Upland Rice Research Articles

Heavy metal contamination and potential health risks in upland rice-producing soils of rotational shifting cultivation in northern Thailand

Rotational shifting cultivation (RSC) is commonly practiced in northern Thailand for upland rice cultivation, primarily for household consumption. However, the potential health risks from heavy metal contamination in these soils have not been thoroughly explored. This study aimed to evaluate the contamination of six heavy metals (Arsenic (As), Mercury (Hg), Cadmium (Cd), Lead (Pb), Copper (Cu), and Chromium (Cr)) in upland rice across RSC fields with varying fallow periods and assess the associated health risks from rice consumption. Four RSC fields with 5, 6, 10, and 12-year fallow periods were examined. The RSC-6Y and RSC-12Y fields were used for upland rice cultivation in 2022, while the RSC-5Y and RSC-10Y fields were cultivated in 2023. The geo-accumulation index (Igeo) was calculated, and translocation factors (TF) were assessed for the transfer of heavy metals from soil to straw (TFStraw/Soil), straw to grain (TFGrain/Straw), and soil to grain (TFGrain/Soil). The results indicated that after burning vegetation in the RSC fields, the highest concentrations of Pb, Cr, and Hg were found in the ash. In RSC soils, Cu, Cr, As, Pb, and Hg levels were below reference standards, with Cd undetected. In rice grains, the order of concentration was Pb > Cu > Cr > As, with Hg and Cd undetected. Pb levels in rice grains exceeded the safety threshold. Igeo values indicated no contamination to moderate contamination across sites, with negative Igeo values for Cr and Cu, and zero values for Cd. The TF results showed limited transfer of As, Hg, and Cd from soil to rice plants (TFStraw/Soil < 0.1), but notable transfer for Pb, Cr, and Cu. Pb was readily transferred from soil to grain (TFGrain/Soil), posing a potential health risk. The study highlights potential non-carcinogenic and carcinogenic risks from heavy metal exposure, particularly Pb, and underscores the need for further research to determine contamination sources and mitigation strategies.

Occurrence of plant-parasitic nematodes on rice (Oryza sativa) in Kenya with a focus on Hirschmanniella oryzae

Summary Rice ranks as the third most important staple cereal food crop in Kenya, following maize and wheat. The demand for rice has been increasing at a faster rate than most cereals, occasionally requiring imports to meet local needs. In response, the Kenyan government has been implementing a programme to increase rice production by expanding irrigated lowland rice schemes from 32 988 to 171 676 ha, while increasing rain-fed upland production areas four-fold to 42 000 ha by 2030. However, with continued rice monocropping in irrigated lowland fields and intensification in rain-fed upland ecosystems, there is a growing concern that plant-parasitic nematodes may emerge as a significant problem across rice ecosystems. This study characterised the nematode genera associated with rice in Kenya and assessed their diversity and distribution across rice ecosystems, with a focus on Hirschmanniella species. Eleven nematode genera were identified in both ecosystems, indicating a relatively high diversity. These genera, ranked by prominence, included Hirschmanniella, Hoplolaimus, Pratylenchus, Helicotylenchus, Meloidogyne, Ditylenchus, Trichodorus, Xiphinema, Rotylenchus, Longidorus and Paratylenchus. The family Tylenchidae was also found to be an important component of the nematofauna. Both morphological and molecular analyses confirmed the presence of Hirschmanniella oryzae in irrigated lowland and rain-fed upland rice, which represents the first documented report for Kenya. A notably large molecular variation was also observed for these Kenyan populations on the 18S region, with intraspecific variation up to 10 bp difference. Understanding the diversity, distribution, and species composition of nematodes in rice ecosystems is important for raising awareness among plant protection services, farmers, cooperatives and extension agents about plant-parasitic nematodes and their challenges in rice production. Future research should build on this knowledge to support extensive studies on population dynamics and damage threshold, focusing on local rice cultivars to develop effective management strategies, including breeding programmes and other cultural practices.

Effect of Nano Encapsulated Pendimethalin on Growth Attributes of Rice

Weed infestation is a major problem in upland rice of Kerala. Pendimethalin is a selective pre-emergent herbicide used to control broad-leaved and grassy weeds in rice fields. However, herbicides like pendimethalin often face losses in the agroecosystem through various pathways, reducing their effectiveness and potentially contaminating the environment, including groundwater. Encapsulation of herbicides is an innovative method designed to enhance their efficacy while minimizing environmental contamination, making herbicide application more efficient for weed control. A field experiment was carried out at the Instructional Farm, College of Agriculture, Vellayani, Kerala, India to evaluate the effect of different concentrations of Nano Encapsulated Pendimethalin (NEP) for weed management in upland rice. Synthesis of nano encapsulated pendimethalin was done at Department of Agronomy, College of Agriculture, Vellayani. The study revealed that nano encapsulated pendimethalin had significant influence on growth attributes over normal commercial formulations. Among all the growth parameters Nano Encapsulated Pendimethalin (NEP) with 4% starch aqueous phase at 1.0 kg ha-1 showed comparable result with hand weeding at 15 and 30 Days After Sowing (DAS). The nano encapsulated formulation had a particle size of 486.6 nm and zeta potential of -18 mV.

Root exudation patterns of contrasting rice (Oryza sativa L.) lines in response to P limitation

Main conclusionRice exudation patterns changed in response to P deficiency. Higher exudation rates were associated with lower biomass production. Total carboxylate exudation rates mostly decreased under P-limiting conditions.Within the rhizosphere, root exudates are believed to play an important role in plant phosphorus (P) acquisition. This could be particularly beneficial in upland rice production where P is often limited. However, knowledge gaps remain on how P deficiency shapes quality and quantity of root exudation in upland rice genotypes. We therefore investigated growth, plant P uptake, and root exudation patterns of two rice genotypes differing in P efficiency in semi-hydroponics at two P levels (low P = 1 µM, adequate P = 100 µM). Root exudates were collected hydroponically 28 and 40 days after germination to analyze total carbon (C), carbohydrates, amino acids, phenolic compounds spectrophotometrically and carboxylates using a targeted LC–MS approach. Despite their reported role in P solubilization, we observed that carboxylate exudation rates per unit root surface area were not increased under P deficiency. In contrast, exudation rates of total C, carbohydrates, amino acids and phenolics were mostly enhanced in response to low P supply. Overall, higher exudation rates were associated with lower biomass production in the P-inefficient genotype Nerica4, whereas the larger root system with lower C investment (per unit root surface area) in root exudates of the P-efficient DJ123 allowed for better plant growth under P deficiency. Our results reveal new insights into genotype-specific resource allocation in rice under P-limiting conditions that warrant follow-up research including more genotypes.

Review of Drought Stress and Seed Priming Effects on Upland Rice Yield and Longevity

Unequal plant stand and poor germination are major constraints in seeds under areas which receive erratic and low rainfall. Seed priming has emerged as a crucial strategy to enhance the biochemical, physiological, and ecological resilience of seeds and seedlings. Employing suitable priming methods at different developmental stages can significantly improve drought tolerance in plants. Research indicates that the primary factors leading to seed deterioration are the combined effects of low temperatures and moisture levels, which trigger abnormal biochemical and physiological responses. Seed priming techniques show promise due to their simplicity and adaptability in local agricultural practices. However, one of the challenges associated with primed seeds is their relatively short storage lifespan. This review aims to explore the biochemical, physiological, and molecular aspects of rice seed priming while proposing innovative techniques to extend seed longevity, improve stand establishment, and increase overall yield. Furthermore, understanding the molecular mechanisms underlying seed priming can lead to the development of more effective priming protocols. This could ultimately contribute to sustainable agricultural practices in regions vulnerable to climate variability.

Effect of Seed Priming on Adaptive Morphological Traits of Anaerobic Germination Tolerant Upland Rice Genotypes

Effect of Seed Priming on Adaptive Morphological Traits of Anaerobic Germination Tolerant Upland Rice Genotypes

The Threat of the Fall Armyworm to Asian Rice Production Is Amplified by the Brown Planthopper.

The recent invasion of the fall armyworm (FAW) into Asia not only has had a major impact on maize yield but is feared to also pose a risk to rice production. We hypothesized that the brown planthopper (BPH) may aggravate this risk based on a recently discovered mutualism between the planthopper and the rice striped stem borer. Here we show that BPH may indeed facilitate a shift of FAW to rice. FAW females were found to strongly prefer to oviposit on BPH-infested rice plants, which emitted significantly elevated levels of five volatile compounds. A synthetic mixture of these compounds had a potent stimulatory effect on ovipositing females. Although FAW caterpillars exhibited relatively poor growth on both uninfested and BPH-infested rice, a considerable portion completed their development on young plants. Moreover, FAW were found to readily pupate and survive in exceedingly moist soils typical for rice cultivation, further highlighting FAW's potential to switch to rice. We conclude that BPH, by changing the bouquet of volatiles emitted by rice plants, may greatly facilitate this switch. These findings, together with a current increase of nonflooded upland rice in Asia, warrant careful monitoring and specific control measures against FAW to safeguard Asian rice production.

Improvement of growth and nutrient uptake of upland rice grown on degraded acid soil with the application of liquid organic fertilizer

This research aimed to determine the effectiveness of several types of liquid organic fertilizer (LOF) derived from plant waste and the dose of P fertilizer on the growth and yield of upland rice on degraded acid soil. The treatments consisted of two factors. The first factor (A) was several types of LOF consisting of A1 (control), A2 (LOF containing isolates of P-solubilizing bacteria), A3 (LOF-banana waste), and A4 (A2+A3). The second factor (B) was fertilizer doses consisting of B1 (50% of the recommended dose of P fertilizer), B2 (75% of the recommended dose of P fertilizer), and B3 (100% of the recommended dose of P fertilizer). The treatment combinations were arranged in a factorial randomized block design with three replications. The research results showed that applying either LOF-banana waste or the mixture of LOF-banana waste and LOF-containing isolates of P-solubilizing bacteria improved plant height, the number of tillers, and N and P uptake by the plant. The rice grain yields among the treatments were not significantly different, but the highest rice grain yield (139.8 g/pot) was obtained at the treatment of the mixture of LOF-P isolate + LOF-banana waste (A2+A3 treatments). The 75% of the recommended dose of P fertilizer was not significantly different from 100% P fertilizer with LOF on growth and yield upland rice and nutrient uptake by the plant.

Tolerance of local gogo rice sprouts under salinity stress conditions

The expansion of rice planting areas in the future needs to be carried out outside Java, as fertile land in Java is shrinking due to land conversion. Most of the land outside Java consists of marginal land, such as areas with high salinity. High salinity levels in the soil cause a decrease in plant germination, growth, and production. The research aimed to examine the tolerance of each cultivar at each level of NaCl concentration, to obtain cultivars that were tolerant to salinity stress, and to determine the NaCl concentration that suppresses the germination of local upland rice. The research was structured using a completely randomized design with a two-factor factorial pattern. The first was the six upland rice cultivars, namely, dongan, jahara, Pulu Konta, pomegranate, kalendeng, and pulu tau leru, while the second factor was the NaCl concentration consisting of 0%, 0.2%, 0.4%, 0.6%, 0.8% and 1%. Thus, there were 36 experimental units, which were repeated three times so that there were 108 experimental units. The results of the research showed that there was no interaction with all germination variables; cultivar and concentration had a significant effect on maximum growth potential, germination capacity, germination time, plumule length, radicle length and dry weight of sprouts, while cultivar affected the wet weight of sprouts. Kalendeng has a high salinity tolerance. The use of NaCl concentrations of up to 0.6% has been able to reduce the germination capacity of local upland rice. The conclusion of the research showe that there was no interaction between all germination variables.

Upland rice retains genetic elements conferring drought adaptation

Upland rice retains genetic elements conferring drought adaptation

Enhancing Growth of Upland Rice in Low-Phosphorus Soil by Leveraging Root Morphological Traits

Low phosphorus (P) in the upland ecosystems negatively, influence rice growth and causes significant yield losses. In the present study, 9 upland rice genotypes were screened to identify root traits that support the growth in low P soil in a cement tank. Rice genotypes showed significant (p = ≤ 0.05) variation for number of root tips (NRT), number of root branching points (NBP), total root length (TRL), whole root network area (NA), average root diameter, root volume (RV), root surface area (RSA), first order root length (FORL), and second order root length (SORL). BW01 and ITA01 recorded the highest NRT, NBP, TRL, RV, NA, RSA, FORL and SORL while NERICA04 had the lowest representing 5.8, 8.0, 7.6, 6.8, 9.0, 5.8, and 9.3 differences in these traits under low P soil. NRT significantly positively correlated with NBP, TRL, NA, RV, RSA, FORL indicating the role of different root traits in foraging for soil nutrients. The principal component analysis (PCA) showed that the NRT, NBP, TRL, RSA and SORL are important and effective root traits for selection in rice breeding under low P soil supply. BW01 and ITA01 recorded well developed root system indicating that they are P-efficient than P-inefficient NERICA04 under low P soil conditions. Therefore, BW01 and ITA01 can targeted for cultivation in P deficient soils and also used as donor of novel root traits to improve P-inefficient rice cultivars.

Scouting rice (Oryza sativa L.) landraces for moisture stress tolerance using morphometric diversity analysis

Climate-change is a major threat to sustainable agriculture. Rice is one of the staple food grains that sustain 2/3rd of global population. Therefore, developing climate-resilient rice genotypes to combat moisture stress and other climate change factors are most important to address the challenges posed by climate change. The vast availability of genetic variance among the rice genotypes for different traits favours the selection of desirable donor parents. A field investigation was carried out to characterize 21 traditional rice landraces under induced moisture stress in 2 environments including induced moisture stress (S) and non-stress (NS). The response to the varied level of environments was observed in terms of biometric and yield parameters followed by multivariate analysis and variability analysis. The study revealed higher phenotypic-coefficient of variation (PCV) and genotypic-coefficient of variation (GCV) for plant height and single plant yield in both environments. High heritability was also recorded in the moisture stressed environment for plant height (98.63 %), single plant yield (98.19 %) and productive tillers (95.12 %), whereas under NS, the heritability is more for single plant yield only (99.56 %). The genotypes formed nine clusters under the S environment, based on the Euclidean distance, of which the three CMS lines segregated in cluster III distinctly. The principal component analysis exhibited three principal components with a cumulative variance of 86.13 % and 86.40 % in the NS and S environments respectively. The traits such as days to 50 % flowering, panicle height, panicle length, grains per panicle, productive tillers, thousand-grain weight and single plant yield were the positive contributors. Spikelet fertility (%) and harvest index were positively correlated with seed yield per plant. Path-coefficient analysis was significant for grain yield, harvest index, spikelet fertility, pollen fertility and plant height and positively influenced by productive tillers plant-1. The study concluded the prospect of using Mattaikar, Rajalakshmi, Mallikar and Kuliyadichan as potential donors for developing upland rice with moisture stress resilience.

The OsNAC41-RoLe1-OsAGAP module promotes root development and drought resistance in upland rice

Drought is a major environmental stress limiting crop yields worldwide. Upland rice (Oryza sativa) has evolved complex genetic mechanisms for adaptative growth under drought stress. However, few genetic variants that mediate drought resistance in upland rice have been identified, and little is known about the evolution of this trait during rice domestication. In this study, using a genome-wide association study we identified ROOT LENGTH 1 (RoLe1) that controls rice root length and drought resistance. We found that a G-to-T polymorphism in the RoLe1 promoter causes increased binding of the transcription factor OsNAC41 and thereby enhanced expression of RoLe1. We further showed that RoLe1 interacts with OsAGAP, an ARF-GTPase activating protein involved in auxin-dependent root development, and interferes with its function to modulate root development. Interestingly, RoLe1 could enhance crop yield by increasing the seed-setting rate under moderate drought conditions. Genomic evolutionary analysis revealed that a newly arisen favorable allelic variant, proRoLe1−526T, originated from the midwest Asia and was retained in upland rice during domestication. Collectively, our study identifies an OsNAC41-RoLe1-OsAGAP module that promotes upland rice root development and drought resistance, providing promising genetic targets for molecular breeding of drought-resistant rice varieties.

Impact of 240 g/L glyphosate IPA on weed control and upland rice (Oryza sativa L.) growth and yield in a no-tillage system

Glyphosate IPA 240 g/L herbicide is known as one of the effective chemical solutions in weed control, especially in no-tillage systems. No-tillage systems offer advantages in upland rice cultivation by reducing soil damage and production costs. However, the main challenge in the application of no-tillage systems is the presence of pre-planting weeds that can compete with plants in the absorption of growth factors such as nutrients, light, and water. This experiment aims to test herbicide doses that effectively suppress weed growth and optimize the growth and yield of upland rice with the no-tillage system. The experiment was conducted from December 2023 to April 2024 at Ciparanje Farm, Faculty of Agriculture, Padjadjaran University, Jatinangor District, Sumedang Regency, West Java Province, Indonesia. The experiment used Randomized Block Design (RBD), consisting of 7 treatments, each repeated four times. The treatments consisted of 5 doses of glyphosate IPA 240 g/L herbicide 2.00, 3.00; 4.00, 5.00; 6.00 L/ha with no-tillage system; manual weeding; and control with perfect tillage system. Experimental results showed that glyphosate IPA 240 g/L herbicide at a dose of 3.00 - 6.00 L/ha with the no-tillage system can be used to replace the perfect tillage system because it can suppress the growth of broadleaf weeds, namely Ageratum conyzoides, Cleome rutidosperma, Mollugo pentaphylla and Synedrela nodiflora, and grass Digitaria ciliaris. No phytotoxicity symptoms were found, and had a favorable effect on rice plant growth regarding population size and tillers. The yield of rice plants with the highest milled dry grain yield was 4.45 t/ha.

Substitutive Effects of Upland Rice and Soybean Plant Populations on the Performance of the Component Crops in Intercropping System

Substitutive Effects of Upland Rice and Soybean Plant Populations on the Performance of the Component Crops in Intercropping System

PERTUMBUHAN DAN HASIL TANAMAN PADI GOGO (Oryza sativa L.) PADA TANAH PODSOLIK (ULTISOL) YANG DIAPLIKASIKAN ZEOLIT FLY ASH

The low productivity of upland rice on Podzolic (Ultisol) soil is caused by various constraints including low pH, the content of macronutrient N, P, K, Ca and Mg, BS and CEC were low, solubility and high Al saturation, high P fixation, delicate to erosion and water availability were low. Applied of zeolite synthesized from coal fly ash with high CEC is expected to overcome these constraints. The high negative charge on zeolite contributes to increasing soil absorption of nutrients provided or dissolved from soil minerals and decomposition of organic matter. The study was conducted experimentally using a completely randomized design, zeolite fly ash as the treatment consisting of 6 levels (0, 100, 150, 200, 250 and 300 kg ha-1) each repeated 3 times. The results showed that the application of zeolite fly ash dose 100-300 kg.ha-1 tends increased the plant height, filled grain number per panicle, the percentage of filled grain and 1000 grain weight compared without zeolite application and the highest increased showed in the number of maximum tillers and productive tillers and weight of milled dry grain per clump was obtained at a dose of 200 kg.ha-1 compared without zeolite is 45, 107 and 106% respectively.

Higher rice productivity and lower paddy nitrogen loss with optimized irrigation and fertilization practices in a rice-upland system

Intermittent irrigation and controlled-release fertilizers are considered effective practices for rice growth; however, their combined effects on nitrogen (N) loss from intensified agricultural lands remain unclear. Here, a two-year field experiment was conducted using two irrigation regimens (flooded irrigation, FI; controlled irrigation, CI) and two fertilizer types (conventional urea, CU, split applied; controlled-release blend fertilizer, CRBF, one-time basal applied) to investigate their effects on N turnover in rice upland systems. The results demonstrated that CI not only saved 56.7 % of irrigation water compared to FI but also increased rice yield (5.3 %) and N use efficiency (7.8 %). The significant reduction in water input and soil water content for the CI led to lower N leaching (47.5 %) and N runoff (20.2 %) than for the FI. In contrast, N2O emissions increased by 27.8 % under CI compared with FI. CRBF reduced NH3 volatilization by 18.8 % and improved N use efficiency by 14.0 %, due to decreased N diffusion from the soil to surface water compared to CU. However, the N runoff of the CRBF was 23.8 % greater than that of the CU. The CI-CRBF improved the rice yield by 6.3 % and decreased N loss (22.3 %) by reducing NH3 volatilization (21.4 %) and N leaching (46.9 %). The findings suggest CI-CRBF to be an eco-friendly and lightly simplified pattern in rice upland systems, with higher rice productivity and lower paddy N loss.

Pengaruh Jenis Biochar dan Jarak Tanam Terhadap Pertumbuhan dan Hasil Padi Gogo (Oryza sativa L.)

Upland rice has the potential to be cultivated on land that has limited water. Plant spacing needs to be done as a strategy so that upland rice can absorb light and water optimally. Apart from that, biochar can be used to improve soil properties so that it is suitable for supporting the growth of upland rice plants on dry land. The study aims to examine the response of biochar application and plant spacing on the growth and yield of upland rice. The study was conducted in the experimental garden of the Faculty of Agriculture, Universitas Perjuangan Tasikmalaya at an altitude of 359 meters above sea level. This study used a factorial Randomized Completely Block Design (RCBD). The first factor is a type of biochar consisting of coconut shells and rice husks charcoal. The second factor is the plant spacing consisting of 20 x 20 cm and 30 x 30 cm. The results showed that there was no interaction between the two treatments on the growth and yield of upland rice. The application of biochar had a significant effect on the number of panicles per hill, while plant spacing had a significant effect on the root length, root wet weight, 1.000 seed weight, and yield. The coconut shell was able to increase the number of panicles per hill, while the wider plant spacing caused an increase in root length, root wet weight, 1.000 seed weight, and yield. In general, the application of biochar can improve crop yields, while regulating the plant spacing has the potential to increase the growth and yield of upland rice.

Aplikasi Ekstrak Mimosa invisa L. dan Pupuk NPK Dosis Rendah dalam Pengendalian Hama dan Patogen Padi Gogo

This study aimed to determine the effect of Mimosa invisa L. weed extract application and a low dose of NPK fertilizer on the intensity of pest attack and pathogen infection on upland rice. This research has been done using Split Plot Design with 3 replications. The main plot was the dose of NPK fertilizer (50% and 100% NPK). The subplot was the concentration of weed extract (0, 1.25, 1.67, 2.5, and 5% concentrations). The variables observed include the intensity of grasshopper and case worm attack, Cercospora sp. that causes brown spots, and Xanthomonas oryzae pv. oryzae that causes bacterial leaf blight. The results showed that the application of weed extract under a low dose (50% NPK) has not been able to suppress the intensity of grasshopper and case worm attacks, and the intensity of the pathogen causes brown spots and bacterial leaf blight. However, 2,5% and 5% concentrations of weed extract can potentially suppress pathogen infection that causes brown spots on upland rice. Keywords: grasshopper, brown spots, Mimosa invisa L.weed extract, case worm, bacterial leaf blight, NPK fertilizer

Effect of localized fertilizer application on deep root development during early growth in upland rice under upland condition

ABSTRACT The effects of localized fertilizer (LF) application on changes in root system architecture (RSA) of upland rice seedlings under upland condition were evaluated, and root traits important for deep root development were identified using three root box experiments (Exps). Fertilizer was homogeneously mixed and broadcasted on the soil surface in two control treatments, while in three LF treatments, it was point-placed at 2.5, 7.5 and 12.5 cm below the soil surface. Nitrogen (N) fertilizer in Exp. 1, phosphorus (P) fertilizer in Exp. 2 and compound fertilizer with nitrogen, phosphorus and potassium (NPK) in Exp. 3 were used to compare the effects of LF. Localized N and NPK application altered the RSA through root proliferation and increasing root length percentage around the fertilizer-applied area, whereas localized P application had no effect on both root and shoot development. Deep root and shoot development were decreased with localized NPK application compared to homogeneously mixed control treatment but were maintained with localized N application, when applied at deeper soil depths. Furthermore, the increase in deep root length (DRL) was closely related to the increase in both total root length (TRL) and deep root length ratio (DRR). DRR increased with TRL in Exps. 2 and 3, while it was independent from TRL in Exp. 1, suggesting that DRL can be promoted by increasing DRR regardless of TRL. These results showed that localized N application at deeper soil depths could modify RSA of upland rice seedlings grown under upland condition without affecting shoot growth.