Rice Plant Height Research Articles

Evaluation of Trinexapac‐Ethyl and Nitrogen Management to Minimize Lodging in Rice

Rice (Oryza sativa L.) is an important crop in the midsouthern United States. However, some high‐yielding cultivars are highly susceptible to lodging. The plant growth regulator, trinexapac‐ethyl (TE), has been shown to decrease lodging in upland cereal crops, but data are scarce that demonstrate rice response to TE. The objective of this study was to determine the effect of TE on rice plant height, lodging, and grain yield. Experiments were established at multiple locations during the 2012 and 2013 growing seasons in Mississippi. Trinexapac‐ethyl was applied to a lodging‐susceptible rice cultivar at 12, 24, and 48 g a.i. ha−1 at two timings: panicle differentiation (R1) and R1 + 14 d. Rice response to TE was determined for rice that received 100% of N applied at V3 and rice that received a two‐way split N strategy (75% N at V3 and 25% at R1). On both clay and silt‐loam soils all rates of TE reduced plant height and lodging compared to nontreated rice. The effect of TE on rice grain yield was variable. On silt‐loam soils 12 g a.i. ha−1 TE resulted in rice grain yield similar to nontreated rice when applied at R1, but decreased grain yield when applied to rice at R1+ 14 d. The 48 kg a.i. ha−1 rate decreased rice grain yield on both soil textures. The results of this study indicate that trinexapac‐ethyl may be a useful tool to manage lodging, but further research is needed refine TE use guidelines in rice. Trinexapac‐ethyl decreased rice plant height and lodging on both clay and silt loam soils. Trinexapac‐ethyl at 12 g a.i. ha−1 did not decrease grain yield when applied at panicle differentiation on silt loam soils. Grain yield response to trinexapac‐ethyl varied by soil texture and N management strategy.

Polycomb Protein OsFIE2 Affects Plant Height and Grain Yield in Rice.

Polycomb group (PcG) proteins have been shown to affect growth and development in plants. To further elucidate their role in these processes in rice, we isolated and characterized a rice mutant which exhibits dwarfism, reduced seed setting rate, defective floral organ, and small grains. Map-based cloning revealed that abnormal phenotypes were attributed to a mutation of the Fertilization Independent Endosperm 2 (OsFIE2) protein, which belongs to the PcG protein family. So we named the mutant as osfie2-1. Histological analysis revealed that the number of longitudinal cells in the internodes decreased in osfie2-1, and that lateral cell layer of the internodes was markedly thinner than wild-type. In addition, compared to wild-type, the number of large and small vascular bundles decreased in osfie2-1, as well as cell number and cell size in spikelet hulls. OsFIE2 is expressed in most tissues and the coded protein localizes in both nucleus and cytoplasm. Yeast two-hybrid and bimolecular fluorescence complementation assays demonstrated that OsFIE2 interacts with OsiEZ1 which encodes an enhancer of zeste protein previously identified as a histone methylation enzyme. RNA sequencing-based transcriptome profiling and qRT-PCR analysis revealed that some homeotic genes and genes involved in endosperm starch synthesis, cell division/expansion and hormone synthesis and signaling are differentially expressed between osfie2-1 and wild-type. In addition, the contents of IAA, GA3, ABA, JA and SA in osfie2-1 are significantly different from those in wild-type. Taken together, these results indicate that OsFIE2 plays an important role in the regulation of plant height and grain yield in rice.

Effect of Compost Combination on Methane Emission in Undisturbed Acid Sulphate soil in South Kalimantan of Indonesia

A greenhouse experiment was conducted to examine the cumulative methane (CH4) emission in paddy soils and correlation with soil redox potential (Eh), soil pH and plant growth. The experiment was arranged in two factorial randomized block designs with three replications. The first factor was a kind of of organic matter, i.e. without organic matter (T0), combination of 50% of composted straws and 50% composted rush weed (T1), combination of 30% of composted straws and 30% composted rush weed and 40% composted cattle manure (T2) and the second factor was the management of water that was continuously flooded and leaching. The methane emission was measured in South Kalimantan using the chamber and gas chromatogram technique. The results showed methane emission in undisturbed acid sulphate soil ranged from 0.05 to 0.32 mg CH4.m-2.minute-1 during the rice-growing season. The methane emission from the paddy soil were lower when the paddy was drained than when it was flooded. Correlation analysis showed a negative relation between methane emission and soil redox potential (Eh) and soil pH in both water management. The rice plant height and number of buds has positively correlation with methane emission with coeffecient correlation of r=0.84**(P<0.0001) and r=0.64**(P=0.004), respectively. Normal 0 false false false IN X-NONE X-NONE [ How to Cite : Wahida A and A Maas. 2015. Effect of Compost Combination on Methane Emission in Undisturbed Acid Sulphate soil in South Kalimantan of Indonesia. J Trop Soils 20: 135-141. Doi: 10.5400/jts.2015.20.3.135 ]

How effective are disturbance – tolerant, agroecosystem – nesting ant species in improving soil fertility and crop yield?

Study of the abundance, diversity and nest densities of agroecosystem-inhabiting ant species, in fallow, freshly tilled and cultivated farmers’ fields revealed that Pheidole latinoda had highest abundance, nest density and disturbance-tolerance ability. Thirty-one arthropod morphospecies belonging to 12 orders were recorded in the nest entrance rim debris piles of this ant species. Hence, P. latinoda was selected to study the impact of nest rim debris soil on soil fertility and yield of two common crops, rice and tomato, widely cultivated in the Indo-Gangetic plains of India. Experimental field studies revealed that ant-related enrichment results in significant increase of the C, N and P contents of the bulk soil and a doubling of the soil microbial biomass. The soil enrichment significantly enhanced the yield of both the crop plants in a dose-dependent manner. A significant positive correlation was found between the ecophysiological traits including the specific leaf area, plant height and total plant weight of both rice and tomato plants, and the soil chemical constituents i.e. total C, N, P, NH4-N, NO3-N, microbial biomass C, N and P. The ecosystem engineering activities of P. latinoda ant colonies apparently enriched the soil via the nutrient cycling activities of the debris arthropods, on the externally discarded organic refuse. Since P. latinoda increases productivity via increase in soil fertility and also has the potential to suppress insect pests of crops, conservation of such ant species could enhance agricultural sustainability, through multiple pathways.

Dissection of genetic architecture of rice plant height and heading date by multiple-strategy-based association studies.

Xieyou9308 is a certified super hybrid rice cultivar with a high grain yield. To investigate its underlying genetic basis of high yield potential, a recombinant inbred line (RIL) population derived from the cross between the maintainer line XieqingzaoB (XQZB) and the restorer line Zhonghui9308 (ZH9308) was constructed for identification of quantitative trait SNPs (QTSs) associated with two important agronomic traits, plant height (PH) and heading date (HD). By re-sequencing of 138 recombinant inbred lines (RILs), a total of ~0.7 million SNPs were identified for the association studies on the PH and HD. Three association mapping strategies (including hypothesis-free genome-wide association and its two complementary hypothesis-engaged ones, QTL-based association and gene-based association) were adopted for data analysis. Using a saturated mixed linear model including epistasis and environmental interaction, we identified a total of 31 QTSs associated with either the PH or the HD. The total estimated heritability across three analyses ranged from 37.22% to 45.63% and from 37.53% to 55.96% for the PH and HD, respectively. In this study we examined the feasibility of association studies in an experimental population (RIL) and identified several common loci through multiple strategies which could be preferred candidates for further research.

Effect of pre-emergence herbicides and timing of soil saturation on the control of six major rice weeds and their phytotoxic effects on rice seedlings

The study evaluated the effects of pre-emergence herbicides and their rates [oxadiazon (0.5 and 1 kg ai ha−1), pendimethalin (1 and 2 kg ai ha−1), and pretilachlor with safener (0.6 kg ai ha−1)], and time of soil saturation establishment after herbicide application [1, 3, 5, and 7 days after spray (DAS)] in controlling the six major rice weeds, and their phytotoxic effects on rice seedling growth. All herbicides provided 100% control of Echinochloa colona, Echinochloa crus-galli, Leptochloa chinensis, Cyperus iria, and Amaranthus spinosus. Murdannia nudiflora was 100% controlled by oxadiazon and pretilachlor with safener, but poorly controlled (22–75%) by pendimethalin. Pendimethalin at 2 kg ai ha−1 was more effective than at 1 kg ai ha−1 in reducing the biomass of the stem, leaf, and root of M. nudiflora irrespective of timing of soil saturation. Rice plant height was reduced to a maximum (77–96%) by pendimethalin at 2.0 kg ai ha−1 followed by oxadiazon at 1.0 kg ai ha−1 (38–70%) compared to the non-treated control. In contrast, the tallest rice plants were observed in the non-treated control and those treated with pretilachlor with safener which had 80–100% rice plant survival. The lowest rice plant survival of 0, 6, 7, and 16% was found in the soil applied with pendimethalin at 2 kg ai ha−1 and saturated at 1, 3, 5, and 7 DAS, respectively, which was followed by oxadiazon at 1 kg ai ha−1. All herbicides except pretilachlor with safener reduced SPAD values with early soil saturation, which improved with delay in soil saturation timing. Pendimethalin at 2 kg ai ha−1 reduced the SPAD values of rice plants by 100–164% relative to the non-treated control and produced the highest phytotoxicity symptoms. Pendimethalin also reduced rice shoot biomass more than oxadiazon, which was compounded by early soil saturation after herbicide application. Pretilachlor with safener was the only herbicide that exhibited low phytotoxic symptoms on rice plants and did not reduce leaf, stem, root, and shoot biomass of rice. Percent reduction in rice leaf, stem, root, and shoot biomass by the different herbicides was in the order of pendimethalin 2 > oxadiazon 1 > pendimethalin 1 > oxadiazon 0.5 > pretilachlor with safener 0.6 kg ai ha−1. Each herbicide treatment reduced rice growth parameters as soil saturation was delayed in the order of 1 DAS > 3 DAS > 5 DAS > 7 DAS. The study suggests that soil water content and herbicide rates are important factors in influencing herbicide phytotoxicity in rice. The application of herbicides should be avoided when the soil is too wet, and irrigation should be delayed at least one week after herbicide application.

Rice husk biochar application to paddy soil and its effects on soil physical properties, plant growth, and methane emission

The objective of this study was to investigate the effects of the application of rice husk biochar on selected soil physical properties, rice growth, including root extension, and methane (CH4) emissions from paddy field soil. Three replication experiments were conducted using outdoor pot experiments utilizing commercial rice husk biochar mixed with paddy soil at a rate of 0 (control), 2, and 4 % (weight biochar/weight soil) in which the rice was cultivated for 100 days under a continuously flooded condition. The physical properties of soils were analyzed before and after the growing periods. Some parameters of rice growth and CH4 emissions of paddy soils were monitored weekly during the experiment. Root extension was also analyzed after harvesting. The experiments showed that the application of rice husk biochar improved the physical properties of paddy soils. It led to a decrease in bulk density and an increase in saturated hydraulic conductivity, including the total pore volume as well as the available soil water content. The shoot height of rice plants was significantly higher in soil amended with 4 % biochar than that in the control soil. However, other plant growth parameters and root extension were only slightly affected by the application. It was also found that amending soil with biochar led to a reduction of the total CH4 emissions by 45.2 and 54.9 % for an application rate of 2 and 4 %, respectively, compared with the control. Our results showed that the higher the application rate, the stronger the effect of biochar was observed. More research is still necessary for a better understanding of the underlying mechanisms.

The pleiotropic ABNORMAL FLOWER AND DWARF1 affects plant height, floral development and grain yield in rice.

Moderate plant height and successful establishment of reproductive organs play pivotal roles in rice grain production. The molecular mechanism that controls the two aspects remains unclear in rice. In the present study, we characterized a rice gene, ABNORMAL FLOWER AND DWARF1 (AFD1) that determined plant height, floral development and grain yield. The afd1 mutant showed variable defects including the dwarfism, long panicle, low seed setting and reduced grain yield. In addition, abnormal floral organs were also observed in the afd1 mutant including slender and thick hulls, and hull‐like lodicules. AFD1 encoded a DUF640 domain protein and was expressed in all tested tissues and organs. Subcellular localization showed AFD1‐green fluorescent fusion protein (GFP) was localized in the nucleus. Meantime, our results suggested that AFD1 regulated the expression of cell division and expansion related genes.

Studies on the Ecological Adaptability of Growing Rice with Floating Bed on the Dilute Biogas Slurry.

This study aimed to explore the ecological adaptability and the possibility of growing rice with floating bed on the dilute biogas slurry. The results of the experiments show that the growth stage, rice plant height, and rice yield and quality were significantly affected by multiple dilutions; rice plants cultivated with 45 multiple dilutions had better ecological adaptability than others. In the 45 multiple dilutions' group, the yield of rice was 13.3 g/bucket (8 rice plants), milled rice rate was 63.1%, and the content of crude protein in the rice was 6.3%. The concentrations of heavy metals in the rice cultivated with 30 multiple dilutions' slurry, such as total lead, cadmium, mercury, chromium, and arsenic, were all below the national standard. The study shows that it is possible and safe to cultivate rice plants with no soil but diluted biogas slurry. In the experiments, the yield, milled rice rate, and crude protein of the rice cultivated with slurry were not as much as those of rice cultivated with regular way in soil. This study provides the basic theoretical support for the development of biogas projects and the potential achievement of organic farming in special agricultural facilities and circular economy.

Effect of Controlled-release Nitrogen Fertilizer on Methane Emission from Paddy Field Soil

An experimental study was conducted to investigate the effect of Controlled Release Nitrogen Fertilizer on CH4 emission from a rice paddy field soil using pot experimental setup. The experiment is designed with three fertilizer types, i.e., controlled-release nitrogen fertilizer (Neem oil coated urea) and urea (U) and organic fertilizers like Gliricidia sepium, cowpea, Farmyard manure etc. There are two rice cultivars Uma and Jyothy were used for the pot experiment. Each experiment replicate triply. Methane flux was measured at different growth stages for the two rice cultivar by one-time application of CRNF compared with Urea and Organic fertilizer. The methane emission was noted at different rice growth stages. Finally the total CH4 emission from the cultivar is also calculated. CH4 emission was decreased at vegetative stage, gradually increased at reproductive stage and decreased at grain filling to maturity. Methane emission was higher from Heading to flowering, accounting for 35.21% to 41.53% of total cumulative emission. CRNF significantly affect the biometric characters like tiller number, plant height, biomass, and yield in rice by using CRNF. Rice yields increased by 11.43 and 11.11% for Uma and Jyothy rice respectively.

Influence of charcoal-based soil amendments on growth and nutrient uptake of rice (Oryza sativa) in Cadmium contaminated soil

Cadmium contamination in paddy soils contributes to Cd toxicity and health risk to humans through consumption of Cd-contaminatedrice. The potential of charcoal-based soil amendment in alleviating cadmium (Cd) toxicity in rice grown in paddy soil with low nitrogenavailability was assessed in order to identify strategies to curve the problems of Cd contamination in rice. A pot culture experiment wasconducted using a Cd-spiked soil with treatment combinations involving two types of charcoal amendments: carbonized rice hull (CRH)and wood charcoal (WC); and three levels of Cd concentration (0, 10 and 20 mg kg-1). CRH and WC amendments reduced the dry matteryield, plant height, tiller number and chlorophyll-SPAD value of rice in the Cd-contaminated soil. CRH and WC amendments reduced thesoluble N but enhanced the residual N, water soluble and exchangeable K, Mg, Ca and Si in soil. The Cd2+ in soil solution was significantly(p<0.01) reduced by CRH and WC which resulted to significantly lower (p<0.01) Cd uptake by rice plants compared to soil withoutamendments. CRH was more effective than WC in lowering Cd availability and uptake by rice plants which could be attributed to thehigher surface area of CRH compared to WC. Overall, CRH and WC decreased Cd availability by increasing the pH and providing additionalsorption sites for Cd which resulted in lower Cd concentration and uptake of rice plants.

EFFECTS OF BLUE LIGHT AND PACLOBUTRAZOL ON SEED GERMINATION, VEGETATIVE GROWTH AND YIELD OF BLACK RICE (Oryza sativa L. 'Cempo Ireng')

Black rice (Oryza sativa L. 'Cempo Ireng') is one of local rice varieties in Sleman Regency, Yogyakarta. The black color is caused by high anthocyanin content which is important source of antioxidant. The cultivation of black rice is still limited due to its tall phenotype, long vegetative stage and low productivitycompared to white rice. Paclobutrazol is a growth retardant causing dwarfing in several crop plants and reducing lodging. Blue light can improve plant quality. This research was aimed to evaluate the effect of blue light and paclobutrazol on seed germination, vegetative growth and yield of black rice. The results showed that the average of seed germination as well as the activity of α-amylase of seeds subjected to blue light were lower compared to those subjected to sunlight; however, paclobutrazol concentrations did not affect seed germination percentage. The height of rice plants treated with paclobutrazol decreased in accordance with the increase of paclobutrazol concentration. Chlorophyll content and tiller numbers increased by paclobutrazol treatment of 12.5 ppm. Nitrate reductase activity was higher in rice seedlings subjected to blue light compared to those subjected to sunlight. Iron (Fe) content of rice plants treated with 25 or 50 ppm paclobutrazol increased compared to control. It was concluded that paclobutrazol application of 12.5 ppm already reduced plant height. The higher concentration of paclobutrazol applied the greater reduction on plant height was observed. Blue light treatment applied during black rice seed germination slightly reduced germination percentage and α-amylase activity in the germinated seeds. However, blue light treatment combined with paclobutrazol application during black rice seed germination increased chlorophyll content, tiller numbers and Fe content in black rice grain.

Espaçamento e adubação nitrogenada afetando o desenvolvimento do arroz de terras altas sob plantio direto

RESUMOA produtividade de grãos do arroz é resultante da interação entre o ambiente e o cultivar utilizado. Entre os fatores que influenciam essa produtividade estão o arranjo das plantas no campo e a adubação nitrogenada. O objetivo deste trabalho foi determinar os efeitos do espaçamento entre fileiras e da adubação nitrogenada na altura e acamamento de plantas, nos componentes de produção e produtividade e na qualidade industrial de grãos de arroz de terras altas, cultivado no sistema plantio direto. O experimento foi desenvolvido durante a safra agrícola 2010/2011, em condições de campo, no município de Selvíria, MS. O delineamento experimental foi em blocos completos casualizados, no esquema fatorial 2 x 4, com quatro repetições. Os tratamentos constaram de combinações entre os espaçamentos entre fileiras (0,35 e 0,50 m) e as doses de N aplicadas na semeadura (0, 40, 80 e 120 kg ha-1). O menor espaçamento entre fileiras condicionou menor altura de plantas de arroz, maior número de panículas m-2, maior fertilidade das espiguetas e consequentemente maior produtividade de grãos de arroz. O incremento das doses de N na semeadura proporcionou maior altura e acamamento de plantas de arroz, ocasionando redução da produtividade e da massa hectolítrica de grãos da cultura. Espaçamento entre fileiras e nitrogênio não alteram a qualidade de grãos do arroz.

Map-Based Cloning of Seed Dormancy1-2 Identified a Gibberellin Synthesis Gene Regulating the Development of Endosperm-Imposed Dormancy in Rice.

Natural variation in seed dormancy is controlled by multiple genes mapped as quantitative trait loci in major crop or model plants. This research aimed to clone and characterize the Seed Dormancy1-2 (qSD1-2) locus associated with endosperm-imposed dormancy and plant height in rice (Oryza sativa). qSD1-2 was delimited to a 20-kb region, which contains OsGA20ox2 and had an additive effect on germination. Naturally occurring or induced loss-of-function mutations of the gibberellin (GA) synthesis gene enhanced seed dormancy and also reduced plant height. Expression of this gene in seeds (including endospermic cells) during early development increased GA accumulation to promote tissue morphogenesis and maturation programs. The mutant allele prevalent in semidwarf cultivars reduced the seed GA content by up to 2-fold at the early stage, which decelerated tissue morphogenesis including endosperm cell differentiation, delayed abscisic acid accumulation by a shift in the temporal distribution pattern, and postponed dehydration, physiological maturity, and germinability development. As the endosperm of developing seeds dominates the moisture equilibrium and desiccation status of the embryo in cereal crops, qSD1-2 is proposed to control primary dormancy by a GA-regulated dehydration mechanism. Allelic distribution of OsGA20ox2, the rice Green Revolution gene, was associated with the indica and japonica subspeciation. However, this research provided no evidence that the primitive indica- and common japonica-specific alleles at the presumably domestication-related locus functionally differentiate in plant height and seed dormancy. Thus, the evolutionary mechanism of this agriculturally important gene remains open for discussion.

Impact of sulfur (S) fertilization in paddy soils on copper (Cu) accumulation in rice (Oryza sativa L.) plants under flooding conditions

As the biogeochemical cycling of S in soil is closely associated with the mobility and bioavailability of heavy metals, in this study, we investigated the influence of S fertilization (S0 and SO4 2−) in paddy soils on rice growth, iron plaque formation over root surface, and Cu speciation of rice rhizosphere soil under flooding conditions. The dry weight and height of rice plants increased significantly after S fertilization, indicating that S fertilization of Cu-contaminated paddy soils can enhance rice growth. Sulfur fertilization (less than 500 mg/kg) promoted the formation of iron plaque, thus sequestering a large amount of Cu on root surface and decreasing the bioavailability of Cu by inducing transformation of Cu bioavailable fractions (exchangeable, carbonate oxides, or iron and manganese oxide bound to Cu) to Cu bound to organic matter. Copper K-edge X-ray absorption near-edge structure (XANES) revealed that S fertilization increased the percentage of Cu present as Cu2S and Cu–cysteine in rice rhizosphere soil, thus reducing Cu mobility. As Cu concentration in rice plants decreased and the biomass of rice plants increased after S fertilization, it can be suggested that S fertilization may be an effective approach for managing Cu-contaminated paddy soils.

Minimizing ammonia volatilization from urea, improving lowland rice (cv. MR219) seed germination, plant growth variables, nutrient uptake, and nutrient recovery using clinoptilolite zeolite

The anionic nature and high cation exchange capacity (CEC) of clinoptilolite zeolite can be exploited to reduce ammonia (NH3) loss from urea and to improve soil chemical properties to increase nutrient utilization efficiency in lowland rice cultivation. A closed-dynamic airflow system was used to determine NH3 loss from treatments (20, 40, and 60 g clinoptilolite zeolite pot−1). Seed germination study was conducted to evaluate the effects of clinoptilolite zeolite on rice seed germination. A pot study was conducted to determine the effects of clinoptilolite zeolite on rice plant growth variables, nutrient uptake, nutrient recovery, and soil chemical properties. Standard procedures were used to determine NH3 loss, rice plant height, number of leaves, number of tillers, dry matter production, nutrient uptake, nutrient recovery, and soil chemical properties. Application of clinoptilolite zeolite (15%) increased shoot elongation of seedlings and significantly reduced NH3 loss (up to 26% with 60 g zeolite pot−1), and increased number of leaves, total dry matter, nutrient uptake, nutrient recovery, soil pH, CEC, and exchangeable Na+. Amending acid soils with clinoptilolite zeolite can significantly minimize NH3 loss and improve rice plant growth variables, nutrient uptake, nutrient recovery, and soil chemical properties. These findings are being validated in our ongoing field trials.

Identification of QTLs for agronomic traits in indica rice using an RIL population

Increasing grain weight and breeding for ideal plant architecture are two means to improve the productivity of rice. Quantitative trait locus (QTL) mapping was conducted on ten yield component traits using a recombinant inbred line population derived from an indica × indica cross (M201 × JY293). Correlation analysis revealed that plant height, panicle length and flag leaf length, classified as plant morphology traits, were positively correlated with grain shape traits such as thousand-grain weight, grain length and grain width. Two tillering traits, total and effective tiller numbers, showed negative correlations with nearly all the other traits tested. A total of 37 QTLs were detected over the 2-year study period, and 14 of them were identified in both years. Four clustered QTLs corresponding to known genes/QTLs (GW2, GS3, qGL3 and qTGW3.3) were revealed on chromosomes 2 and 3, which had pleiotropic effects on grain weight and plant architecture traits. QTL mapping demonstrated that qGL3 was a major QTL controlling grain length and weight, as well as plant height, panicle length and flag leaf length in rice. Three new QTLs, qTGW3.0, qGL2.2 and qETN4, were detected in both years and worth attention in breeding for high-yield rice varieties.

Overexpression of a CYP94 family gene CYP94C2b increases internode length and plant height in rice

Plant growth is controlled by intrinsic developmental programmes and environmental cues. Jasmonate (JA) has important roles in both processes, by regulating cell division and differentiation, as well as in defense responses and senescence. We report an increase in rice plant height caused by overexpression of a gene encoding a cytochrome P450 enzyme, CYP94C2b, which promoted deactivation of JA-Ile. The height increase occurred through enhanced elongation of internodes in the absence of concomitant cell elongation, unlike previous findings with coi1 knock-down plants. Thus, modulating JA metabolism can increase the number of elongated cells in an internode. Based on these and previous findings, we discuss the difference in the effects of CYP94C2b overexpression vs. coi1 knock-down.

Rice Crop Monitoring and Yield Assessment with MODIS 250m Gridded Vegetation Products: A Case Study of Sa Kaeo Province, Thailand

Abstract. Billions of people in the world depend on rice as a staple food and as an income-generating crop. Asia is the leader in rice cultivation and it is necessary to maintain an up-to-date rice-related database to ensure food security as well as economic development. This study investigates general applicability of high temporal resolution Moderate Resolution Imaging Spectroradiometer (MODIS) 250m gridded vegetation product for monitoring rice crop growth, mapping rice crop acreage and analyzing crop yield, at the province-level. The MODIS 250m Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) time series data, field data and crop calendar information were utilized in this research in Sa Kaeo Province, Thailand. The following methodology was used: (1) data pre-processing and rice plant growth analysis using Vegetation Indices (VI) (2) extraction of rice acreage and start-of-season dates from VI time series data (3) accuracy assessment, and (4) yield analysis with MODIS VI. The results show a direct relationship between rice plant height and MODIS VI. The crop calendar information and the smoothed NDVI time series with Whittaker Smoother gave high rice acreage estimation (with 86% area accuracy and 75% classification accuracy). Point level yield analysis showed that the MODIS EVI is highly correlated with rice yield and yield prediction using maximum EVI in the rice cycle predicted yield with an average prediction error 4.2%. This study shows the immense potential of MODIS gridded vegetation product for keeping an up-to-date Geographic Information System of rice cultivation.

Agronomic Evaluation of Phosphorus Sources Applied to Upland and Lowland Rice

Rice is a staple food for more than 50 percent world’s population. It is mainly grown under two ecosystems, known as upland and lowland. Soils on which these two types of rice are grown are mostly deficient in phosphorus (P). Two field experiments were conducted (one with upland rice and another with lowland rice) with the objective to determine responses of upland and lowland rice to two sources of P fertilizers. The P sources were mono-ammonium phosphate and polymer coated mono-ammonium phosphate. The P rates used in the two experiments were 25, 50, 100, and 200 kg P2O5 ha−1 plus one control treatment. Plant height and grain yield of upland rice significantly increased with the addition of P fertilization. Similarly, plant height, straw yield, grain yield, panicle density, 1000-grain weight, P concentration, and uptake of lowland rice were significantly increased with the application of P fertilization. The response of these plant parameters to P fertilization was quadratic in nature. Rate of P for maximum growth, yield, and yield components varied for both upland and lowland rice. Maximum grain yield of upland rice was obtained with the addition of 108 kg phosphorus pentoxide (P2O5) ha−1 by mono-ammonium phosphate and 105 kg P2O5 ha−1 by polymer-coated mono-ammonium phosphate. Similarly, maximum grain yield of lowland rice was obtained with the addition of 143 kg P2O5 by mono-ammonium phosphate and 151 kg P2O5 by polymer-coated mono-ammonium phosphate. There were no significant differences between both the P sources for the growth, yield, and yield components of upland and lowland rice. Phosphorus-use efficiency defined in several ways decreased with increasing P rate in lowland rice.