Upland rice root characteristics and their relationship to nitrogen uptake

Nitrogen and phosphorus efficiencies are the main constraints to food production in the sub-humid and humid tropic soils. A laboratory and glasshouse study was initiated to examine the differences in the root architecture of Malaysian upland rice landraces and relate them to efficiency of the nitrogen fertilizer uptake. Six upland rice landraces, obtained locally, were soaked in water and allowed to germinate using the cigar role method. The seedlings were fertilized with a complete nutrient solution daily and the roots which were allowed to develop after 14 days were measured using the WINRHIZO. The same landraces were planted in the glasshouse in polybags containing 25 kg soil in four replications. N-15 labelled urea was applied at 170 kg N/ha and N use efficiency was measured at harvest. Significant differences in root length, surface area, root volume, average root diameter, and number of forks, between the 6 landraces were studied. Nitrogen in the plant (derived from fertilizer applied) was found to range from 6.22 – 27.6%. Nevertheless, a poor correlation was obtained between the length of root and the dry matter yield and the total N uptake. Five of the landraces tested showed a good potential in taking up the fertilizer N applied

Mycelial growth interactions and mannan-degrading enzyme activities from fungal mixed cultures grown on palm kernel cake

Palm kernel cake (PKC), a by-product of the palm kernel oil extraction process contains mannan as its main polysaccharide. Mixed culture microbial degradation may enhance mannan-degrading enzymes production. Therefore, the objective of the study was to examine the nature of mycelial interactions and corresponding production of mannan-degrading enzymes of PKC. Fungal interactions was carried out using Sclerotium rolfsii and Aspergillus niger co-cultured with three Trichoderma strains (Trichoderma harzianum, Trichoderma longiobrachiatum and Trichoderma koningii) on potato dextrose agar (PDA) in disposable petri-dishes. Measurements of growth diameters were taken on days 2 and 13. For mannan-degrading enzyme production, single and co-cultures of these fungi were carried out under submerged cultivation for 13 days with PKC as the carbon source. About 57% of observed interactions on PDA were deadlock, 29% replacement and 14% intermingling. In Trichoderma sp./A. niger mixed cultures, there was an overall significant enhancement of enzyme: 2 to 200 fold (β-D-mannanase), 8 to 25 fold (β-mannosidase) and from no change to 15 fold increase (α-galactosidase). There was no obvious relationship between enzyme production and protein yield. However, co-culturing of A. niger with the Trichoderma strains showed an enhancement of mannan-degrading enzyme activities without reducing biomass yield

Model Comparisons for Assessment of NPK Requirement of Upland Rice for Maximum Yield

Upland rice farmers in Malaysia still depend on resultant ash from burning for K and N sources. Efficient use of chemical fertilizers in upland rice needs accurate assessment of required nutrient elements. The present study was performed to determine the N, P, and K requirements of three upland rice varieties grown on idle land (Bukit Tuku soil, AQUIC KANDIUDULT) using four response models. A glasshouse experiment was conducted using 0-200 kg N ha-1 (urea, 46%N), 0-120 kg P2O5 ha-1 (TSP, 45% P2O5), and 0-150 kg K2O ha-1 (MOP, 60% K2O), each at five levels. Three upland rice varieties used in the experiment were Ageh, Kendinga and Strao. The grain yield (14% moisture content) was measured at harvest and fitted using linear (L), linear with plateau (LP), quadratic (Q), and quadratic with plateau (QP) response models. The QP proved itself as the best fitted response model for the determination of fertilizer recommendation rates for maximum yield of upland rice cultivars used. The fertilizer rates were 112 kg N ha-1, 78 kg P2O5 ha-1 and 158 kg K2O ha-1 for Ageh (QP); 138 kg N ha-1 (LP), 87 kg P2O5 ha-1 (QR), 119 kg K2O ha-1 (QP) for Kendinga; and 125 kg N ha-1 (Q), 85 kg P2O5 ha-1 (LP) and 127 kg K2O ha-1 (L) for Strao

Upland rice varieties in Malaysia: Agronomic and soil physico-chemical characteristics

Rice production is a large industry and there are a lot of opportunities which can be obtained from it. Recently, the demand for specialty and high quality rice has increased remarkably, owing to the affluent and health conscious consumers in Malaysia. The research on upland rice has been neglected because of its low yield, though it has many good characteristics, including good fragrance and long grains. Furthermore, it has the advantage of being cultivated on dry land without accumulation of water. Therefore, a large track of idle lands in Malaysia can be developed for this purpose. This study involves a documentation of upland rice in natural conditions. Basic information on the varieties of upland rice which produce high grain yields and quality (fragrance, colour) was collected from selected locations in Peninsular Malaysia, Sabah, and Sarawak. For this purpose, both soil and plant materials (at harvest) were collected. The soil and plant materials were analysed for their macro- and micro-nutrient contents. Standard agronomic characteristics, during growing period and at harvesting time, were also measured. The data were analysed using the SAS statistical software and the mean values were then compared using the Duncan’s New Multiple Range Test (DMRT) at 0.05 level of significance. Seventeen upland rice fields were identified in several locations during the course of this survey. Thirty-five (35) varieties of upland rice seeds were successfully collected. In particular, upland rice and forest soil (as a control) were acidic, contain low nitrogen content and CEC value at 0 – 20 and at 20 – 40 cm depth. Higher Fe content was also observed, with a major limitation for the growth of upland rice. Ageh, Kendinga, and Strao varieties were selected for further evaluation on nutrient requirements using an idle land soil, owing to its growth cycle, productivity, and seed availability

Dry matter and nutrient partitioning of kenaf (Hibiscus cannabinus L.) varieties grown on sandy bris soil

Dry matter and nutrient partitioning of different kenaf varieties grown on sandy Beach Ridges Interspersed with Swales (BRIS) soils were investigated. The experiment was conducted under a shade house condition. Five kenaf varieties, V36, G4, KK60, HC2 and HC95 were grown in pots, replicated four times in a randomized complete block design. Plants were partitioned into roots, stems, and leaves and the dry weights were recorded at harvesting time. The dry matter accumulation differed significantly among varieties. Total biomasses for the different varieties ranged from 56.19g to 63.33g. Stem accounted for the greatest proportion of dry matter (63.98%), followed by root (18.99%). The proportion of the dry matter accumulation in stem was highest (64.28%) in HC2, followed by V36 (64.04%). The average dry matters were 76.83% and 20.56%. in stems and leaves, respectively. The proportion of the macro- and micronutrients in kenaf parts differed significantly among varieties. Nitrogen content had the highest proportion (27.54 to 28.04%) in leaves and lowest (8.06 to 8.24%) in stem, which followed by K, Ca, P and Mg. Most of the kenaf varieties showed variation in nutrient use efficiency (NUE), respect to the measured nutrient elements. The NUE values of < 1.0 g dry matter mg-1nutrient were observed for macronutrients, whereas higher NUE values obtained for micronutrients. Total nutrient accumulation in the plant components differed among the kenaf varieties. Partitioning of dry matter and nutrients in kenaf provides a means to select better varieties and makes it possible to grow kenaf on BRIS soil using better fertilizer program

Analysis of phosphate rock dissolution determining factors using principal component analysis in some acid Indonesian soils

Dissolution of phosphate rock (PR) materials and its subsequent phosphorus (P) availability to plants depend upon soil characteristics, PR characteristics, type of crops, and environmental conditions. Agronomic effectiveness of the PR sources has frequently been investigated in the field or in the greenhouse. This is time consuming and not cost-effective. Therefore, identification of the soil characteristics influencing the dissolution of PR is very important for direct application of P sources. The principal component analysis was used to summarize the characteristics of acid soils in an incubation system into a number of factors that may affect PR dissolution. Three major factors were selected in this study: 1) soil texture, 2) soil acidity, and 3) fertilization. Using the scores of the individual factors as independent variables, a stepwise regression analysis was performed to derive a PR dissolution function. The coefficient of determination (R2) reached 0.91**, and the magnitude of the different factors affect PR dissolution following the order of soil texture (54%) > soil acidity (43%) > fertilizer (3%). Fertilizer was not significant as a PR dissolution factor

Nutrient absorption by oil palm primary roots as affected by empty fruit bunch application

Various parts of the oil palm primary roots were tested to determine the part which absorbs nutrients. An understanding of this aspect of nutrient absorption by the oil palm will explain why the application of empty fruit bunches (EFB) is important. Applying EFB increases the amount of roots, thus increasing the palm’s ability to absorb nutrients and hence, potentially making fertilizer applications more effective. To determine which part of the roots collects and absorbs nutrients, various locations on the primary roots, starting from the root tip, were treated with a solution of KH2PO4 containing 5 μg P ml-1 and 4 μCi of carrier-free 32P. The various locations were identified based on their colour, i.e. creamy white for the root tip, beige for that part of the root just after the creamy white portion, and dark brown for the oldest part of the root. After 24 hr of exposure, the amount of radioactivity emitted from each location was determined. Another experiment was conducted to determine the nutrient distribution pattern in the root after the nutrient was absorbed. In this experiment, the root tip and the part of the root that was dark brown in colour were treated with potassium chloride solution laced with 86Rb for 24 hr. After that time period, about 1 cm of each treated root, starting from the root tip and moving towards the palm base was cut, and their radioactivity determined. Results show that the part of the root that was creamy white (root tip) was significantly more active (P<0.05) in absorbing the nutrient compared to the other parts of the root. The amount of nutrient absorbed at that part of the root increased over time and was significantly higher (p<0.05) at 72 hr compared to absorption at 24 hr. The nutrient distribution pattern in the root from the point of exposure towards the palm base was different when the nutrient was absorbed from the root tip compared to the older part of the root which was dark brown in colour. When the nutrient was absorbed at the root tip, the distribution pattern of the nutrient along the length of the root from the tip to the base of the palm showed a certain pattern. Nutrient concentration was highest at the tip of the root and gradually decreased along the root towards the palm base. However, the nutrient distribution in the treatment of the dark brown part of the root did not follow the same pattern. It is suggested that the nutrient collected within the spaces in the older brown part of the root and flowed towards the root tip before being absorbed. Application of EFB increased the mass of roots. The results imply that for fertilizer application to be more effective, the fertilizers should be applied to those places where most of the roots are formed, i.e. especially under the heaps of EFB

Empty fruit bunch application and oil palm root proliferation.

The benefits derived from the application of empty fruit bunches (EFB) included better yields and improved palm nutrient status. These benefits were the result of better soil conditions after applying EFB. Root proliferation resulting from EFB application was observed to be an important factor that led to the better yields and palm nutrient status. The study was conducted on three-year-old DxP palms. Treatments followed an arrangement for the paired t-test with one side of the palm receiving EFB (treatment) at 100 kg per palm while no EFB was applied to the other side of the same palm (which acted as the control). Root samples were collected at three and six months after EFB application. The root masses from both treatment and control were then analysed as a total of all root orders, and also according to each root order, i.e. primary, secondary and tertiary. Comparison of quaternary roots was made using density/unit tertiary root length. Results showed that there was a proliferation of roots at a depth of 30-45 cm three months after EFB were applied. This proliferation occurred in a soil environment which was significantly improved (p<0.05) in terms of total and exchangeable K and total Ca at 15-45 cm soil depth. Significant (p<0.05) improvements in soil pH, soil moisture and P at 0-15 cm soil depth may also have influenced this proliferation of roots. It is postulated that the increased root mass under improved soil conditions implies an enhanced nutrient uptake process which explains the increased yields and better nutrient status

Evaluation of nutrients released from phosphorus-enriched empty oil palm fruit bunches as growing media using Setaria splendida.

The use of oil palm empty fruit bunch, an agricultural waste from oil palm plantations, as a feeding material for earthworms during composting provides an alternative source of nutrients for plants. Information regarding the ability of earthworms in processing phosphorus-enriched empty oil palm fruit bunch and their effects on plants is still lacking. The objective of this study was to compare the effects of phosphorus-enriched empty oil palm fruit bunches applied as fresh, composted or vermicomposted media in supplying nutrients on a test crop, Setaria splendida L., grass planted on Bungor (Typic Kandiudult) soil. The soil treated with phosphorus-enriched vermicomposted empty oil palm fruit bunch increased the grass dry matter yield significantly higher compared to that treated with composted empty oil palm fruit bunch and control. The root volume of vermicomposted- and composted- empty oil palm fruit bunches treated soil was similar but significantly greater than the control. There was significant interaction between dosage and type of growing media on cumulative N, P, K, Ca, and Mg uptake. However, these factors did not show significant influence on total N, P, Ca and Mg in the soil amended with composted oil palm empty fruit bunch at the end of the experiment. In general, phosphorus-enriched vermicompostedand phosphorus-enriched composted- empty oil palm fruit bunches treated soil resulted in a greater positive effect on growth and nutrient uptake of S. splendida, and also on the total nutrient content in soil except for total K. Total soil K in the control treatment was 242.0 mg/kg and significantly higher compared to soil treated with composted- (173 mg/kg) and vermicomposted- empty oil palm fruit bunches (167 mg/kg). The vermicomposted empty oil palm fruit bunch resulted in better growth performance of the S. splendida in comparison to composted- and fresh- empty oil palm fruit bunches due to the readily available P and other nutrients being readily available to the plants

Genetic analysis of rust resistance genes in global wheat cultivars: an overview

Rust is the most devastating fungal disease in wheat. Three rust diseases, namely, leaf or brown rust caused by Puccinia triticina Eriks, stem or black rust caused by Puccinia graminis f. sp. tritici West, and stripe or yellow rust caused by Puccinia striiformis f. Tritici Eriks, are the most economically significant and common diseases among global wheat cultivars. Growing cultivars resistant to rust is the most sustainable, cost-effective and environmentally friendly approach for controlling rust diseases. To date, more than 187 rust resistance genes (80 leaf rust, 58 stem rust and 49 stripe rust) have been derived from diverse wheat or durum wheat cultivars and the related wild species using different molecular methods. This review provides a detailed discussion of the different aspects of rust resistance genes, their primitive sources, their distribution in global wheat cultivars and the importance of durable resistant varieties for controlling rust diseases. This information will serve as a foundation for plant breeders and geneticists to develop durable rust-resistant wheat varieties through marker-assisted breeding or gene pyramiding