The physico-chemical and mineralogical characterization of Mg-rich synthetic gypsum produced in a rare earth refining plant

The physical, chemical and mineralogical characterization of the constituents of magnesium-rich synthetic gypsum produced in a rare earth-refining plant located in Gebeng, Pahang, Malaysia was conducted through elemental chemical analysis, scanning electron microscopy with Energy Dispersive X-ray (EDX)-analyzer, thermal analysis, X-ray fluorescence and X-ray diffraction. The crystalline nature of the by-product was studied using FTIR spectroscopy. Elemental analysis confirmed the presence of Ca and Mg, which are essential macronutrients required by plants and this Ca alongside the high pH (9.17) of MRSG may confer on the material a high acid neutralization capacity. From the result, it was observed that the studied by-product is a heterogeneous crystalline material comprising of gypsum (CaSO4.2H2O) and other major components such as calcium (magnesium) compounds (hydroxide, oxide, silicates, and carbonate) and sulfur. These aggregates may contribute to give an acid neutralization capacity to MRSG. The XRD study of MRSG indicated a high content of gypsum (45.4%), shown by the d-spacing of 7.609 Å (2-theta 11.63) in the diffractogram. The infrared absorption spectra of MRSG indicate close similarities to mined gypsum. The results of the characterization indicated that MRSG has valuable properties that can promote its use in amending soil fertility constraints on nutrient-deficient tropical acid soils

Genetic diversity and utilization of cultivated eggplant germplasm in varietal improvement

Eggplant is the fifth economically most important vegetable in the Solanaceae family after tomato, potato, chili, and tobacco. Apart from the well-cultivated brinjal or aubergine eggplant (Solanum melongena L.), two other underutilized eggplant species, the African eggplant (S. macrocarpon L.) and the scarlet eggplant (S. aethiopicum L.), were also cultivated with local importance where the leaves and fruits are used for food and medicinal purposes. The major objectives of the eggplant breeding program are to improve fruit quality, increase yield performance through heterosis breeding, and introduce pest and disease resistances from wild relatives. Europe and Asia hold a wide collection of germplasm resources with significant potential for genetic improvement. While cultivated eggplant is susceptible to several fungi and bacteria, many wild relatives offer potential resistance to these pathogens. In this paper, we review the genetic resources and diversity of cultivated eggplant and its wild relatives. As a point of departure, we examine the economic importance, domestication, taxonomy characterization, and relationships of the crop and its wild relatives. The importance of evaluating and safeguarding wild relatives is highlighted, as crop wild relatives are highly underrepresented. A key section in this study is an overview dedicated to genetic resources, resistance to biotic and abiotic stresses, pre-breeding, and breeding for sustainable eggplant production

Genetic diversity in eggplant (Solanum melongena L.) germplasm from three secondary geographical origins of diversity using SSR markers

Indo-Burmese region was the primary center of eggplant diversity from where the crop extended to several secondary origins of diversity. In this study, the genetic diversity among fifty-six eggplant accessions collected from three countries was assessed using sixteen polymorphic SSR markers to determine suitable parents for heterotic hybridization. The estimation of genetic diversity among the population of three countries (Bangladesh, Malaysia, and Thailand) varied from 0.57 to 0.74, with Shannon’s index value of 0.65. The mean value of expected heterozygosity and Nei’s index was 0.49, with an average PIC value of 0.83. A dendrogram was constructed based on UPGMA (unweighted pair group method with arithmetic mean), and the dendrogram categorized all accessions into six groups. The AMOVA (analysis of molecular variance) revealed a 77% total variation within the population from three different countries and 23% total variation among the populations. The result revealed a high genetic differentiation among the eggplant germplasms while the accessions that are farther from each other show a high level of diversity; thus, they can be recommended as parental in breeding programs. Hence, accessions, EB12, ET11, ET13, ET15, ET16, and ET17 could be crossed with accessions EM3, EB34, and EB3 for improvement in the future breeding program

LEA gene expression asssessment in advanced mutant rice genotypes under drought stress

Late embryogenesis abundant (LEA) proteins are primarily found in plants stem, roots, and other organs and play significant roles in tolerance to several abiotic stresses. Plants synthesize a discrete set of LEA proteins in response to drought stress. In this study, the expression patterns of LEA genes were investigated in two advanced mutant rice genotypes subjected to the drought stress condition and different physiological traits including photosynthetic rate, leaf chlorophyll content, and photosystem II (PSII) photochemical efficiency (Fv/Fm) which were analyzed to confirm their drought tolerance. Five LEA genes (OsLEA1, OsLEA2, OsLEA3, OsLEA4, and OsLEA5) were used in the evaluation of rice genotypes and were significantly upregulated by more than 4-fold for MR219-4 and MR219-9. The upregulated genes by these two varieties showed high similarity with the droughttolerant check variety, Aeron1. This indicates that these advanced mutant genotypes have better tolerance to drought stress. The changes in the expression level of LEA genes among the selected rice genotypes under drought stress were further confirmed. Hence, LEA genes could be served as a potential tool for drought tolerance determination in rice. MR219-4 and MR219-9 were found to be promising in breeding for drought tolerance as they offer better physiological adaptation to drought stress

Characteristics of magnesium rich synthetic gypsum and its effect as a secondary nutrient source for rubber seedlings on acid soils

Ultisols and Oxisols, the common soil in Malaysia, do not usually contain optimal levels of cations such as K, Ca and Mg, required in large amounts for crop growth and productivity. Thus, the management of input plays an important role in crop production in these widely occurring soils of Peninsular Malaysia. Rubber requires large amounts of nutrients to sustain its growth and production so that faster growth and high latex yield can be achieved and maintained. The use of fertilizer to supply nutrients for rubber is essential in rubber cultivation; however, fertilizer costs account for a larger percentage of production costs. As such, it is imperative to seek for a local alternative source that is cost-effective. Recent studies on MRSG, a by-product obtained from industrial refining of rare earth show that the material contains nutrient elements that may be beneficial for rubber growth in addition to its high pH that ameliorate the impact of soil acidity limitation on crop growth. Therefore, this research was conducted to study the physicochemical characteristics of MRSG, its effect on acid soils, rubber growth, and whether MRSG can be a secondary nutrient source for rubber plants at the growing phase. The characterization results indicated that MRSG has valuable properties that can promote its use in amending soil fertility constraints on nutrient-deficient tropical acid soils. Incubation and leaching column studies were conducted to assess the effect of MRSG on the chemical properties of Ultisol and Oxisol in Malaysia and model the nutrient release pattern from the material over a 6-month period. The incubation experiment was as a factorial experiment consisting of 2 soil types, 3 treatments and five rates including control (0, 1, 2, 4 and 8) and laid out as a completely randomized design (CRD). For the leaching experiment, the treatment consists of 1 t ha-1 of MRSG, GML and kieserite with three replications arranged in a complete randomized design (CRD). The study comprised two soil orders viz Ultisol and Oxisol belonging to the Bungor and Segamat series based on Malaysian classification for local soils. The amount of nutrients released into soil solution and present on the soil exchange site due to the application of MRSG at various rates and months were fitted into different functions using python programming script. The pattern of nutrient release from MRSG was similar in the two studied soils and amounts of nutrient released increased with the duration of the experiment. Nutrients release kinetics for all samples are adequately described by the parabolic diffusion, power function and Elovich equations. The intercept constants of the equations are strongly positively related to the ratio of nutrients contained in MRSG. The models showed good performance (R2 value in range 0.9 to 0.99) in most samples tested except for the kieserite treatment group. The model indicates that MRSG has a disintegration behavior similar to GML and can be used to achieve a similar result in acid soil amelioration and soil nutrient enhancement. The leaching study showed that MRSG is available in the soil system and can move beyond the zone of incorporation into the sub-soil to further ameliorate subsoil acidity. The Ca and Mg ions contained in MRSG are not easily leached out of the soil profile, thus MRSG can be a potential substitute for lime (GML) on acid soils. For nursery trial to understand the effect of MRSG application on the growth of immature rubber, three-month-old rubber seedlings of the same size and/or height were obtained from RISDA for planting on Ultisol and Oxisol. The experimental units consisted of four rubber seedlings, with a total of 200 seedlings planted in the polybags. Treatments for this study was based on using GML, kieserite and MRSG as fertilizer source to supply the recommended Mg requirement for rubber seedlings in the nursery based on RISDA formulation. Determination of growth parameters of the rubber seedlings was carried out at 3 monthly intervals. The result of the experiment showed that incorporation of MRSG increased the soil pH and decreased the aluminum content. MRSG application also increased the level of available phosphorus and secondary nutrients such as calcium. The growth of rubber seedlings in the glasshouse for the parameters of height, stem diameter, root length and root surface area were significantly enhanced in the two studied soils (Ultisol and Oxisol) by the addition of MRSG which gave a result comparable to other sources of Mg fertilizer. It was observed that plant growth performance was better on the Ultisol compared to the Oxisol. This study showed that the logistic growth curve model in the form of y = A/ (1+be-ct), where y and t were the plant growth parameters and months after transplanting, respectively, while A, b and c were regression constants were biologically fitted in describing the growth in terms of each of the parameters (plant height, stem girth and total plant biomass) versus months after transplanting. At each treatment, the model had an F value with a high approximate probability level at a = 0.0001. In terms of the vegetative growth of the rubber seedlings, MRSG treatments gave comparable results to that of GML and kieserite, thus, indicating the possibility of using MRSG as a replacement of kieserite and GML as Mg source (Mg-fertilizer) to sustain rubber seedling growth

Effect of magnesium rich synthetic gypsum application on ultisol properties and growth of oil palm seedlings

Oil palm cultivation in Malaysia is mainly on the acidic Ultisols and Oxisols, which are highly weathered with low fertility. Despite the problem of low soil productivity, the good physical makeup of the soil makes them suitable for sustainable oil palm cultivation. This study consisted of two parts. The first study was a field work conducted in an oil palm plantation at Bera, Pahang, in an attempt to classify the dominant soil types in the area and to determine their suitability for oil palm cultivation. The second study was a glasshouse trial at Universiti Putra Malaysia using oil palm seedlings planted in polybags, containing Ultisols collected the oil palm plantation. For the field study, a soil pit was dug for profile description on soil morphological characteristics, and samples were collected based on genetic horizons for analyses. Only one soil series was identified in the area under study. The main objective of this study was to evaluate the performance of magnesium rich synthetic gypsum (MRSG) obtained from a rare earth refining company in Malaysia (Gebeng, Pahang) as a potential magnesium source in fertilizer programme for sustainable oil palm cultivation in Malaysia. The soil under study was formed under tropical environment with udic moisture regime on fine-grained sedimentary rocks, mixed with tuffs of Permian age. The soil in the area was reddish in colour, clayey, deep and highly weathered. The clay fraction of the soil was dominated by kaolinite, gibbsite, goethite, and hematite; thus, the plant nutrient status of the soil is low. The exchangeable aluminium in the soil was low, although the soil has an acidic reaction in water. Taxonomically, the soil was classified as Clayey Kaolinitic, isohyperthermic, Typic Paleudult due to its colour and the presence of diagnostic argillic horizon in the B-horizon (Bt). From the results of this study, it was deduced that the inherent soil properties in the field situation had no significant limitation for oil palm cultivation; hence, with proper agronomic practices, the area can be utilized for sustainable oil palm cultivation.In meeting up with the world demand for oil palm products, the industry needs to sustain high productivity. This requires regular application of high amount of fertilizers, one of which is Mg-fertilizer. A glasshouse study for 9 months, using oil palm seedlings, was conducted to examine the effectiveness of MRSG as a source of Mg for oil palm cultivation. In this study, plant performance, nutrient uptake, soil chemical characteristics, and population of soil microbes in comparison with other Mg fertilizer sources, such as ground magnesium limestone (GML) and kieserite (MgSO4.7H2O) were determined. The experimental design was Randomized Completely Block, with 7 treatments and 6 replications, the treatments were: T1- NPK without source of Magnesium; T2 - NPK + Kieserite at standard rate; T3 - NPK + GML at standard rate; T4 - NPK + MRSG at the recommended rate; T5 - NPK + MRSG at one-half the recommended rate; T6 – NPK + MRSG at double the recommended rate; T7 - NPK+ MRSG to equivalent amount of Ca in GML. Soil parameters at 0, 3, 6 and 9 months measured were pH, EC, exchangeable cations, carbon, nitrogen, sulphur and selected micronutrients, while the plant parameters were growth traits, fresh and dry biomass of the seedlings root and above ground portion, macronutrients (Ca, Mg, P, and K) and micronutrient (Zn and Mn). Results showed that there were significant responses among soil to treatments; Treatment (T7) containing 36 gram of Mg i.e MRSG applied at double the recommended rate of magnesium required by oil palm seedlings showed the highest increase of soil pH (6.82), exchangeable calcium (1.52 cmolc/ kg), magnesium (0.59 cmolc/ kg) and total sulphur (0.07 %) in the soil, while the above-measured parameters were lowest in control. The exchangeable aluminium of the soil was low as soil pH under field condition was above 5. GML treatment (T3) was able to increase soil pH that helped enhance oil palm growth. It was found that kieserite (MgSO4.7H2O) treatment had a significant effect on soil fertility, especially in terms of increase in exchangeable magnesium and total sulphur. It was found that MRSG treatments (T4, T5, T6 and T7) had positive effect on soil fertility, shown by the increase in exchangeable Mg, Ca and soil pH. MRSG application did not have negative effect on microbial activities in the soil. Due to the improved soil fertility, the growth of the oil palm seedlings in terms of height, bole diameter, chlorophyll index and root performance was as good as those planted on soil treated with GML or kieserite. As such, Magnesium rich synthetic gypsum can replace kieserite as Mg source for immature oil palm cultivation

Impact of Oil Palm Empty Fruit Bunch Biochar Enriched with Chicken Manure Extract on Phosphorus Retention in Sandy Soil

A 45-day incubation and leaching experiments was conducted to determine the effect of different rates (0, 1, 2, 3, and 5 t ha−1) of enriched empty fruit bunches biochar (EEFB) and inorganic fertilizer (91 kg ha−1 triple superphosphate—TSP) on the availability and leaching losses of phosphorus from sandy soil (tin tailing soil). The treatments rates for the study were designated as T1—without fertilizer (control), T2—inorganic fertilizer treatment using TSP and T3, T4, T5, and T6, which refers to EEFB rate of 1, 2, 3, and 5 t ha−1, respectively. The enriched biochar was prepared by shaking biochar with chicken manure extract for 24 h. The addition of EEFB to the soils was found to increase pH of the soil compared to control and inorganic fertilizer treatment. After 45 days of incubation, the percentage increase in available P recorded in EEFB treatments were 1.6, 2.9, 2.8, and 4.1%, whereas for control treatment and inorganic fertilizer treatment, the available phosphorus was found to reduce by 10% and 83%, respectively. Loss of phosphorus via leaching in the soil was higher in EEFB treatments compared to control. However, the highest phosphorus leaching among all treatments in this study was recorded in inorganic fertilizer treatments. From the study, it was observed that biochar can be used to recapture phosphorus from chicken manure extract for transport to the soil, thereby reducing problems associated with chicken manure application

Utilization of magnesium-rich synthetic gypsum as magnesium fertilizer for oil palm grown on acidic soil.

A study was conducted to determine the impact of applying different sources of Mg, namely kieserite, ground magnesium limestone (GML) and Mg-rich synthetic gypsum (MRSG) on an acid tropical soil, oil palm growth and production. Besides high amount of Mg and Ca, MRSG contains S. Exchangeable Ca in the untreated soil of the plantation was 0.64 cmolc kg-1, but its critical level to sustain oil palm growth was 0.9 cmolc kg-1. MRSG was applied in the plantation as Mg-fertilizer; however, since Ca is also a limiting nutrient, oil palm growth was correlated (r = 0.69) with Ca supplied by the MRSG. Mg needed to sustain oil palm production is normally supplied by kieserite. Its requirement can be met at a lower cost compared to that of the kieserite by using MRSG. Due to MRSG treatment, exchangeable Ca in the soil increased steadily to satisfy the requirement of oil palm for fruit bunches production. From the glasshouse and field study, it was observed that MRSG applied at 1.5 times the recommended rate gave results comparable to that of the kieserite. MRSG treatment resulted in the increase of soil pH to >5 that precipitated Al3+ as inert Al-hydroxides, which eventually enhanced oil palm seedlings growth. Thus, MRSG can also replace GML to increase soil pH and satisfy the Ca and Mg requirement of oil palm. It can be concluded that MRSG has the potential to be used as a source of Mg as well as Ca for oil palm grown on acidic soil

Effect of salt-tolerant bacterial inoculations on rice seedlings differing in salt-tolerance under saline soil conditions

Salt-tolerant plant growth-promoting rhizobacteria (PGPR) could be an alternative to alleviate salinity problems in rice plants grown in the coastal areas. This study was conducted to isolate and characterize salt-tolerant PGPR and observe their effects on the physiological and biochemical properties of rice plants grown under non-saline and saline glasshouse conditions. Three strains were selected based on their salt-tolerance and plant growth-promoting properties under in vitro saline conditions. These strains were identified as Bacillus tequilensis (UPMRB9), Bacillus aryabhattai (UPMRE6), and Providencia stuartii (UPMRG1) using a 16S rRNA technique. The selected strains were inoculated to three different rice varieties, namely BRRI dhan67 (salt-tolerant), Putra-1 (moderate salt-tolerant), and MR297 (salt-susceptible) under glasshouse conditions. Results showed that the MR297 rice variety inoculated with UPMRB9 produced the highest total chlorophyll content, with an increment of 28%, and lowest electrolyte leakage of 92%. The Putra-1 rice variety also showed a 156% total dry matter increase with the inoculation of this bacterial strain. The highest increase of relative water content and reduction of Na/K ratio were found upon inoculation of UPMRE6 and UPMRB9, respectively. The biggest significant effects of these bacterial inoculations were on relative water content, electrolyte leakage, and the Na/K ratio of the BRRI dhan67 rice variety under saline conditions, suggesting a synergistic effect on the mechanisms of plant salt-tolerance. This study has shown that the application of locally-isolated salt-tolerant PGPR strains could be an effective long-term and sustainable solution for rice cultivation in the coastal areas, which are affected by global climate change

Submergence tolerance in rice: review of mechanism, breeding and, future prospects

Flooding or submergence is one of the major environmental stressors affecting many man-made and natural ecosystems worldwide. The increase in the frequency and duration of heavy rainfall due to climate change has negatively affected plant growth and development, which eventually causes the death of plants if it persists for days. Most crops, especially rice, being a semi-aquatic plant, are greatly affected by flooding, leading to yield losses each year. Genetic variability in the plant response to flooding includes the quiescence scheme, which allows underwater endurance of a prolonged period, escape strategy through stem elongation, and alterations in plant architecture and metabolism. Investigating the mechanism for flooding survival in wild species and modern rice has yielded significant insight into developmental, physiological, and molecular strategies for submergence and waterlogging survival. Significant progress in the breeding of submergence tolerant rice varieties has been made during the last decade following the successful identification and mapping of a quantitative trait locus for submergence tolerance, designated as SUBMERGENCE 1 (SUB1) from the FR13A landrace. Using marker-assisted backcrossing, the SUB1 QTL (quantitative trait locus) has been incorporated into many elite varieties within a short time and with high precision as compared with conventional breeding methods. Despite the advancement in submergence tolerance, for future studies, there is a need for practical approaches exploring genome-wide association studies (GWA) and QTL in combination with specific tolerance traits, such as drought, salinity, disease and insect resistance