Plant Type Rice Research Articles

Potential Yield of Glutinous Rice Varieties (Oryza sativa L. Var. glutinosa) Under Different Water Supply

Rice is a Gramineae plant. Each rice plant type has different morphology, physiological characteristics, and yields. Thus, genetic and environmental factors such as water availability influence those differences. West Nusa Tenggara (NTB) is one of Indonesia’s provinces with local glutinous rice strains cultivated by farmers. Local glutinous rice is grown on a field scale which depends on rainfall in this region. Therefore, plant growth rate and yield might decrease caused by inadequate amount of water during plant growth and development. Hence it is essential to find out the response of several strains of glutinous rice due to different water supplies, in addition to obtain adaptive glutinous rice strains under water deficit. This research was a factorial experiment with a randomized group design that contained two factors. The first factor was glutinous rice varieties, consisting of three local glutinous rice types: Me’e, Kala, Samada, and one National variety, Paketih. The second factor was the field capacity condition implemented by the amount of water supply: 2,250 ml (50 percent FC), 3,375 ml (75 percent FC), 4,500 ml (100 percent FC), and 5,625 ml (125 percent FC). Data were analyzed using a 5 percent analysis of variance, then proceeded with DMRT. The results showed that glutinous rice strains and water supply interacted with weight grains per clump. Meanwhile, there was no interaction on plant length, number of leaves, and weight of 100 grains. Samada variety showed adaptive behavior under limited water, presented on yield variable compared to the other varieties.

Stability analysis, agronomic performance, and grain quality of elite new plant type rice lines (Oryza sativa L.) developed for tropical lowland ecosystem

Rice is a major world staple food crop, and therefore breeding improved varieties is of ultimate importance. Genotype-by-environment analyses are essential to understand the potential performance of the lines over environments. This study aimed to elucidate the stability, agronomic performance, and grain quality of elite new plant type (NPT) rice lines developed for tropical lowland areas. Elite NPT rice lines were evaluated in eight locations along with national varieties as checks. Combined analysis across environments and several stability analyses were performed. The results revealed the possibility of breeding high-yielding NPT rice varieties with different stability profiles, namely broad adaptation (IPB189-F-13-1-1 (G5), bi = 0.91), suited for favorable environments (IPB187-F-37-1-2 (G1), bi = 1.47), and adapted to marginal environments (IPB193-F-30-2-1 (G9), bi = 0.54). G1 and G5 belonged to different groups of grain characteristics, each with low and high amylose content, respectively. The highest yielding line (IPB189-F-23-2-2 (G6), 8.68 ton ha−1) had an advantage of 19.39% over the highest yielding check, i.e., Inpari 32 (7.27 ton ha−1). This increase in yield was contributed by the success of breeding with a greater 1000-grain weight (11.91%) and number of filled grains per panicle (42.37%) than Inpari 32; meanwhile, the plant height also increased by 19 %. In addition, the rank correlations among three stability parameters, sdi2, Wi2, and σi2 were positive and highly significant. This study enlightens the prospect of breeding NPT rice varieties with different adaptations in tropical lowland areas.

IPA1 improves drought tolerance by activating SNAC1 in rice

Drought is a major abiotic stress to rice (Oryza sativa) during growth. Ideal Plant Architecture (IPA1), the first cloned gene controlling the ideal plant type in rice, has been reported to function in both ideal rice plant architecture and biotic resistance. Here, we report that the IPA1/OsSPL14, encoding a transcriptional factor, positively regulates drought tolerance in rice. The IPA1 is constitutively expressed and regulated by H2O2, abscisic acid, NaCl and polyethylene glycol 6000 treatments in rice. Furthermore, the IPA1-knockout plants showed much greater accumulation of H2O2 as measured by 3,3′-diaminobenzidine staining in leaves compared with WT plants. Yeast one-hybrid, dual-luciferase and electrophoretic mobility shift assays indicated that the IPA1 directly activates the promoter of SNAC1. Expression of SNAC1 is significantly down-regulated in IPA1 knockout plants. Further investigation indicated that the IPA1 plays a positive role in drought-stress tolerance by inducing reactive oxygen species scavenging in rice. Together, these findings indicated that the IPA1 played important roles in drought tolerance by regulating SNAC1, thus activating the antioxidant system in rice.

Disease Classification on Rice Leaves using DenseNet121, DenseNet169, DenseNet201

Rice is a plant that can grow in the tropics. This plant can produce food that can meet the needs of the people of a country. This plant can grow well if it is cared for properly. If the planting has used good care, such as providing adequate water, adding good fertilizer, it can be ascertained that it will produce a lot of rice fruit after harvesting. This often causes concern if rice growers have given good care but often produce less rice fruit because rice plants are attacked by various diseases. This is what makes the problem, that rice plants are attacked by diseases. Before spraying diseases or pests, farmers should have an understanding of diseases in rice. This makes farmers not wrong in choosing drugs for farmers' rice. It is very vulnerable if farmers do not know about the rice disease. Therefore, it is necessary to observe what types of rice diseases attack rice plants. Observations are not enough just to take pictures with a camera. But it is necessary to carry out further analysis of rice diseases. The presence of information technology is now able to recognize any type. One of the machine learning technologies is able to detect rice diseases. One of these branches of machine learning is deep learning. By using a dataset that focuses on rice disease, the model generated from deep learning training is able to detect rice disease. The purpose of this research is to predict disease in rice leaves using deep learning, namely DenseNet. Training using DenseNet, namely DenseNet121, DenseNet169 and DenseNet201. Accuracy using DenseNet121 reached 91.67%, DenseNet169 reached 90%, and DenseNet201 reached 88.33%. The model training time takes 24 seconds.

Effects and Mechanism of Enhanced UV-B Radiation on the Flag Leaf Angle of Rice.

Leaf angle is an influential agricultural trait that influences rice (Oryza sativa L.) plant type and yield, which results from the leaf bending from the vertical axis to the abaxial axis. UV-B radiation affects plant morphology, but the effects of varying UV-B intensities on rice flag leaves and the underlying molecular, cellular, and physiological mechanisms remain unknown. This experiment aims to examine the effect of natural light and field-enhanced UV-B radiation (2.5, 5.0, 7.5 kJ·m-2) on the leaf angle of the traditional rice variety Baijiaolaojing on Yuanyang terraces. In comparison with natural light, the content of brassinolide and gibberellin in rice flag leaves increased by 29.94% and 60.1%, respectively. The auxin content decreased by 17.3%. Compared with the natural light treatment, the cellulose content in the pulvini was reduced by 13.8% and hemicellulose content by 25.7% under 7.5 kJ·m-2 radiation intensity. The thick-walled cell area and vascular bundle area of the leaf pulvini decreased with increasing radiation intensity, and the growth of mechanical tissue in the rice leaf pulvini was inhibited. The flag leaf angle of rice was greatest at 7.5 kJ·m-2 radiation intensity, with an increase of 50.2%. There are two pathways by which the angle of rice flag leaves is controlled under high-intensity UV-B radiation. The leaf angle regulation genes OsBUL1, OsGSR1, and OsARF19 control hormone levels, whereas the ILA1 gene controls fiber levels. Therefore, as cellulose, hemicellulose, sclerenchyma, and vascular bundles weaken the mechanical support of the pulvini, the angle of the flag leaf increases.

The shifting genetic diversity pattern of Indonesian rice improved varieties from 1943-2019 based on historical pedigree data

Abstract. Anas, Damayanti F, Kadapi M, Carsono N, Sari S. 2022. The shifting genetic diversity pattern of Indonesian rice improved varieties from 1943-2019 based on historical pedigree data. Biodiversitas 23: 4649-4656. For rice plants in Indonesia, stagnation in increasing crop yields due to a reduction in genetic diversity is a significant issue. The issue of using the same parents in breeding programs and consumer preferences for a single main variety are among the causes of the narrowing of rice plants' genetic diversity. The purpose of this study is to figure out which ancestors are significant and how the genetic diversity of improved Indonesian rice cultivars has changed over time. Changes in the genetic background of the Indonesian rice gene pool were decided using pedigree analysis by calculating the coefficient of parentage (COP) among varieties. There are 280 ancestors in the rice gene pool. The pedigree map exemplifies the complexities of rice breeding in Indonesia. The four classical ancestors of DGWG, Taichung Native1, China, and Latisail had a noteworthy influence on all irrigated rice plant types (11.22%) and upland rice plant types (8.30%) in the gene pool. The dominance of the phenomenal variety IR64 has been continued by Inpari 32, which is a direct derivative of Ciherang. In the meantime, Inpago9, Luhur 2, and UPLRI ancestors set the foundation for the upland rice plant type. Inpara7 and Inpara9, along with their IRRI-introduced parents (IRRIpara4 and IRRIpara5), had a significant impact on Indonesian tidal rice plants. The A1, Hipa7, and Hipa3 varieties are heavily influenced by the hybrid rice plants of Indonesia.

Effects of Nitrogen and Phosphorus Regulation on Plant Type, Population Ecology and Sheath Blight of Hybrid Rice.

(1) Background: Sheath blight is one of the most economically significant rice diseases worldwide. A study was conducted in order to find the relationship and impact of the amount of nitrogen (N) and phosphorus (P) application on the hybrid rice population microclimate and the severity of sheath blight. (2) Methods: Four N and four P application levels were used to determine their impact on plant type, temperature, and humidity variation in different positions of population and the severity of sheath blight in the later stage. (3) Results: We found that N and P application levels could affect the plant type and change the population temperature and humidity by increasing the leaf length and leaf angle. (4) Conclusions: N application had a more significant (p < 0.05) impact on the plant type. High N application caused decreased temperature (hybrid rice population), while increased humidity (especially the population base layer at grain filling stage) resulted in severe sheath blight. High P application had similar impacts; however, P application increased material and nitrogen transport in plants and reduced the severity of sheath blight.

Leaf microstructure and photosynthetic characteristicsof a rice midvein-deficient mutant dl-14

Midvein is an important structure of the upright leaf of rice, and its normal development is essential to the formation of a common plant type of rice (Oryza sativa L.). To reveal the effect of midvein deficiency on photosynthesis-related characteristics, leaf microstructure, and vein characteristics, the photosynthetic features between the midvein-deficient mutant dl-14 and wild-type Huanghuazhan plants were analyzed. The results indicated that the midvein area of the dl-4 mutant lacked large intercellular space and instead it was filled with mesophyll cells. Moreover, the vein density of the dl-14 mutant was significantly higher than that in cv. Huanghuazhan. Chlorophyll (Chl) a, Chl b, and carotenoid content were markedly elevated in dl-14. In terms of photosynthetic characteristics, we observed that under high irradiance and high CO2 concentration, the net photosynthetic rate of dl-14 plants was significantly higher than that of Huanghuazhan plants, but its water use efficiency was significantly lower. In addition, several major photosynthetic parameters, including characteristics of chlorophyll fluorescence (the efficiency of excitation capture of open PS II center, photochemical quenching, effective quantum yield of PS II photochemistry, and electron transfer rate) were significantly higher in dl-14 plants compared to Huanghuazhan plants, but the nonphotochemical quenching of dl-14 mutant was significantly lower than that of Huanghuazhan. These findings indicate that the dl-14 mutant has higher vein density, stronger photon conversion ability, and weaker radiation dissipation ability. This study can provide theoretical support for breeders to use the midvein-deficient mutant.

Characterization of QTLs for grain weight from New Plant Type rice cultivars through the development of near-isogenic lines with an IR 64 background

Characterization of QTLs for grain weight from New Plant Type rice cultivars through the development of near-isogenic lines with an IR 64 background

The Study of Superior Varieties and New Plant Types of Rice on Various Organic Cropping Systems in Tidal Land

&lt;div&gt;&lt;p&gt;&lt;strong&gt; &lt;/strong&gt;&lt;/p&gt;&lt;/div&gt;&lt;div&gt;&lt;p&gt;Increasing rice production with the use of high-yielding varieties and proper plant spacing must consider the environmental aspect. Organic agriculture is an effort to accelerate the cultivation techniques with environmental health, in addition, the research site is a tidal land that has been cultivating rice organically since 2009. The research aimed to study the growth and yield of superior varieties and new plant type of rice on various cropping systems in tidal land. The research was carried out at the Laboratory of Center for Protection of Food Crops and Horticulture, Sungai Tabuk District, Banjar Regency. The experimental design was a split-plot with three replications. The main plot were s1 = Tile System, s2 = Legowo System 2:1, s3 = Legowo System 8:1 cropping systems and subplots were v1= Ciherang, v2= Mekongga, v3= IPB Batola 6R, v4= IPB 3S varieties. The experimental unit was a plot with a size of 10 m&lt;sup&gt;2&lt;/sup&gt;. The results showed that there was no interaction between cropping systems and rice varieties. The main plot of cropping system Legowo 2:1 showed the best percentage of filled grain per panicle (87%). Sub-plot of rice varieties affected some plant growth and yield variables. Superior varieties &lt;em&gt;Ciherang&lt;/em&gt; and &lt;em&gt;Mekongga&lt;/em&gt; had more tillers and panicles per clump. The new plant type varieties showed a greater number of grains per panicle and tended to have a better percentage of filled grains per panicle and a weight of 1,000 grains.&lt;/p&gt;&lt;/div&gt;

Genotype by Environment Interaction of IPB New Plant Type Rice Lines in Three Irrigated Lowland Locations

One essential objective of rice breeding is to obtain high-yielding varieties. This study aims to (1) determine the effect of genotype (G), environment (E), and genotype by environment (G×E) interaction on agronomic traits and yield of 12 lowland rice genotypes, (2) estimate variance components and repeatability (3) identify promising rice genotypes with good agronomic performance and high yield potential. The trials were conducted in three irrigated lowland locations from June to November 2020, using a randomized complete block design with three replications. The results showed that the G×E interaction effect was significant on days to flowering, days to harvest, plant height, number of tillers, and panicle length. The genotype's main effect was significant on yield. Four IPB lines (IPB189-F-13-1-1, IPB189-F-23-2-2, IPB193-F-17-2-3, and IPB193-F-30-2-1) had a higher average yield than Ciherang and Inpari 32 varieties. The IPB189-F-23-2-2 had a panicle length stability across the three test locations and a higher average yield than the checks.

A trait-based model ensemble approach to design rice plant types for future climate.

Crop models are powerful tools to support breeding because of their capability to explore genotype×environment×management interactions that can help design promising plant types under climate change. However, relationships between plant traits and model parameters are often model specific and not necessarily direct, depending on how models formulate plant morphological and physiological features. This hinders model application in plant breeding. We developed a novel trait-based multi-model ensemble approach to improve the design of rice plant types for future climate projections. We conducted multi-model simulations targeting enhanced productivity, and aggregated results into model-ensemble sets of phenotypic traits as defined by breeders rather than by model parameters. This allowed to overcome the limitations due to ambiguities in trait-parameter mapping from single modelling approaches. Breeders' knowledge and perspective were integrated to provide clear mapping from designed plant types to breeding traits. Nine crop models from the AgMIP-Rice Project and sensitivity analysis techniques were used to explore trait responses under different climate and management scenarios at four sites. The method demonstrated the potential of yield improvement that ranged from 15.8% to 41.5% compared to the current cultivars under mid-century climate projections. These results highlight the primary role of phenological traits to improve crop adaptation to climate change, as well as traits involved with canopy development and structure. The variability of plant types derived with different models supported model ensembles to handle related uncertainty. Nevertheless, the models agreed in capturing the effect of the heterogeneity in climate conditions across sites on key traits, highlighting the need for context-specific breeding programmes to improve crop adaptation to climate change. Although further improvement is needed for crop models to fully support breeding programmes, a trait-based ensemble approach represents a major step towards the integration of crop modelling and breeding to address climate change challenges and develop adaptation options.

ADVANCED GENETIC STRATEGIES FOR IMPROVING RICE YIELD

Every crop breeding effort aims to increase production. Despite several advances, most worldwide breeding projects have traditionally focused on improving grain production potential, insect/pest and disease resistance, grain quality, and stress tolerance. Almost all rice breeding initiatives aim to increase grain yield. However, the value of this crop varies by area, country, and even within a country. Finding innovative ways to increase the genetic grain production potential of all kinds has significant ramifications. Rice breeders have improved crop yields significantly. The green revolution gave us semi-dwarf rice types, a new rice plant type, and hybrid rice. Conventional hybridization, ideotype and heterosis breeding, broad hybridization, genetic engineering, molecular marker-assisted breeding, and CRISPR-Cas9 are all possibilities for increasing yield potential. Pedigree is the most common breeding technique for enhancing rice, but hybrids and population improvement are also used. Many groups are still working to integrate biotechnology tools into breeding programs and balance budget allocation between conventional and innovative approaches. Modern technology, such as biotechnology, has recently increased agricultural productivity by improving crop yields and reviewing several genome editing methods to enhance rice production. Keywords: Rice (Oryza sativa L.), genetic engineering, ideotype breeding, RISPR-Cas9.

Quantitative Evaluation of Leaf Morphology with Different Rice Genotypes Based on Image Processing

Prostrate growth 1 (PROG1) gene is vital in controlling the prostrate growth habit of rice. Studying the effect of PROG1 gene on rice canopy structure is crucial in elucidating the molecular mechanism of rice plant type evolution. Herein, the morphological characteristics of different rice genotypes were collected at different growth stages and leaf nodes using image processing techniques. The morphological characteristics included leaf length, leaf width, and leaf area. The image processing techniques involved boundary mean oscillation (BMO) filtering and minimum bounding rectangle extraction of the target image. On this basis, the effect of the PROG1 gene on rice leaf morphology was quantitatively assessed. Also, the feasibility of image processing techniques in detecting the morphological characteristics of rice leaves was discussed. Under the influence of the PROG1 gene, the length, width, and area of rice leaves decreased by 45.1%, 12.7%, and 44.8%, respectively, at the booting stage. Similarly, the length, width, and area of flag leaves decreased by 15.8%, 32.0%, and 33.7% at the heading stage and by 25.4%, 16.2%, and 19.7% at the filling stage, respectively, and that of secondary leaf reduced by 23.2%, 13.6%, and 54.2% at heading stage and by 24.1%, 17.3%, and 37.0% at filling stage, respectively. Furthermore, the length, width, and area of other leaves reduced by 32.3%, 9.8%, and 51.6% at the heading stage and by 28.6%, 7.3%, and 36.7% at the filling stage, respectively. The leaves in the rice canopy were shorter, narrower, and smaller in leaf area. Notably, no significant differences were found between image processing technology and manual measurement methods regarding the values of leaf morphological characteristics obtained ( P &lt; 0.05 ). Thus, these results show that image processing technology is effective in studying the morphological characteristics of rice leaves. This study provides a reliable foundation for molecular breeding studies and will guide the application of the PROG1 gene in molecular breeding.

QTL mapping and analysis of candidate genes in flag leaf morphology in rice

<p indent=0mm>Leaf is an important organ of rice, and it is the main place for photosynthesis. Leaf morphology related traits such as leaf length, leaf width and leaf area can directly affect leaf photosynthetic efficiency. The study of quantitative trait loci (QTL) sites for morphological characters of rice flag leaf and the improvement of morphological characters of rice flag leaf by means of genetic breeding can provide theoretical basis for the cultivation of ideal plant type rice. In this study, an indica rice variety HZ was used as the male parent, and a japonica rice variety Nekken2 was used as the female parent. After F1 generation was obtained by cross-breeding, 120 recombinant inbred lines (RIL populations) were obtained from successive generations of self-crossing, which were used as experimental materials in this study. Leaf length, leaf width, leaf area of rice at tillering stage and mature stage were studied and analyzed after incubation under the same and appropriate conditions. At the same time, the genetic map was constructed by using the RIL population to locate the QTLs for the traits of leaf length, leaf width and leaf area in rice at tillering stage and mature stage, 35 QTLs related to leaf morphology were detected. There were 6 QTLs related to blade length (5 at tillering stage, 1 at maturation stage), LOD value of one of them was as high as 6.92; 8 QTLs related to blade width (detected only at tillering stage), LOD value of one was as high as 4.51; 21 QTLs related to blade area (12 at tillering stage, 9 at mature stage), LOD values of two of them were as high as 6.37 and 4.06 respectively. Through quantitative analysis of the candidate genes related to leaf length, leaf width and leaf area in these QTL regions, it was found that<italic> LOC_Os02g52040</italic>, <italic>LOC_Os03g46610</italic>,<italic> LOC_Os04g52230</italic>,<italic> LOC_Os04g42230</italic>,<italic> LOC_Os04g44150</italic>,<italic> LOC_Os04g52479</italic>,<italic> LOC_Os09g37400 </italic>and <italic>LOC_Os12g42020</italic> were significantly different in expression levels between the parents. Combined with the data of leaf length, leaf width and leaf area of the parents, we speculated that The high expressions of<italic> LOC_Os04g52230</italic>, <italic>LOC_Os04g44150</italic>,<italic> LOC_Os09g37400 </italic>and <italic>LOC_Os12g42020</italic> may promote the growth of leaf width and leaf area, while the high expressions of <italic>LOC_Os02g52040</italic>, <italic>LOC_Os03g46610 </italic>and <italic>LOC_Os04g52479 </italic>may inhibit the growth of rice flag leaves. Through the analysis of QTL in this study, QTL regulating leaf length, leaf width and leaf area of rice flag leaf were excavated, which provided a reference for cultivating new rice varieties with excellent plant type.

Major QTLs, qARO1 and qARO9, Additively Regulate Adaxial Leaf Rolling in Rice.

Moderate leaf rolling is considered optimal for the ideal plant type in rice (Oryza sativa L.), as it improves photosynthetic efficiency and, consequently, grain yield. Determining the genetic basis of leaf rolling via the identification of quantitative trait loci (QTLs) could facilitate the development of high-yielding varieties. In this study, we identified three stable rice QTLs, qARO1, qARO5, and qARO9, which control adaxial leaf rolling in a recombinant inbred line (RIL) population derived from a cross between Tong 88-7 (T887) and Milyang 23 (M23), using high-density SNP markers. These QTLs controlled the rolling phenotype of both the flag leaf (FL) and secondary leaf (SL), and different allelic combinations of these QTLs led to a wide variation in the degree of leaf rolling. Additive gene actions of qARO1 and qARO9 on leaf rolling were observed in a backcross population. In addition, qARO1 (markers: 01id4854718 and 01asp4916781) and qARO9 (markers: 09id19650402 and 09id19740436) were successfully fine-mapped to approximately 60- and 90-kb intervals on chromosomes 1 and 9, respectively. Histological analysis of near-isogenic lines (NILs) revealed that qARO1 influences leaf thickness across the small vein, and qARO9 affects leaf thickness in the entire leaf and bulliform cell area, thus leading to adaxial leaf rolling. The results of this study advance our understanding of the genetic and molecular bases of adaxial leaf rolling, and this information can be used for the development of rice varieties with the ideal plant type.

Classification of diseases for rice plant based on Naive Bayes classifier with a combination of PROMETHEE

Rice is a staple food crop for most of the population in Indonesia. The need for food, such as rice, is increasing every year. However, in recent years, the low productivity is due to the prolonged dry season. Also, quality rice production can be influenced by several factors, such as the presence of pests and diseases that attack rice plants so that farmers have difficulty dealing with them. Most of the researchers have applied a measure with an intelligence-based measurement; however, the obtained accuracy cannot achieve maximum. Therefore, in this research, a new approach was carried out using the Naive Bayes and PROMETHEE method to determine diseases and pests in rice that have been proposed to reduce the risk of errors and shorten the time in decision making. The contribution of this research is to identifying these problems, including the search for prior probability, conditional probability, posterior probability, and ranking that can use the Naive Bayes and PROMETHEE method to result the highest accuration value. So, this research can be use rapid decision making based on learning data. From the sample's data of the Agriculture Office of Lamongan Regency, East Java pointed out that 38 symptoms can cause 13 types of diseases and rice plants' pests based on the learning process has 73.91% accuracy with k=3. Testing the system used data on pest and disease disturbances as many as 180 data and the data division using k is 4. It proves that the naive bayes and PROMETHEE method is able to give better results.

Compact plant type rice has higher lodging and N resistance under machine transplanting

To identify the major factors that contribute to the difference in lodging among different rice varieties under machine transplanting and their responses to nitrogen (N), field experiments were conducted at Danyang County (a representative eco-site of the Lower Yangtze River) in Jiangsu Province, China in 2017 and 2018, 22 hybrid indica varieties (HIs), 22 inbred japonica varieties (IJs) and two indica japonica hybrid varieties (IJHs) were transplanted by machine with three N rates (N0, N150 and N300, 0, 150 and 300 kg ha–1, respectively). Lodging-related physical parameters, morphological characteristics and apparent transport rates of dry matter were examined. Significant difference in yield was observed among different types of rice, and followed by IJs<HIs<IJHs. The average lodging index (LI) of hybrid varieties (HIs and IJHs) was higher than that of the inbred varieties (IJs) with higher plant height; moreover, lower apparent export rate of dry matter resulted lower LI in IJHs than in HIs. The HIs had a large difference in the LI, which came from the difference in bending stress (BS) induced by the difference in the apparent export rate of dry matter, varieties with lower leaf angle of upper three leaves possess strong lodging resistance capacity; however, the gap among the IJs was due to the difference in the cross section modulus (Z). The LI in the IJs or IJHs increased slightly with the increased N application, and there was no lodging incidence under the high N level, which was due to the low leaf angle and barely changed under high N; there was a significant interaction between varieties (HIs) and N rates in lodging rate and LI, varieties with lower leaf angle of upper three leaves were resistant to high N. These results suggest that compact plant type rice has higher lodging and N resistance at machine-transplanting method.

Construction of a High-Density Genetic Map Based on SLAF Markers and QTL Analysis of Leaf Size in Rice.

Leaf shape is an important agronomic trait for constructing an ideal plant type in rice, and high-density genetic map is facilitative in improving accuracy and efficiency for quantitative trait loci (QTL) analysis of leaf trait. In this study, a high-density genetic map contained 10,760 specific length amplified fragment sequencing (SLAF) markers was established based on 149 recombinant inbred lines (RILs) derived from the cross between Rekuangeng (RKG) and Taizhong1 (TN1), which exhibited 1,613.59 cM map distance with an average interval of 0.17 cM. A total of 24 QTLs were detected and explained the phenotypic variance ranged from 9% to 33.8% related to the leaf morphology across two areas. Among them, one uncloned major QTL qTLLW1 (qTLL1 and qTLLW1) involved in regulating leaf length and leaf width with max 33.8% and 22.5% phenotypic variance respectively was located on chromosome 1, and another major locus qTLW4 affecting leaf width accounted for max 25.3% phenotypic variance was mapped on chromosome 4. Fine mapping and qRT-PCR expression analysis indicated that qTLW4 may be allelic to NAL1 (Narrow leaf 1) gene.

Dinamika Amonium dan Nitrat Lahan Sawah Latosol pada Budidaya Konvensional Padi Lokal dan Hibrida di Subak Jatiluwih

Ammonium Dynamics and Latosol Wetland Nitrates in Conventional Cultivation of Local and Hybrid Rice in Jatiluwih Subak. Plants absorb nitrogen in the form of ammonium (NH4+) and nitrate (NO3-). Each sample was analyzed for its ammonium and nitrate levels using macro Kjeldahl method. The results showed that the concentration of ammonium and nitrate in soil of the two rice fields were similar. The ions contents were as following: nitrate (2,67%) and ammonium (2,67%) in local rice, while those in hybrid rice fields were amounted of 1,48% and 4,59% respectivelly. The concentration of ammonium and nitrate on 21 DAC in soil samples remained low and rose at 28 DAC, then decreased at 56 DAC. It means that the times of fertilizing always done by the farmers were not appropriate.The content of ammonium and nitrate in water phase much lower than that in soils for both types of rice plants. The highest concentration of ammonium in local rice fields was 0,093% at the time of tillage and the lowest 0% on 21 DAC, while the highest nitrate concentrations in local rice water was 0,37% at 70 DAC and the lowest was 0% at of 21 DAC. The highest ammonium concentrations in hybrid rice 0,33% at 14 DAC, and the lowest 0% at 42 HST, while the highest nitrate content 0,47% at 42 DAC and the lowest 0% at the time of tillage. The fertilizing times recommended based on the findings of this reaserch is at 10-15 DAC for both rice types and another subsquent fertilization on 60-65 DAC for local rice and 40-45 DAC in hybrid rice.