each trail, do individuals adjacent to gaps differ from individuals far away from gaps regarding the interannual variation in the incident light and phenological variables? In 2002, the incident light was significantly higher on lighter trail than darker trail trees, but trails did not differ in respect to phenological variables. In 2003, incident light and phenological variables did not differ significantly between trees in lighter trail and darker trail. Therefore, the light incidence on lighter trail did not promote a significantly phenological change. The result is supported by the low number of significant regressions between light incidence and phenological variables. Trees adjacent to gaps presented a light incidence variation significantly higher than those trees far away from gaps, but did not differ in respect to interannual variation in phenological variables. Hence, the higher light incidence after the creation of gaps did not affect significantly the phenology of G. concolor as well, which may need even higher amounts of light to respond to gaps or open trails. Our results may give some insight to the design of ecological trails or other open spaces on natural reserves, to reduce its impact on flowering and fruiting production of the species nearby.

In Vitro Modification of Sex Expression in Mulberry (Morus Alba) by Ethrel and Silver Nitrate

Mulberry (Morus alba L.) is a dioecious plant. In vitro sex modification in mulberry by using two chemicals, viz., ethrel and silver nitrate, is described. 2-Chloroethylphosphonic acid (ethrel) and silver nitrate were filter sterilized and added to Murashige and Skoog (1962) medium supplemented with 5 µM 6-benzyl amino purine (BA). Ethrel applied at different concentrations produced female, male and mixed inflorescences in male mulberry nodal cuttings. Maximum 13.6% female inflorescences were observed on media containing 2000 µg l−1 ethrel. The induction of male, female and mixed inflorescences was observed in female plants after applying silver nitrate to the culture medium. The number of male inflorescences increased with the silver nitrate concentration to a maximum of 22.4% induction on 2500 µg l−1. Bisexual flowers were also observed along with male and female flowers in silver nitrate treated plants.

Experimental results about Platanus pollen deposition

A comparison between the aerobiological and floristic data carried out for Platanus are reported. The source was constituted by 60 Platanus trees. When they were pollinating we calculated the total pollen prodution of the source, controlling the number of male inflorescences for each plant, the number of anthers for each inflorescence and the number of pollen for each anther. Aerobiological data were obtained with 16 Durham gravimetric samplers positioned over an area of approximately 25 km2 at variable distances and in different directions to capture pollen transported by winds coming from any direction.

Floral sex ratios in scrub oak (Quercus ilicifolia) vary with microtopography and stem height

We measured floral sex ratios (number of male inflorescences:number of female flowers) and height of stems (= ramets) of monoecious scrub oak (Quercus ilicifolia) growing along a topographic gradient on the slope of a 20 m deep depression. Stems lower in the gradient experienced increasingly severe conditions in terms of a shorter growing season and a higher incidence of killing frosts. At the top of the gradient, floral sex ratios of tall stems were male biased; however, sex allocation patterns at the bottom showed no such size-dependent relationship. With decreasing elevation (greater stress), the production of male flowers declined more rapidly than that of female flowers. Tall stems reduced overall resource allocation to flower production proportionately more with decreasing elevation than did short stems, but this reduction was again more marked in the male flowering function than in the female. These differential patterns of sex investment explain, at least in part, the variation in size-related gender relationships along this gradient. The more stressful environmental conditions prevailing at the bottom of the depression and the relative costs of the male and prezygotic female function may combine to produce these flowering patterns.

Observations on Natural Pollination in Commercial Plantings of Oil Palm (Elaeis Guineensis) in Malaya

SummaryMost oil palm pollen is produced by male inflorescences 2–3 days after anthesis, and this pollen is the most viable. When protected, pollen viability on female inflorescences is good up to 6 days, after which it declines. The majority of the pollen remains below the canopy, especially at bunch level. Results of quantitative evaluation of pollen dispersal showed that atmospheric pollen density is very variable and is governed by numerous factors. There is a marked diurnal variation, with highest pollen density during the afternoon and a negligible amount during the night and early morning. Rain causes an immediate drop in concentration, but pollen densities were influenced more by the number of days on which rain was recorded than by total rainfall. A relationship exists between pollen density, the number of male inflorescences in the vicinity, and rainfall, but the effects of relative humidity, sunshine and wind are obscure. Whilst pollen density drops rapidly within a short distance from the inflorescence, there is a significant dispersal over greater distances than previously thought.