Indica Type Research Articles

Generic Workflow of a Highly Effective and Easy Anther Culture Method for Both Japonica and Indica Rice.

As one of the most important staple crops in the world, rice plays a pivotal role in world food security. The creation of doubled haploids based on anther culture is an important technology for rice breeding. However, at present, rice anther culture technology still faces many problems, such as genotype dependency, especially genotypes of indica rice. In this study, fifteen rice genotypes, including twelve japonica rice genotypes and three indica rice genotypes, were randomly selected and used to study anther culture by using a modified M8 medium. The results showed that the total callus induction rates of these different rice genotypes ranged from 0.81 to 13.95%, with an average of 6.64%, while the callus induction rates calculated for the top ten highest callus inductions for each rice genotype ranged from 2.75 to 17.00%, with an average of 10.56%. There were varying gaps between the total callus induction rates and the callus induction rates in these different rice genotypes. The fact that the gaps for some rice genotypes were relatively large indicated that standard tiller or anther collection was not applicable to all rice genotypes and that there was still a lot of room for improvement in the callus induction rate of some rice genotypes through optimization of the sampling method. The plantlet regeneration rates ranged from 12.55 to 456.54%, with an average of 200.10%. Although there were many albinos from anther culture for some rice genotypes, these would still meet the requirement if the rice genotypes had higher callus induction rates or regeneration rates. The percentages of seed setting of regenerated green seedlings ranged from 14% to 84%, with an average of 48.73%. Genetic diversity analysis showed that the genetic background of these different rice genotypes was representative, and the phylogenetic tree and Principal Component Analysis (PCA) divided them into indica and japonica types. Therefore, in this study, an anther culture method suitable for both indica and japonica rice genotypes was established, which could improve doubled haploid breeding in rice.

Classification of Cannabis Strains Based on their Chemical Fingerprint-A Broad Analysis of Chemovars in the German Market.

Introduction: Cannabis cultivars were usually categorized based on their genetic profile as sativa, indica, or hybrid types. However, these three criteria do not allow sufficient differentiation between the numerous varieties of cannabis strains. Furthermore, this classification is based on morphological and bio-geographical properties of the plants and does not represent the chemical composition of different cultivars. The concentration of cannabinoids and terpenes are crucial for the pharmacological effect, not only because of the known entourage effect, and therefore needs to be considered by categorization. Materials and Methods: A total of 140 medicinal cannabis flowers available on the German market were analyzed regarding their individual terpene profile using GC-MS analysis. Statistical evaluation was performed to investigate correlations and data relations as well as for clustering. Results: Multivariate analysis showed correlations between individual terpenes. However, there was no statistical correlation between terpene profiles and their respective genetic profile. Terpene profiles of sativa, indica, and hybrid strains are quite heterogenous and clearly showed that there is no relation between terpenes and the estimated pharmacological effect. As a result, we suggest a new classification system based on individual terpene profiles to faster a comprehensive understanding of the expected medical effect. Discussion: Considering main terpenes, we established a concept of six clusters with various terpene profiles being attributed to different medicinal applications. We excluded tetrahydrocannabinol (THC) and cannabidiol (CBD) content from clustering as most of the strains were THC dominant and therefore distort the results. Our pattern of strains with similar terpene profiles might refine the existing classes of chemotypes with different THC:CBD content. Conclusion: The categorization of cannabis strains based on their terpene profiles allows a clearer, finer and, above all, more meaningful classification than the existing sativa/indica classification. Due to the entourage effect and the interactions between cannabinoids and terpenes, this group of substances is also given the necessary consideration when selecting the right medicine for the individual. Within the next steps, further studies are needed with the aim of mapping clinical validated effects to our chemovars. If it is possible to correlate therapy of symptoms to specific chemical profiles personalized cannabinoid therapy will be possible.

Genome‐wide study of OsWRKY gene in Oryza sativa subsp. japonica

AbstractWRKY transcription factor (TF) family is well known to govern essential physiological functioning as well as regulate plant response to biotic and abiotic stress. In this study, we have identified 108 OsWRKY genes in the genome of Oryza sativa subsp. japonica, using the updated genomic data from the Rice Annotation Project Database and Oryzabase, which were further used to conduct the phylogenetic study, motif analysis, gene structure analysis, chromosomal mapping, and prediction of sub‐cellular localization. The multiple sequence alignment OsWRKY proteins revealed the presence of nine different types of alterations in the conserved heptapeptide sequence WRKYGQK associated with 19 OsWRKY genes. Physiochemical analysis discloses the hydrophobic amino acid‐rich, thermally stable, and polar nature of OsWRKY proteins. These genes were noted as highly conserved between the two cultivated sub‐species of Oryza sativa, that is Indica and japonica type. Additionally, from motif analysis, we have found a new motif, which was categorized as hAT family C‐terminal dimerization region associated with four members of group IIc. We have identified 21 stress‐responsive OsWRKY genes, and their significance to the different biotic and abiotic stress‐mediated cascades was further evaluated by analysing 1500 kb upstream sequences and this disclosed the presence of important phytohormone‐responsive cis‐elements in the OsWRKY gene, suggesting its direct involvement in defence against a wide range of external stressors and these 21 OsWRKY genes are tentatively listed as possible candidates for more study.

Characterization of rice (Oryza sativa L.) landraces from Majuli and surrounding riverine ecologies in Assam: Assessment of morphogenetic variability and submergence tolerance

AbstractRice landraces from the fragile riverine ecosystems surrounding Majuli islands in Assam are pivotal for local livelihoods, as well as for their potential in developing flood tolerant varieties. We characterized 87 landraces from Majuli, Dhemaji, and North Lakhimpur districts in Assam by assessing 36 agro‐morphological traits, submergence tolerance, and microsatellite diversity. Multivariate analyses revealed that grain and leaf characteristics, plant height, and tillering are important traits differentiating the cultivar types. Sixty‐six SSR markers generated 271 alleles with an average of 4.1 alleles per marker with population structuring in two clusters having an allele frequency divergence of 0.124. The Bao or deep‐water landraces displayed the highest phenotypic and genetic diversity, with potential genetic links to the aus and wild species. Sali (winter rice) and bora (sticky rice) landraces were predominantly indica type. Nearly 47% of the germplasm exhibited tolerance to two‐week submergence at seedling stage. Surveying SUB1A and SNORKEL genes revealed the presence of SUB1A‐1 and SNORKEL genes in 64% and 57% of the tolerant accessions, respectively. This study highlights the untapped potential of rice landraces in a fragile ecological region, providing insights into their agronomical traits, submergence tolerance, and genetic diversity. The findings lay the foundation for improved germplasm management and developing flood‐resilient rice varieties, crucial for sustainable agriculture in riverine ecosystems.

Metabolic diversity analysis and genome wide assessment of oxalate accumulation in the leaves of rice (Oryza sativa) cultivars.

Soluble oxalate accumulates in rice leaves, and it causes mineral deficiency and urinary syndrome in livestock that consume the leaves. In our previous study, we found that the oxalate content was higher in the leaves of Koshihikari (japonica type cultivar) than in those of Takanari (indica type cultivar). This difference was seen even when the two cultivars were grown under a high CO2 concentration, which inhibits oxalate synthesis via photorespiration, suggesting that the difference resulted from genetic factors rather than environmental factors. To clarify whether genetic factors affect the oxalate content of rice leaves, we measured the contents of oxalate and oxalate-related organic acids in the leaves of various rice cultivars the Rice Core Collection (WRC) and Japan Rice Core Collection (JRC) by capillary electrophoresis-mass spectrometry. Results showed that japonica type cultivars tended to accumulate more oxalate than aus or indica type cultivars. Correlation analysis revealed a positive correlation between oxalate accumulation and the citrate content, suggesting that the isocitrate pathway is involved in oxalate accumulation. On the other hand, a genome-wide association study for the oxalate content of the WRC and JRC cultivars did not reveal significant loci directly related to oxalate accumulation. This indicates that the combination of various loci may affect the oxalate contents of rice leaves.

Population Structure and Genetic Diversity of Shanlan Landrace Rice for GWAS of Cooking and Eating Quality Traits.

The Shanlan landrace rice in Hainan Province, China, is a unique upland rice germplasm that holds significant value as a genetic resource for rice breeding. However, its genetic diversity and its usefulness in rice breeding have not been fully explored. In this study, a total of eighty-four Shanlan rice, three typical japonica rice cultivars, and three typical indica rice cultivars were subjected to resequencing of their genomes. As a result, 11.2 million high-quality single nucleotide polymorphisms (SNPs) and 1.6 million insertion/deletions (InDels) were detected. Population structure analysis showed all the rice accessions could be divided into three main groups, i.e., Geng/japonica 1 (GJ1), GJ2, and Xian/indica (XI). However, the GJ1 group only had seven accessions including three typical japonica cultivars, indicating that most Shanlan landrace rice are different from the modern japonica rice. Principal component analysis (PCA) showed that the first three principal components explained 60.7% of the genetic variation. Wide genetic diversity in starch physicochemical parameters, such as apparent amylose content (AAC), pasting viscosity, texture properties, thermal properties, and retrogradation representing the cooking and eating quality was also revealed among all accessions. The genome-wide association study (GWAS) for these traits was conducted and identified 32 marker trait associations in the entire population. Notably, the well-known gene Waxy (Wx) was identified for AAC, breakdown viscosity, and gumminess of the gel texture, and SSIIa was identified for percentage of retrogradation and peak gelatinization temperature. Upon further analysis of nucleotide diversity in Wx, six different alleles, wx, Wxa, Wxb, Wxin, Wxla/mw, and Wxlv in Shanlan landrace rice were identified, indicating rich gene resources in Shanlan rice for quality rice breeding. These findings are expected to contribute to the development of new rice with premium quality.

Exploring Genetics by Environment Interactions in Some Rice Genotypes across Varied Environmental Conditions.

Rice production faces challenges related to diverse climate change processes. Heat stress combined with low humidity, water scarcity, and salinity are the foremost threats in its cultivation. The present investigation aimed at identifying the most resilient rice genotypes with yield stability to cope with the current waves of climate change. A total of 34 rice genotypes were exposed to multilocation trials. These locations had different environmental conditions, mainly normal, heat stress with low humidity, and salinity-affected soils. The genotypes were assessed for their yield stability under these conditions. The newly developed metan package of R-studio was employed to perform additive main effects and multiplicative interactions modelling and genotype-by-environment modelling. The results indicated that there were highly significant differences among the tested genotypes and environments. The main effects of the environments accounted for the largest portion of the total yield sum of squared deviations, while different sets of genotypes showed good performance in different environments. AMMI1 and GGE biplots confirmed that Giza179 was the highest-yielding genotype, whereas Giza178 was considered the most-adopted and highest-yielding genotype across environments. These findings were further confirmed by the which-won-where analysis, which explained that Giza178 has the greatest adaptability to the different climatic conditions under study. While Giza179 was the best under normal environments, N22 recorded the uppermost values under heat stress coupled with low humidity, and GZ1968-S-5-4 manifested superior performance regarding salinity-affected soils. Giza 177 was implicated regarding harsh environments. The mean vs. stability-based rankings indicated that the highest-ranked genotypes were Giza179 > Giza178 > IET1444 > IR65600-77 > GZ1968-S-5-4 > N22 > IR11L236 > IR12G3213. Among them, Giza178, IR65600-77, and IR12G3213 were the most stable genotypes. Furthermore, these results were confirmed by cluster-analysis-based stability indices. A significant and positive correlation was detected between the overall yield under all the environments with panicle length, number of panicles per plant, and thousand grain weight. Our study sheds light on the notion that the Indica/Japonica and Indica types have greater stability potential over the Japonica ones, as well as the potential utilization of genotypes with wide adaptability, stability, and high yield, such as Giza178, in the breeding programs for climate change resilience in rice.

Haploid Induction in Indica Rice: Exploring New Opportunities.

Haploid plants are of significant interest to crop breeders due to their ability to expedite the development of inbred lines. Chromosome-doubling of haploids, produced by either in vitro or in vivo methods, results in fully homozygous doubled haploids. For nearly five decades, in vitro methods of anther and microspore culture have been attempted in many crops. In rice, in vitro methods are used with some success in japonica cultivars, although indica types have remained recalcitrant to a large extent. This review aims to explore the reasons for the lack of success of in vitro methods in indica rice and discuss new advancements in in vivo haploid induction protocols in other cereals and their relevance to rice. In particular, the current level of understanding of in vivo haploid inducer systems that utilize MTL and CENH3 mutants is analyzed in detail. One notable advantage of in vivo haploid induction systems is that they do not require tissue culture competence. This makes these methods more accessible and potentially transformative for research, offering a pragmatic approach to improving indica rice cultivars. By embracing these in vivo methods and harnessing the power of gene editing technologies like CRISPR/Cas9 systems, breeders can reshape their approach to indica rice improvement.

Crop-Weed Introgression Plays Critical Roles in Genetic Differentiation and Diversity of Weedy Rice: A Case Study of Human-Influenced Weed Evolution.

As an important driving force, introgression plays an essential role in shaping the evolution of plant species. However, knowledge concerning how introgression affects plant evolution in agroecosystems with strong human influences is still limited. To generate such knowledge, we used InDel (insertion/deletion) molecular fingerprints to determine the level of introgression from japonica rice cultivars into the indica type of weedy rice. We also analyzed the impact of crop-to-weed introgression on the genetic differentiation and diversity of weedy rice, using InDel (insertion/deletion) and SSR (simple sequence repeat) molecular fingerprints. Results based on the STRUCTURE analysis indicated an evident admixture of some weedy rice samples with indica and japonica components, suggesting different levels of introgression from japonica rice cultivars to the indica type of weedy rice. The principal coordinate analyses indicated indica-japonica genetic differentiation among weedy rice samples, which was positively correlated with the introgression of japonica-specific alleles from the rice cultivars. In addition, increased crop-to-weed introgression formed a parabola pattern of dynamic genetic diversity in weedy rice. Our findings based on this case study provide evidence that human activities, such as the frequent change in crop varieties, can strongly influence weed evolution by altering genetic differentiation and genetic diversity through crop-weed introgression in agroecosystems.

Insights into the recent approaches for rice (Oryza sativa L.) biofortification

Rice is the most essential source of calories for humans among the cereals and over half of the world's population is fed on rice. As part of a complete food systems approach, biofortification is an effective technique for nutrition enrichment which refers to the development of micronutrient-rich diet by utilising traditional breeding practises and sophisticated biotechnological tools. To enhance the profile of rice grain for biofortification-related properties, researchers must first understand the genetics of critical biofortification characteristics. Significant increases in micronutrients like iron and zinc, as well as many other important minerals and provitamins are acquired in rice grain using the biofortification strategies. Most indica and japonica rice types have been biofortified over the world, giving them the titles of high iron rice, low phytate rice, high zinc rice, and high carotenoid rice or golden rice. Some of the recent approaches towards rice biofortification, as well as their effects, have been explored in this article.

Identification of Bee Forage Plants by Pollen Analysis of <i>Apis cerana</i> Honey Collected from Tropical Areas of Tumkur District, Karnataka, India

The present work refers to the pollen analysis of 10 honey samples collected from 4 different locations of Tumkur district, Karnataka State, India. The honey samples were collected from the domestic bee hives of Apis cerana, subjected to physico-chemical and pollen analysis to determine color, optical density and botanical origin of honey. The color of the honey sample varies from light yellow to dark red color and optical density of honey samples varies from 0.258 to 0.991. Pollen analysis indicated that the study areas comprised of diverse bee flora. Out of 10 samples analyzed, the predominant pollen types were identified in 6 samples, where Mimosa pudica was represented in 2 samples. Cocos nucifera, Mangifera indica, Eucalyptus globulus and Syzygium cumini pollen types were reported as predominant pollen from one sample each and making these honey unifloral. The remaining 4 samples were multifloral where predominant pollen types were not identified. From the results, it is clear that the factors like vegetation, pollen spectra and chemical analysis revealed a lot of potentiality in establishing bee keeping industries in the study areas. Beekeeping is an added source of income to amplify the economic upliftment without much investment.

Understanding the Palatability, Flavor, Starch Functional Properties and Storability of Indica-Japonica Hybrid Rice.

The rice quality and starch functional properties, as well as the storability of three YY-IJHR cultivars, which included YY12 (biased japonica type YY-IJHR), YY1540 (intermedius type YY-IJHR) and YY15 (biased indica type YY-IJHR), were studied and compared to N84 (conventional japonica rice). The study results suggested that the three YY-IJHR varieties all had greater cooking and eating quality than N84, as they had lower amylose and protein content. The starch of YY-IJHR has a higher pasting viscosity and digestibility, and there was a significant difference among the three YY-IJHR cultivars. Rice aroma components were revealed by GC-IMS, which indicated that the content of alcohols vola-tile components of YY-IJHR were generally lower, whereas the content of some aldehydes and esters were higher than N84. In addition, YY-IJHR cultivars’ FFA and MDA contents were lower, which demonstrated that YY-IJHR had a higher palatability and storability than those of N84 in fresh rice and rice stored for 12 months. In conclusion, this study suggested that YY-IJHR had better rice quality and storability than N84. PCA indicated that the grain quality and storability of YY12 and YY15 were similar and performed better than YY1540, while the aroma components and starch functional properties of YY-IJHR cultivars all had significant differences.

Metabolomic Analysis Reveals Insights into Deterioration of Rice Quality during Storage.

To determine the changes in the quality of rice during storage, this study investigated the comprehensive metabolomic profiles of Nanjing 9108 (typical japonica rice) and Jianzhen 2 (typical indica rice) varieties in China, using metabolomics. A total of 13 categories of 593 metabolites including lipids (134 species), phenolic acids (78 species), flavonoids (70 species), alkaloids (67 species), organic acids (64 species), amino acids and derivatives (64 species), saccharides and alcohols (44 species), nucleotides and derivatives (37 species), vitamins (14 species), lignans and coumarins (9 species), tannins (2 species), terpenoids (2 species), and others (8 species) were identified in both varieties. The result showed significant changes in 204 metabolites in Nanjing 9108, while only 26 were altered in Jianzhen 2 during storage. These metabolites involved 46 metabolic pathways. The TCA cycle, linoleic, and α-linolenic acid metabolic pathways were unique in Nanjing 9108. Finally, the results of quantitative mass spectrometry of 11 metabolites provided insight into biomarkers associated with quality deterioration of rice. This study provides insights into the mechanism of deterioration in the quality of rice during storage.

Phenotyping and Association Analysis of Zinc Biofortified Rice Varieties for Grain Yield and Quality Traits

A set of 25 test genotypes including 11 promising high zinc landraces, four zinc biofortified released varieties, six Zn-dense advance breeding lines, one OUAT rice variety, one zinc dense check variety “Chittimatyalu” and three low zinc mega varieties of rice (Swarna and Sambamahsuri) were assessed for grain Zn content and inter-relationship among seed yield and quality traits. P44 selection revealed highest Zn content (52.7ppm) followed by Basudha, Manika, Nikipankhia, ORCZ 75-3-1 and Tikimashuri with Zn content more than 40 ppm. Grain yield showed a significant positive correlation with a number of ear-bearing tillers m-2 and grain number panicle-1. Plant height exhibited a negative correlation with a number of effective bearing tillers m-2 and seed yield, but positively correlated with zinc content which seems to be the major hindrance for breeding semi-dwarf high yielding Zn-dense. The tall indica landraces such as Malliphulajhulli (43.8 ppm), Nikipankhia (42.8 ppm), Padmavati (31.3 ppm), Tikimahsuri (41.5 ppm), and Basudha (44.4 ppm) harbor high grain zinc content but revealed low yield potential. Transfer of zinc transporter genes available in the above tall indica types to semi-dwarf plant types may enrich the status of zinc content in grain.

Genetic studies for grain quality traits and correlation analysis of mineral element contents on Al-Ahsa rice and some different varieties (Oryza Sativa L.)

One of the most significant goals in plant breeding programs is to generate new rice varieties with increased elements and good grain quality. In this experiment, ten rice genotypes were evaluated for grain quality traits and protein percentage. Also, milled rice of the ten genotypes were used for analysis of mineral elements. The results revealed that mean squares attributable to genotypes were significant for all traits during the two growing seasons, showing the presence of broad genetic variability among genotypes for all traits under consideration. However, the Indica type (Egyptian Yasmin and Giza 182) gave the highest value for grain length (7.10, 6.52 mm) and grain shape (2.87, 2.82 mm) under the two seasons. While, Al-Ahsa Type1 and Al-Ahsa Type2 rice varieties gave the highest values in protein percentage, which gave 10.80 and 9.80%. Correlation coefficients among the nine grain quality traits clarifying eight absolute positive correlation grain length with grain shape, grain width with hulling % and head rice %; grain shape with amylose content %; hulling % with milled rice and head rice %; milled rice % with head rice %; head rice % with gelatinization temperature. On the other hand, there were seven absolute negative correlations between grain length with grain width; grain width with grain shape and amylose content %; grain shape with hulling % and head rice %; amylose content % with milled rice %, head rice % and gelatinization temperature. In micronutrient elements Al-Ahsa Type1 and Al-Ahsa Type2 varieties gave the heights value for N, P, K, Mg %. Also, gave the heights value for Na (73.25, 73), Fe (20.12, 19.80), and Zn (125.60, 122.70). Pearson’s correlation observed eight absolute positive and significant correlations, which were between; nitrogen content (N), P, K, Mg, Na, Fe, Zn, Cu and protein percentage.

The complete chloroplast genome of weedy rice Oryza sativa f. spontanea

The emergence of weedy rice (Oryza sativa f. spontanea) has been considered as a serious global agricultural problem in recent decades. To better understand its speciation, here we assembled the complete chloroplast genome of O. sativa f. spontanea with the length of 134,502 bp. The assembly contains a large single-copy (LSC, 80,549 bp), a small single-copy (SSC, 12,347 bp) and a pair of inverted repeats (IRa and IRb, 20,803 bp each). A total of 132 unique genes were annotated, including 82 protein-coding genes, 42 tRNA genes and eight rRNA genes. Phylogenetic analysis showed that O. sativa f. spontanea (indica type) appears closely related to cultivated indica rice rather than wild rice, supporting the hypothesis that weedy rice originated from cultivated rice.

Molecular, physiological and infection behaviour studies of Rhizoctonia solani causing the Rice Sheath Blight disease

Rhizoctonia solani is the causal agent of rice sheath blight, which is one of the most serious diseases of rice worldwide. In this study, seventeen Egyptian isolates of sheath blight pathogen, R. solani AG1 IA, were identified using morphological and molecular characterization by the internal transcribed spacer (ITS) sequences. Extracellular enzymes were assessed in in vitro and in infected rice samples. Also, pathogenicity tests for all isolates were done on two rice cultivars under greenhouse conditions. Growth behavior by RS13 isolate was studied using two rice cultivar Sakha 101 (Japonica type) and Egyptian Yasmine (Indica type). The obtained results exhibited a wide range of variability in the morphological and virulence characteristics of isolates. Two isolates RS10 and RS13 (AB5) were sequenced and found aligned with Egyptian and Chinese isolates. RS13 and RS10 isolates exhibit the highest production of cellulase, pectinase and amylase enzymes in plate culture (in vitro). While, on the plant sample tissue cellulase and pectin methylesterase (PME) activity enzymes are relating to development of rice sheath blight disease. Under the artificial condition, SK 101 rice proved the most susceptible to infection with sheath blight pathogen compare with E. Yasmine. The hyphae growth on SK101 cultivar was more than in the E. Yasmine cultivar. Furthermore, we examined the morphological developments of hyphae and sclerotial on both cultivars using light and scanning electron microscopy (SEM). It was observed that the fungal pathogen could intercept host surface structures for improving cell penetration and anchorage.

Spatial Analysis of Agronomic Data and UAV Imagery for Rice Yield Estimation

In this study, a spatial analysis of agronomic and remote sensing data is carried out to derive accurate rice crop yield estimation. The variability of a series of vegetation indices (VIs) was calculated from remote sensing data obtained via a commercial UAS platform (e-Bee) at four dates (per stage of development), and the development of estimation models was conducted. The study area is located in the region of Chalastra (municipality of Thessaloniki, North Greece) and the primary data were obtained during the 2016 growing season. These data include ultra-high resolution remote sensing multispectral images of 18 plots totaling 58 hectares of Ronaldo and Gladio rice crop varieties, 97 sample point data related to yield, and many other pieces of information recorded in the producer’s field log. Ten simple and compound VIs were calculated, and the evolution of their values during the growing season as well as their comparative correlation were studied. A study of the usability of each VI was conducted for the different phenological stages of the cultivation and the variance of VIs and yield; the more correlated VIs were identified. Furthermore, three types of multitemporal VI were calculated from combinations of VIs from different dates, and their contribution to improving yield prediction was studied. As Ronaldo is a Japonica type of rice variety and Gladio is Indica type, they behave differently in terms of maturation time (Gladio is approximately 20 days earlier) and the value of every VI is affected by changes in plant physiology and phenology. These differences between the two varieties are reflected in the multitemporal study of the single-date VIs but also in the study of the values of the multitemporal VIs. In conclusion, Ronaldo’s yield is strongly dependent on multitemporal NDVI (VI6th July + VI30 Aug, R2 = 0.76), while Gladio’s yield is strongly dependent on single-date NDVI (6 July, R2 = 0.88). The compound VIs RERDVI and MCARI1 have the highest yield prediction (R2 = 0.77) for Ronaldo (VI6th July + VI30 Aug) and Gladio (R2 = 0.95) when calculated in the booting stage, respectively. For the Ronaldo variety, the examination of the multitemporal VIs increases yield prediction accuracy, while in the case of the Gladio variety the opposite is observed. The capabilities of multitemporal VIs in yield estimation by combining UAVs with more flights during the different growth stages can improve management and the cultivation practices.

Weedy rice de‐domesticated from cultivated rice has evolved strong resistance to seed ageing

AbstractWeed seeds generally have stronger ageing resistance than crops, allowing them to maintain their persistence in the field. Weedy rice (Oryza sativa), de‐domesticated from cultivated rice (Oryza sativa L.), has become a pernicious weed in Chinese rice fields in recent years. Whether weedy rice rapidly evolved strong resistance to seed ageing in the process of de‐domestication, thereby contributing to its persistence in the paddy field, requires investigation. Accordingly, the seeds of weedy rice populations and their co‐existing rice varieties were collected from 61 regions of China and germinated after incubation at normal (25°C) and artificial accelerated ageing (50°C) conditions, for four consecutive years (2013–2016). The results showed that the seed‐ageing resistance of weedy rice was higher than that of its coexisting rice cultivars. The high temperature treatment and seed viability tests showed that weedy rice seeds had only weak dormancy in the first year (2013). Furthermore, a negative correlation was found between germination and latitude. At about 35° N, naturally selected weedy rice formed two distinct groups. This implies that indica–japonica differentiation might affect the ageing resistance of weedy rice and the coexisting cultivated rice. After dividing the weedy and cultivated rice into indica and japonica types, the germination percentage of the indica‐type was higher than that of the japonica type. These results indicate that weedy rice may have evolved new resistance to seed ageing that may be helpful in formulating prevention and control strategies for this problematic weed.

COMPARATIVE STUDIES OF SOME AGRONOMIC AND GRAIN QUALITY TRAITS FOR THREE NEW DEVELOPED RICE VARIETIES

This study was conducted at Rice Department farm, Sakha Agriculture Research Station during 2018 and 2019 seasons. Yield and yield components, grain quality, cooking quality, chemical composition with nutrition content were estimated in this study for two Egyptian varieties (Sakha 108 and Giza 182) and introduced Black Rice variety. The results showed that, Sakha 108 variety had the best grain quality characters (hulling %, milling% and head rice %) with high performance of grain yield. Giza 182 as indica type gave the good performance in yield and yield attributes. Black rice as introduced one had high levels of protein, ash, oil and minerals (iron, calcium and zinc) as nutritional elements compared with the other two varieties in both seasons, while the fiber crud percentage reached to the maximum for Sakha 108 in brown grains while the total carbohydrate was high in milled grains of Sakha 108. On the other hand, Giza 182 variety milled grains recorded the lowest content of minerals except for Ca. For cooking quality characters, results indicated that milled grains of Giza 182 gave the highest value of water uptake and produced the greatest volume expansion. Sakha 108 and Giza 182 brown and milled grains had the same time for cooking, while Black Rice variety grains gave the highest value for cooking time.