Effects of Albizia saman (Jacq. Mull) leaf mulch on vegetative growth of maize (Zea mays L.) and soil chemical properties through biomass transfer

The study presents the effects of Albizia saman (Jacq. Mull) leaves in a biomass transfer as a source of organic fertilizer on the soil chemical properties and vegetative growth of maize (Zea mays) compared with NPK (15-15-15) in greenhouse condition. Albizia saman leaves and NPK (15-15-15) were applied at the rate of 2.5, 5.0 and 7.5 t/ha or 60, 90 and 120 kg/ha respectively, separately or in combination. The findings revealed that application of 2.5 t/ha A. saman leaves produced the maximum values for mean leaf number, leaf area and stem height (7.77, 212.24 cm2 and 49.67 cm, respectively) among the leaf much treatments but were not significantly different from those obtained by applying 90 kg/ha NPK fertilizer (7.86, 225.55 cm2 and 48.78 cm, respectively). However, the maximum number of leaf (8.4), leaf area (240.5 cm2), plant height (54.64 cm) and biomass (16.17 g) were obtained from the combination of 2.5 t/ha leaves with 90 kg/ha NPK. There was significant improvement in the soil chemical status with the application of 2.5 or 5.0 t/ha A. saman leaves whereas the application of 5.0 t/ha A. saman leaves experienced the highest value for organic carbon (3.56%), total nitrogen (0.23%) and potassium (0.16 mg/kg) and 2.5 t/ha leaves gave the highest value for available phosphorus (22.30 mg/kg). It can, therefore, be inferred that the application of 2.5 t/ha A. saman leaves as source of organic fertilizer will give a better growth of maize and the combination of this quantity with 90 kg/ha of NPK would give better results in crop yield and maintenance of soil fertility

Bacterial leaf blight resistance in rice: a review of conventional breeding to molecular approach

Breeding for disease resistant varieties remains very effective and economical in controlling the bacterial leaf blight (BLB) of rice. Breeders have played a major role in developing resistant rice varieties against the BLB infection which has been adjudged to be a major disease causing significant yield reduction in rice. It would be difficult to select rice crops with multiple genes of resistance using the conventional approach alone. This is due to masking effect of genes including epistasis. In addition, conventional breeding takes a lot of time before a gene of interest can be introgressed. Linkage drag is also a major challenge in conventional approach. Molecular breeding involving markers has facilitated the characterization and introgression of BLB disease resistance genes. Biotechnology has brought another innovation in form of genetic engineering (transgenesis) of rice. Although, molecular breeding cannot be taken as a substitute for conventional breeding, molecular approach for combating BLB disease in rice is worthwhile given the demand for increased production of rice in a fast growing population of our society. This present article highlights the recent progress from conventional to molecular approach in breeding for BLB disease resistant rice varieties

Genetic variability analysis and selection of pisifera palms for commercial production of high yielding and dwarf oil palm planting materials

This study was carried out to evaluate the performance of pisifera (male parent) palms, their general combining ability, and to identify suitable pisifera palms for large scale production of oil palm planting materials. Twenty-four (24) Deli dura palms were nested into 10 Nigerian pisifera male parent palms to produce 1056 tenera (D × P) palms. Tenera palms were planted in two replicates with 16 palms/progeny/replicate. Data collection on yield and yield component traits carried out consecutively for six years. Analysis of variance (ANOVA) followed by the mean comparison and general combining ability were carried out. These were done to know the performance of each of the pisifera parent palms. Additionally, multivariate analysis in form of cluster analysis was done using the quantitative traits. ANOVA showed significant variability among the pisifera palms based on the traits. Fresh fruit bunch (FFB) of each pisifera palm ranged from 173.80 to 211.46 kg/palm/year (kg/p/yr) with a trial mean of 191.92 kg/p/yr, while the oil yield (OY) ranged from 60.24 to 44.06 kg/p/yr with a trial mean of 53.72 kg/p/yr. Based on their mean comparison and the general combining ability, four palms (P01, P03, P09 and P06) have been ranked to be high yielding and good general combiner for FFB and oil yield. While palm P04, P06 and P09 were found to be good combiners for palm height. From these result, four pisifera palms (P01, P03, P09 and P06) have been identified to be high yielding (in terms of FFB and OY), dwarf height and suitable as pollen sources for commercial production of D × P planting materials

Development of fusarium wilt resistant and high yielding watermelon (Citrullus lanatus L.) variety through marker- assisted backcross breeding

One of the major production limiting diseases of watermelon (Citrullus lanatus L.) is Fusarium wilt (FW) caused by Fusarium oxysporum f. sp. niveum (FON). The use of disease-free cultivars is the preferred method of controlling the disease in a sustainable way. Watermelon is a major crop in Malaysia and the country spends about RM 10 million annually for the importation of its seeds to support local production. There is therefore the need to save this huge amount by breeding for local varieties that will be high yielding and Fusarium wilt resistant. In this study, the Fusarium wilt resistant inbred line CS-19 and susceptible inbred line BL-14 were crossed to generate the F1 population. The subsequent two backcrosses and selfing led to the transfer of the resistance gene (fo-1) into the susceptible inbred line BL-14 using marker-assisted backcrossing (MABC) and the subsequent development of Fusarium wilt resistant lines that still retain the desirable qualities in BL-14. Eleven microsatellite markers linked to the Fusarium wilt resistance gene were selected and two of the markers, BVWS02309 and BVWS01133 located on chromosomes 1 and 9 respectively were used for the confirmation of Fusarium wilt resistant gene in F1,BC1F1, BC2F1 and BC2F2 generations. From the 380 microsatellites markers screened, 78 were found polymorphic between the parents and used for recurrent parent genome (RPG) recovery in each backcross population. From the inheritance test conducted in BC2F1 and BC2F2 generations, the recurrent parent BL-14 scored 4.5 of the 0-5 scale, and this confirmed its susceptibility to the Fusarium wilt disease. In the BC2F1 generation, 72 of the 150 plants showed resistance while 78 plants showed susceptibility when inoculated with the virulent Fusarium oxysporumniveum isolate. Chi-square test (χ2) showed that the observed frequencies in the BC2F1 population fitted into the single gene model. The goodness of fit (p=0.46) to the expected test segregation ratio (1:1) indicated that the resistance is controlled by a single dominant gene. The plants resistant to the Fusarium oxysporum niveum isolate from BC2F1 population showed good fit with the two markers BVWS02309 (χ2= 0.24; p= 0.6892) and BVWS01133 (χ2= 0.11; p= 0.8065), with expected segregation ratio (1:1) for single gene model. These two markers were found suitable for marker-assisted selection of fo-1 gene against Fusarium wilt disease. The BC2F2 population phenotypically segregated into 3:1 ratio (resistant: susceptible). The genotypic segregation of the BC2F2 population using the two markers was in the ratio 1:2:1. This is a confirmation of the fact that resistance to Fusarium wilt disease in CS-19 is under the control of a single dominant gene. The RPG recovery analysis for the best improved lines ranged from 74.7 to 94.4% in BC1F1, 86.8 to 96.8% in BC2F1 and 95.1 to 96.9% in BC2F2 generations. The 96.14% average proportion of the recurrent parent genome in selected improved lines showed the close phenotypic resemblance to the recurrent parent BL-14. Ten homozygous lines carrying Fusarium wilt resistance gene with similar genome background to BL-14 were selected as the developed improved Fusarium wilt resistant breeding lines. The agro-morphological traits showed that there was no significant difference between the recurrent parent BL-14 and Fusarium wilt resistant improved lines developed. In conclusion, this study confirmed that Fusarium wilt resistance inbred line CS-19 is under the control of a single dominant gene and it is linked with SSR markers BVWS02309 and BVWS01133. This finding is recommended for use in marker-assisted selection for further development of Fusarium wilt resistant varieties with the newly developed resistant lines serving as source of resistance

A Multi-objectives regression, optimization and risk assessment of profitability indicators of the simulation of mini Liquefied Petroleum Gas (LPG) dispensing unit

In this study, simulation of a mini Liquefied Petroleum Gas (LPG) dispensing unit was conducted using ASPEN HYSYS and the operation of both compressor and pump were validated theoretically. The effect of the economic parameters (Total Annual Sales (TAS), Total Production Cost (TPC), Fixed Capital Investment (FCI) and interest rate (r)) on the behaviour of three profitability indicators (Net Present Value (NPV), Return on investment (ROI) and Internal Rate of Return (IRR)) were modelled and optimized using Box Behnken Design (BBD). The uncertainty of the developed models was determined using Oracle Crystal Ball (ORB). The optimum economic parameters, TAS of ₦48,830,600, FCI of ₦37,422,000, TPC of ₦35, 053,000 and r of 5.4% predicted optimum profitability indicators are ROI of 34.6%, NPV of ₦98,993,580.25 and IRR of 34.15% for 15 years’ investment plan. An interaction of the economic parameters showed that for NPV to be positive, TAS value should be greater than ₦42.5 million and the TPC should be less or equal to ₦36 million. The profitability analysis suggested that this investment will pay back in 2.36 years. Given that the demand of LPG is on the increase and therefore, this LPG plant will be a long term investment with a good return on investment

Marker-assisted introgression of multiple resistance genes confers broad spectrum resistance against bacterial leaf blight and blast diseases in Putra-1 rice variety

Bacterial leaf blight caused by Xanthomonas oryzae pv oryzae (Xoo) and blast caused by Magnaporthe oryzae are major diseases responsible for significant yield loss in rice production across all rice growing regions. Host plant resistance has been advocated as a sustainable means of guarding against the diseases. This experiment was conducted with the aim to introgress multiple resistance genes against bacterial leaf blight and blast diseases through marker-assisted backcross breeding. Two dominant (Xa4 and Xa21) and two recessive (xa5 and xa13) Xoo resistance genes were introgressed into a high yielding Malaysian rice variety Putra-1 with genetic background of three blast resistance (Piz, Pi2 and Pi9) genes. Eight polymorphic tightly linked functional and SSR markers were used for foreground selection of target genes. Seventy nine polymorphic SSR markers were used in background selection. The plants were challenged at initial stage of breeding and challenged again at BC2F2 with the most virulent Malaysian pathotypes of Xoo (P7.7) and Magnaporthe oryzae (P7.2) to test their resistance. Results obtained from foreground marker segregation analysis at BC1F1 and BC2F1 showed that the marker polymorphism both fitted into the Mendel’s single gene segregation ratio of 1:1 for both Xoo and blast resistance. At BC2F2, results indicated that foreground marker polymorphism fitted into the expected Mendelian ratio of 1:2:1 for blast resistance only. Marker-assisted background selection revealed high percentage of recurrent parent genome recovery (95.9%). It was concluded that the inheritance of blast resistance in the introgressed lines was mainly due to single gene action while the inheritance of Xoo resistance was substantially due to single nuclear gene action. The incorporation of four bacterial leaf blight and three blast resistance genes (Xa4 + xa5 + xa13 + Xa21; Pi9 + Pi2 + Piz) in the newly developed lines would provide for broad spectrum and durable resistance against the two major diseases studied

Assessment of Oil Palm Pollinating Weevil (<i>Elaeidobius kamerunicus</i>) Population Density in Biparental <i>dura</i> × <i>pisifera</i> Hybrids on Deep Peat-Soil in Perak State, Malaysia

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

Analysis of recurrent parent genome recovery in marker-assisted backcross breeding program in watermelon

Marker–assisted backcross (MABC) is a breeding technique used to develop improved varieties by transferring a gene or QTL into the genome background of an elite variety after 2-3 generations. It is an advanced way of overcoming challenges facing conventional backcross methods as it speeds up the recurrent parent genome recovery (RPG). In order to develop a Fusarium wilt resistant watermelon variety, MABC was used to incorporate wilt resistant gene from the resistant inbred line CS-19 into the genome of the high yielding but wilt susceptible inbred line BL-14. There was estimation of RPG recovery in earlier generations with the use of polymorphic simple sequence repeat (SSR) markers. A total of 380 SSR markers were tested to identify polymorphism between the parents and 78 of them were found to be polymorphic. Background analysis revealed 74.7 – 94.4 and 86.6 – 96.8 % recovery in BC1F1 and BC2F1 generations, respectively. In the BC2F2 generation, RPG recovery ranged from 95.1 and 96.9 and the average in the selected lines was 96.14 %. This study led to the selection of plants that are similar to the recurrent parent and it showed the usefulness of MABC for the quick recovery of a parental genome in a backcrossing population