TOLERANCE OF IRRIGATED LOWLAND RICE VARIETIES TO IRON TOXICITY UNDER NUTRIENT SOLUTION AS MEASURED BY A DIGITAL IMAGE PROCESSING

Freshwater consumption is the biggest challenge in irrigated rice cultivation (Oryza sativa L.). Nonirrigated farmland rice cultivation is a strategy to mitigate the water resource shortage associated with traditional irrigated rice farming. Both nonirrigated farmland and irrigated rice face challenges from insect pest attacks, yet the comparative responses of rice grown under these two cultivation methods to insect herbivory have not been extensively studied. In this study, we observed that the population density of the oriental armyworm (Mythimna separata) was higher in nonirrigated farmland rice compared to irrigated rice. To investigate the molecular and metabolic responses of rice to insect feeding, we conducted integrated transcriptomic and metabolomic analyses following 48 h of continuous herbivory by oriental armyworm larvae. Our results showed that insect feeding induced a more pronounced change in the number of differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) in irrigated rice than in nonirrigated farmland rice. These DEGs and DAMs were significantly enriched in plant hormone signal transduction pathways. In-depth analysis revealed that the abscisic acid and salicylic acid signaling pathways and the auxin biosynthesis pathway were more responsive to oriental armyworm feeding in irrigated rice compared to nonirrigated farmland rice. Additionally, jasmonic acid biosynthesis and signaling pathways were activated in both irrigated and nonirrigated farmland rice under herbivory stress. In summary, this study provides evidence that nonirrigated farmland rice exhibits a reduced response to insect feeding compared to irrigated rice. These findings contribute to nonirrigated farmland rice resistance or tolerance research and potential applications in pest management.

In the changing climatic condition, temperature is the most vulnerable parameter and is projecting a trend of increase in the future. Crop growth and development process depend largely on air temperature. This study aims to determine the role of increasing air temperature in yield, crop water requirement (CWR), and other agronomic parameters of irrigated rice. Ceres-rice model associated in the Decision Support System for Agrotechnology Transfer (DSSAT) was used in 15 different locations of Bangladesh. Grain yield, growth duration, and crop water requirement of widely cultivated irrigated rice (Boro rice) variety BRRI dhan28 were analysed in normal temperature and elevated air temperature by 1°C, 2°C, 3°C, and 4°C. The result revealed detrimental effect of elevated temperature on growth duration and grain yield. The estimated highest growth duration reduction of 30 days was found in Moulvibazar for 4°C temperature rise. The grain yield reduction was projected by 0–17%, 16–35%, 31–49%, and 39–61% from the normal condition if the seasonal mean temperature increased by 1°C, 2°C, 3°C, and 4°C, respectively. The country average crop water requirement was found to be 405 mm of which the highest 445 mm and the lowest 358 mm were recorded in Moulvibazar and Chandpur, respectively. The study revealed that the country average rice CWR reduced by 5%, 8%, 12%, and 17% over the normal condition for 1°C, 2°C, 3°C, and 4°C rising temperature, respectively. For 1°C temperature rise, BRRI dhan28 life span shortened by 6.4 days, grain yield reduced by 695 kg, and estimated CWR decreased by 14 mm. The projected declining CWR indicated that irrigated rice will require less irrigation water, but it will cause considerable yield loss under elevated temperature. Though elevated temperature will save huge irrigation water used in country-wide Boro rice cultivation, the crop developers need to introduce new heat-tolerant cultivar to minimize yield loss.

Purpose: Canopy light interception and extinction play a crucial role in determining crop yield. Developing new rice varieties with improved canopy architecture along with modified intrinsic photosynthetic mechanisms will ensure the global food security. However, a comprehensive understanding of local rice varieties addressing on such avenues have not been reported. Hence, our pioneering experiments were carried out to elucidate such underlying properties among locally developed two elite rice varieties viz; At-362 and Bg 94-1 grown in the Ampara district of Sri Lanka. Research Method: The field experiment was carried out at the Agro Tech Park, Malwatta (7°20'N and 81°44'E altitude 16.0 m above sea level) between October 2019 to January 2020 implemented with Randomized Complete Block Design with four replicates. The Photosynthetically Active Radiation (PAR) distribution on the above and below canopy level was measured during the pre and post-anthesis stages. Then leaf stomatal conductance, chlorophyll fluorescence parameters and the chlorophyll content were also measured. At harvest, the final biomass produced were compared. Findings: The result revealed that variety At-362 had a higher Leaf Area Index (LAI) of 2.64 at pre anthesis and tend to decline at the latter part of their growth cycle. The striking feature was the extinction coefficient (k) seems to be much lower (0.47) in the At-362 variety than the Bg 94-1 (0.60) depicting that the former has produced vertical leaves (erect-leaf type) while the latter tends to produce horizontal leaf plans in the canopy. Hence, light attenuation was high and eventually, the bottom canopy layer received much lower PAR. Furthermore, LAI had a strong negative correlation with understory PAR indicating that the canopy architecture with an improved light interception will lead to permit more light penetration and utilization through the improved quantum yield efficiencies than the horizontal canopies. Hence significantly (p<0.05) improved above-ground biomass and panicle weight were observed in At-362. Originality/value: This experiment depicts that rice yield could be further improved through introgression of canopy architectural features along with improved photosynthetic traits.

Arbuscular mycorrhizal fungi (AMF) enhance the uptake of water and nutrients by host plants. In this study, we examined the response of six rice varieties from two ecotypes (three irrigated and three rainfed upland varieties) to AMF inoculation at five fertilizer levels, under continuous flooding (CF) and alternate wetting and drying (AWD) irrigation over two consecutive years in field conditions. Both irrigated and upland rice varieties experienced significant yield losses with AWD irrigation and reduced NPK fertilizer levels, with irrigated rice being more severely affected. Under AWD irrigation, AMF inoculation mitigated relative yield losses, especially when half of the recommended fertilizer dose was applied. In CF conditions, AMF inoculation often fully compensated for yield losses caused by reduced NPK levels. Furthermore, irrigation regime, fertilizer levels, and ecotype were significant sources of variation in the effects of AMF inoculation on several yield-related traits, such as total biomass, tiller number, panicle number, fertility, and maturity dates. Our findings suggest that AMF inoculation could be integrated with AWD irrigation and/or low NPK inputs to contribute to fertilizer and water savings in both irrigated and upland rice production systems.

Management of phosphorus, potassium, and sulfur in intensive, irrigated lowland rice

Introduction: The development of tolerant rice genotypes is the main tool to minimize the problem caused by the excess of iron in the soil.
 Aims: The study aims to evaluate the response of genotypes of the Embrapa breeding program of irrigated rice against iron stress, as well as to envision the relationship of the effect of this disorder on leaf mass production in different phenological phases of the plant.
 Study Design: The trial was established in a randomized block design with additional controls, with the plots consisting of four rows 3 m long with 0.20 m spacing between rows.
 Place and Duration of Study: The experiment was conducted in the experimental field of Embrapa Temperate Climate Lowlands Station, in a period of nine years, consisting of the harvest of 2006/2007 until 2014/2015.
 Methodology: It was evaluated 255 lines along with 4 additional control cultivars with known tolerance levels. The symptoms were evaluated at 40, 70 and 100 days after plant emergence through a visual assessment in the field, based on the standard evaluation system for rice. In addition to the determination of the average toxicity levels of genotypes, the mass was collected, constituted by the dry matter of shoot, for the detection of interrelationships through their correlations.
 Results: It was found that 58.82% of the developed irrigated rice lines show good tolerance to toxicity by excess iron. The association of the content of dry matter of shoots and the levels of indirect toxicity of iron showed a significant negative correlation (-0.6848), being that the highest magnitude of negative correlation was at 70 DAE (-0.6161).
 Conclusion: There is variability for tolerance to indirect iron toxicity between the irrigated rice genotypes assessed. The breeding program of irrigated rice of Embrapa has been effective in developing genotypes with tolerance by excess iron in the soil over nine years. There is a negative association between the content of dry matter of shoots and the levels of indirect iron toxicity.

Genes of tolerance for herbicide has become one of the options more used in world level for the weed control. This study had as objective to evaluated crosses between tolerant irrigated rice plants and sensitive to herbicides of the imidazolinone chemical group, through the evaluation of F2 populations. Five genotypes of irrigated rice were crossed. Three of these parents are sensitive to the herbicide: BRS Querencia, BRS Fronteira and BRS Pampa and two genotypes, BRS Sinuelo CL and Puita INTA CL, tolerant to the herbicide. F1 seeds were obtained in greenhouse, and generation advance was performed in Embrapa Rice and Beans, resulting in the F2 population. F2 plants in the stage V4 received herbicide applications of (Only®) at a dose of 75 and 25 g a.i. L−1, and Dash® in dose of 0.5% v/v. A second application was performed after one week. The degree of phytotoxicity was scored as dead leaves and phytotoxicity intensity, percent survival of leaves and the relative growth. The results showed that the F2 hybrids, resulting of the crosses between the cultivars carriers of the gene of herbicide tolerance of the imidazolinone (Only®) class and conventional irrigated rice cultivars, are viable, thus enabling the establishment of herbicide-tolerant irrigated rice populations, with greater capacity to fight the red rice and with characteristics of agronomic interest. F2 progenies descending from crosses with the cultivar Puita INTA CL presented more tolerance when compared with progenies descending from crosses with the cultivar BRS Sinuelo CL.

The major quantitative trait locus (QTL) Phosphorus uptake1 (Pup1) confers tolerance of phosphorus deficiency in soil and is currently one of the most promising QTLs for the development of tolerant rice (Oryza sativa) varieties. To facilitate targeted introgression of Pup1 into intolerant varieties, the gene models predicted in the Pup1 region in the donor variety Kasalath were used to develop gene-based molecular markers that are evenly distributed over the fine-mapped 278-kb QTL region. To validate the gene models and optimize the markers, gene expression analyses and partial allelic sequencing were conducted. The markers were tested in more than 80 diverse rice accessions revealing three main groups with different Pup1 allele constitution. Accessions with tolerant (group I) and intolerant (group III) Pup1 alleles were distinguished from genotypes with Kasalath alleles at some of the analyzed loci (partial Pup1; group II). A germplasm survey additionally confirmed earlier data showing that Pup1 is largely absent from irrigated rice varieties but conserved in varieties and breeding lines adapted to drought-prone environments. A core set of Pup1 markers has been defined, and sequence polymorphisms suitable for single-nucleotide polymorphism marker development for high-throughput genotyping were identified. Following a marker-assisted backcrossing approach, Pup1 was introgressed into two irrigated rice varieties and three Indonesian upland varieties. First phenotypic evaluations of the introgression lines suggest that Pup1 is effective in different genetic backgrounds and environments and that it has the potential to significantly enhance grain yield under field conditions.

Farmers, as parties who have an important role in meeting people's food needs in agriculture, should have high selling prices and their welfare should be taken into account by the government. Agricultural development is a means of effort to improve the standard of living of farmers, increase income, expand employment and business opportunities, and expand markets both domestically and abroad. This can be achieved through advanced, efficient and resilient agriculture so that it can increase yields, improve quality and support regional development. This study aims to analyze income, efficiency and costs of irrigated lowland rice farming in Wonosari district, Klaten. The method used in this research is to determine the sample by means of purposive sampling. Data analysis uses farming analysis such as analysis of income, efficiency and costs. The results of this research are the average income earned on irrigated rice fields in Wonosari District Rp. 10,542,703.72/Ha. Farming costs obtained by irrigation rice farmers amounted to IDR 11,009,059.63/Ha. Revenue for irrigated lowland rice farming is IDR 21,551,763.35/Ha and the efficiency of irrigated lowland rice farming in Wonosari District is IDR 2.0.

This present study which is base on the effect of pest insects on the production of rice was done in the Far North Cameroon in the irrigated rice ecosystem of Maga. On one part, it consisted of the determination of the biological diversity of pest insects of rice in the rice ecosystem of Maga, to evaluate the damages and the dynamism of pest insects on the phenologic stage of rice and on the other part and to evaluate the effect of insecticide lynx on the pest insects and the production of rice. A split plot disposition of two rice varieties (irrigated rice variety IR 46 and the rainy season rice variety NERICA 3) and two treatments (control and chemical treatment) were adopted. The insects were captured with the help of a sweep net on every portions on the phenologic stages of rice, from the 15th day after planting to harvesting. This method of collecting insects consists of sweeping insects, on the portions or 50 sweeps per portion. These collections of pest insects on the two rice varieties have permited us to see the dynamism of pest insects on the different phenological stages of rice, and a knowledge on their abundance. The results obtained on the biological diversity have shown that 2465 pest insects of rice were collected on the IR 46 variety and 3264 on the NERICA 3 variety. Concerning the dynamism of the pest insects, we have observed a variation of the number of pest insects following the different phenological stages of rice. Concerning the damages due to the pest insects, lose due to these pest insects was evaluated at 49.98% total, 26.30% lose at the talling stage and 23.68% at the harvest on the two varieties. The chemical insecticide lynx have reduced the pest at a rate of 12.585% in the nursery, 20.4725% at the talling stage, 9.305% at the ear and 8.7325% at maturity. The output was obtained at 2.13 t/ha for the IR 46 variety and 1.91 t/ha for the NERICA 3 variety. This result permits us to say that many pest insects occupies the irrigated rice ecosystem of Maga, they are dynamic and leads to the damages on the rice production. The insecticide lynx used permit the reduction of the pest insects and hence increasers production.

Many studies have revealed that water mite communities can be affected by the physical and chemical parameters of the water. The similarity between the water ‘mite assemblages in local water bodies and in irrigated rice areas can be a way to measure the water conditions, enabling an assessment of the anthropic impact in the environment. The aim of this study was to evaluate the distribution of water mites in lakes and irrigated rice fields in south Brazil. To accomplish that we characterized the distinctive environments using physical and chemical variables such as pH, turbidity (NTU), water temperature (°C) and dissolved oxygen (mg/L), in order to verify the influence of these abiotic factors on the species composition of water mite communities; and to compare water mite abundance, richness and composition among different habitats. We assessed three native lakes and four sites with irrigated rice cultivation. Our results showed, for the first time in Brazil, strong correlations between the water mite fauna and turbidity. In addition, native lakes were richer and had greater mite abundance when compared with the irrigated rice areas.

De Vries compiled a historical review of agricultural development in the Regency of Pasuruan (East Java) from the beginning of the nineteenth century until 1929. Special attention was given to the sugar industry, coffee, pepper, indigo culture, animal husbandry, irrigation, trade, fisheries and handicrafts. Much information was given on demographic situation, landownership, land tenure, credit provisions, human diet, use of irrigated fields (sawahs), rice varieties, rice productivity, the coconut, kapok and mangga illustrated by tables and charts. Detailed aspects of the agriculture in a small district (Poh-djentreck) near the town of Pasuruan were presented. The book ends with some suggestions and deliberations on ways of improving the welfare of the county.

Growth and yield of modern deepwater rice: Comparisons with modern irrigated rice

SummaryTillering plays an important role in determining rice grain yield. Several models have been developed to predict tiller production in irrigated rice. In this paper we tested three models using data drawn from a wide range of plant densities and N inputs in two field experiments conducted at the International Rice Research Institute, Philippines during the 1997 and 1998 dry seasons. Two rice cultivars (IR64 and IR72) were used in the experiments. Plant samples were taken at intervals to determine number of tillers, leaf area index (LAI), biomass, relative growth rate (RGR) and leaf N concentration. The models were parameterized using an iteration procedure of the simplex method. Previous models (TIL and SINK) using the original values of parameters for IR64 failed to predict the number of tillers of IR64 in 1997. However, when re-parameterized, both models described the 1997 data well for both cultivars. The two models also predicted fairly well the number of tillers of different transplanting spacing and N input treatments of IR72 in 1998 using IR72 parameters derived from the 1997 experiment. A simple RGR model was comparable with the TIL and SINK models in descriptive and predictive ability. It appears that all three models could be used for predicting tiller production of irrigated rice.

Salinity is a major yield-reducing factor in coastal and arid, irrigated rice production systems. Salt tolerance is a major breeding objective. Three rice cultivars with different levels of salt tolerance were studied in the field for growth, sodium uptake, leaf chlorophyll content, specific leaf area (SLA), sodium concentration and leaf CO2 exchange rates (CER) at photosynthetic active radiation (PAR)-saturation. Plants were grown in Ndiaye, Senegal, at a research station of the West Africa Rice Development Association (WARDA), during the hot dry season (HDS) and the wet season (WS) 1994 under irrigation with fresh or saline water (flood water electrical conductivity = 3.5 mS cm-1). Relative leaf chlorophyll content (SPAD method) and root, stem, leaf blade and panicle dry weight were measured at weekly intervals throughout both seasons. Specific leaf area was measured on eight dates, and CER and leaf sodium content were measured at mid-season on the first (topmost) and second leaf. Salinity reduced yields to nearly zero and dry-matter accumulation by 90% for the susceptible cultivar in the HDS, but increased leaf chlorophyll content and CER at PAR- saturation. The increase in CER, which was also observed in the other cultivars and seasons, was explained by a combination of two hypotheses: leaf chlorophyll content was limited by the available N resources in controls, but not in salt-stressed plants; and the sodium concentrations were not high enough to cause early leaf senescence and chlorophyll degradation. The growth reductions were attributed to loss of assimilates (mechanisms unknown) that must have occurred after export from the sites of assimilation. The apparent, recurrent losses of assimilates, which were between 8% and 49% according to simulation with the crop model for potential yields in irrigated rice, ORYZA S, might be partly due to root decomposition and exudation. Possibly more importantly, energy-consuming processes, such as osmoregulation, interception of sodium and potassium from the transpiration stream in leaf sheaths and their subsequent storage, drained the assimilate supply.