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Elaedobius kamerunicus (EK) is the most effective oil palm pollinator, and has positively improved the rate of pollination and oil yield. However, the decline in the oil palm fruit set and oil yield is alarming in oil palm industries. Therefore, this study investigated the EK population abundance and its impact on the oil palm fruit set. A significant variation in EK population was observed among the biparental families and a decline in its population abundance. The highest mean number of EK per palm was recorded on Day-three and family ECPHP500 recorded the highest (2367.94 ± 140.74). The total population means of EK was 36830.14 ± 851.68 per hectare and ECPHP550 recorded the highest at 52,189.64 weevils per hectare.A simple linear regression and correlation coefficient (r) analysis indicated declines in the efficiency of the weevil and it accounted for 31% of the variation in fruit to bunch, 25% in average bunch weight, 37% infertile fruit, and 33% of the total variation in oil palm fruit set ratio. The oil palm traits analysed, had a positive and highly significant moderate correlation with the weevil effectiveness. A strong perfect relationship was established between Day-three anthesis with EK population per inflorescence (r = 0.99, df = 3, 23, P˂0.0001). Moderate evaporation rate, rainfall, wind velocity, and sunshine duration with temperature (29oC) will increase the weevil population and efficiency. Future research and good management practices should be considered to improve the population and pollination effectiveness of EK, enhancing the livelihoods of farmers.

Improved rice lines were developed frome three parents with the resistance or tolerance to bacterial leaf blight, blast and drought stress, respectively, using single-, double- and three-way crosses. The improved lines were assessed for agro-morphological and yield traits under non-drought stress (NS) and reproductive-stage drought stress (RS) treatments. The mean comparison of traits measured between parent plants and progenies (improved lines) were similar, and there were significant and non-significant differences among the parents and improved lines (genotypes) under NS and RS. Smilarly, there was significant and non-significant differences in the interaction among both parent varieties and improved lines for NS and RS. Cluster and 3D-model of principal component analysis did not generate categorical clusters according to crossing methods, and there were no exclusive crossing method inclined variations under the treatments. The improved lines were high-yielding, disease resistant, and drought-tolerant compared with their parents. All the crossing methods were good for this crop improvement program without preference to any, despite the number of genes introgressed.

This study investigated oil palm inflorescence sex ratio (ISR) and fruit set (FS) yield among 24 dura × pisifera biparental progenies on fibric peat soil, hybridized from ten genetic origins. Three-month intervals of data collection on ISR and “S-shape” procedure for FS determination were carried out in an independent complete randomized design for one year. Based on the assessment of individual progenies, analysis of variance revealed the existence of genetic heterogeneity. Five of the progenies had the highest ISR above 90%. However, 20.83% of the progenies (PK4841, PK4674, ECPHP415, ECPHP550, and PK4118) had the best normal range of ISR, indicating FS declined being influenced by ISR. Therefore, only 12.50% of the progenies (PK4674, PK4465, and PK4482) were above 60% FS critical level. Correlation analysis verified that ISR depends on the female flower and progeny PK4674 (65.78%) and PK4465 (62.62%) had the best FS and fruit to bunch. Among the parental origins, Deli Serdang × Cameroon was statistically the best for male flower production at 29.40% and ISR at 72.22%. The highest FS was recorded in Deli Banting × AVROS (54.00%) and Angola × AVROS (53.78%). However, molecular research, such as microsatellite molecular markers if concurrently used as a selection criterion with the present conventional study, could present further details to complement the present findings.

Marker-assisted selection and gene pyramiding are very important breeding strategies for conferring broad spectrum and durable resistance against diseases causing yield loss in rice. One such disease causing major set backs in rice production is bacterial leaf blight (BLB) caused by the pathogen Xanthomonas oryzae pv. oryzae. Molecular markers are very essential in both marker-assisted selection and pyramiding of genes, hence, many molecular marker techniques have already been developed. Presently, the most commonly used ones are DNA-based markers also known as molecular markers. The molecular markers are classified into two major categories based on the techniques used for detecting them. These are hybridization and polymerase chain reaction-based markers. Other types of markers available include the morphological (traditionally based) and biochemical (enzyme-based) markers. Host plant/varietal resistance is the most suitable means for controlling BLB disease of rice. Marker-assisted gene pyramiding has the potential to accelerate the breeding programmes and guarantee the durability of resistance conferred in the host plant. Therefore, this paper uncovers the utilization, economic importance, limitations and future prospects of marker-assisted selection and gene pyramiding for resistance to BLB disease of rice.

This study was conducted to assess the Elaeidobius kamerunicus (EK) population density among the biparental dura × pisifera hybrids’ palms on deep peat-soil. Twenty-four hybrids derived from 10 genetic sources were used. Variance analysis showed that the EK population density varies between different oil palm hybrids, with a more noticeable variation of a low population mean in the male weevil across the hybrids. The highest weevil population mean/spikelet was attained on the third day of anthesis. The maximum monthly population of EK/spikelet (12.81 ± 0.23) and population density of EK (1846.49 ± 60.69) were recorded in January. Accordingly, 41.67% of the hybrids recorded an EK population density greater than the trial means of 973.68 weevils. Hybrid ECPHP550 had the highest mean of EK/spikelet (10.25 ± 0.11) and the highest population density of EK/palm (1241.39 ± 73.74). The parental mean population was 963.24 weevils and parent Deli-Banting × AVROS recorded the highest EK population density (1173.01). The overall results showed a notable disparity in the EK population among the biparental hybrids. Parental Deli-Banting × AVROS and hybrid ECPHP550 could be more useful to optimize the weevil population for pollination improvements in palm plantations. However, we suggest that volatile production should be included as a desirable trait in oil palm selective breeding.

One of the most important and widely known plantation crops with high revenue returns is the Elaeis guineensis palm. To date, yield variability in fresh fruit bunches (YFFB) in Malaysian oil palm plantations is one of the key influences in low palm oil yield. Accordingly, an assessment of dura×pisifera progenies and their genetic origins on oil palm yield was investigated. Twenty-four derived progenies from 10 genetic sources were adopted as F1 hybrid-single generation and the standard approach for data collection of the yield and yield traits was followed for three sequential years. Variance analysis showed genetic differences between the progenies and their origins. Amid the progenies analyzed, 45.83% had YFFB above the trial mean. Progeny HPDP500 had the highest YFFB (191.74 kg/palm/year) and the highest bunch number (YBNO) was recorded in PKDP4474 (20.65 bunches/palm/year), and HPDP500 (20.53 bunches/palm/year). In year one and year three, the highest YFFB was reported, while in year one of data collection, the highest YBNO was recorded. Dura-Ulu Remis × Yangambi had the highest YFFB (175.81 kg/palm/year) and Tanzania × Nigeria recorded the highest YBNO (19.06 bunches/palm/year). High heritability and phenotypic coefficient of variation with a moderate genotypic coefficient of variation for all the traits were further revealed. YFFB had a moderate positive YBNO relationship (r = 0.676; df =3, 23; p = 0.0001) and a weak positive average bunch weight correlation (r = 0.378; df = 3, 23; p = 0.0001). For tissue culture and hybridization programs for yield enhancement, progenies and origins with better performance may be used; however, the use of molecular research as a selection criterion seems to be worth further analysis.

Simple Summary Elaeidobius kamerunicus is the most efficient pollinator in oil palm plantations. The decline in the oil palm fruit-set and oil yield can be offset with this pollinator weevil. This study measured the population density of E. kamerunicus in biparental dura × pisifera hybrids. The result showed a significant variation in the population density of the weevils among the planting materials. The female population was higher than the male weevil across the hybrids. The highest weevil population was recorded on the third day of anthesis with a decline in its population in subsequent anthesis. The highest mean of E. kamerunicus population per spikelet and its population density per month was recorded in January. Hybrid ECPHP550 had the highest mean of E. kamerunicus per spikelet and its population density per palm. Hybrid ECPHP550 could be used in palm plantations to maximize the weevil population, especially the male weevil because of its pollen carrying capacity; thus, pollination in palm plantations can be improved in achieving good fruit-set and oil yield. Abstract This study was conducted to assess the Elaeidobius kamerunicus (EK) population density among the biparental dura × pisifera hybrids’ palms on deep peat-soil. Twenty-four hybrids derived from 10 genetic sources were used. Variance analysis showed that the EK population density varies between different oil palm hybrids, with a more noticeable variation of a low population mean in the male weevil across the hybrids. The highest weevil population mean/spikelet was attained on the third day of anthesis. The maximum monthly population of EK/spikelet (12.81 ± 0.23) and population density of EK (1846.49 ± 60.69) were recorded in January. Accordingly, 41.67% of the hybrids recorded an EK population density greater than the trial means of 973.68 weevils. Hybrid ECPHP550 had the highest mean of EK/spikelet (10.25 ± 0.11) and the highest population density of EK/palm (1241.39 ± 73.74). The parental mean population was 963.24 weevils and parent Deli-Banting × AVROS recorded the highest EK population density (1173.01). The overall results showed a notable disparity in the EK population among the biparental hybrids. Parental Deli-Banting × AVROS and hybrid ECPHP550 could be more useful to optimize the weevil population for pollination improvements in palm plantations. However, we suggest that volatile production should be included as a desirable trait in oil palm selective breeding.

This research was conducted to study the performance of biparental dura &times, pisifera (D &times, P) progenies and their parental genetic origins on fruit set and yield components. Twenty-four D &times, P progenies developed from 10 genetic origins were used for this study. Analysis of variance showed that there was genetic variability based on the evaluation of individual progenies. Deli Ulu Remis &times, Nigeria of progeny ECPHP500 recorded the highest bunch number (22.91), and fresh fruit bunch (184.62 kg palm&minus, 1 year&minus, 1) and Deli Banting dura &times, AVROS pisifera (ECPHP550) had the highest average bunch weight (10.36 kg palm&minus, 1). Progenies PK4674 (61.12%) and PK4465 (60.93%) had the highest fruit set, and the highest oil yield of 52.66 kg palm&minus, 1 was noticed by progeny PK4674. Estimation of variance components, coefficients of variation, heritability, and genetic gain were calculated to establish the genetic variability. To validate the genetic disparity among the progenies, an unweighted pair-group procedure with arithmetic mean (UPGMA) and principal component was employed based on their quantitative traits. Through the UPGMA and principal component, the 24 progenies were clustered into 7 clusters, whereas cluster V had the highest fruit set (60.62%) and cluster IV had the highest oil yield (43.71 kg palm&minus, 1). For oil palm tissue culture and breeding programs, progeny PK4674 will be more useful for developing planting materials of high oil yielding with stable performance. However, we recommend that future studies incorporate molecular studies with conventional breeding.

Plant breeding, particularly oil palm, takes up to 20 years per cycle for phenotypic selection which is characterized by low planting densities and longer generations. This, however, has numerous consequences such as limited breeding intensity and reduced number of generations that can be reached in between two breeding stages. In the attempt to reconcile the rapid achievement of varietal outputs and the long-term improvement of the tropical tree crops programme, the recurrent selection schemes were adopted. This paper presents an overview of recurrent selection with emphasis on modified reciprocal recurrent selection which is widely used in oil palm. Based on this background, the objectives of this breeding method were highlighted, and some achievements recorded through the method were elaborated.