Diagnóstico taxonómico de la familia tenuipalpidae (acari: tetranychoidea) en el valle del cauca (colombia)

Varias especies de ácaros de la familia Tenuipalpidae, especialmente las del géneroBrevipalpus Donnadieu, son reconocidas como vectores de enfermedades viralesen diferentes cultivos comerciales. La falta de estudios taxonómicos en esta familiade ácaros en Colombia y la posibilidad de introducir en forma accidental especiesde estos ácaros planos, son una amenaza para la bioseguridad de la producciónfrutícola del país. El objetivo de este trabajo es contribuir a la identificación de lasespecies de Tenuipalpidae en la vegetación silvestre y cultivada en el departamentodel Valle del Cauca y confirmar la identidad taxonómica de las especies deBrevipalpus en cítricos, guayaba, maracuyá, café y orquídeas. Las recoleccionesde ejemplares se realizaron en épocas seca y lluviosa en varios municipios deldepartamento. El montaje de los ácaros se realizó en medio Hoyer. La especiepredominante en todas las localidades y en los hospedantes recolectados fueBrevipalpus phoenicis Geijskes (1939). Por el contrario, B. obovatus Donnadieuse encontró en poblaciones muy bajas en limón Tahití y mandarina en algunaslocalidades de Palmira. Tenuipalpus anacardii De León se presentó en Anacardiumexcelsum (Bertero y Balb. ex Kunth) Skeels, en el municipio de Roldanillo y T.pacificus Baker se encontró en el corregimiento de Rozo, municipio de Palmira,sobre plantas importadas de un cultivo comercial de Dendrobium sp., mientrasque Dolichotetranychus floridanus (Banks) solamente se encontró sobre Ananascomosus (L.) Merr., en muestras recolectadas en Cal

Estimating rice yield related traits and quantitative trait loci analysis under different nitrogen treatments using a simple tower-based field phenotyping system with modified single-lens reflex cameras

CIAT- Outstanding Research Publication Award (ORPA) - 2017Application of field based high-throughput phenotyping (FB-HTP) methods for monitoring plant performance in real field conditions has a high potential to accelerate the breeding process. In this paper, we discuss the use of a simple tower based remote sensing platform using modified single-lens reflex cameras for phenotyping yield traits in rice under different nitrogen (N) treatments over three years. This tower based phenotyping platform has the advantages of simplicity, ease and stability in terms of introduction, maintenance and continual operation under field conditions. Out of six phenological stages of rice analyzed, the flowering stage was the most useful in the estimation of yield performance under field conditions. We found a high correlation between several vegetation indices (simple ratio (SR), normalized difference vegetation index (NDVI), transformed vegetation index (TVI), corrected transformed vegetation index (CTVI), soil-adjusted vegetation index (SAVI) and modified soil-adjusted vegetation index (MSAVI)) and multiple yield traits (panicle number, grain weight and shoot biomass) across a three trials. Among all of the indices studied, SR exhibited the best performance in regards to the estimation of grain weight (R2 = 0.80). Under our tower-based field phenotyping system (TBFPS), we identified quantitative trait loci (QTL) for yield related traits using a mapping population of chromosome segment substitution lines (CSSLs) and a single nucleotide polymorphism data set. Our findings suggest the TBFPS can be useful for the estimation of yield performance during early crop development. This can be a major opportunity for rice breeders whom desire high throughput phenotypic selection for yield performance traits

DIAGNÓSTICO TAXONÓMICO DE LA FAMILIA TENUIPALPIDAE (ACARI: TETRANYCHOIDEA) EN EL VALLE DEL CAUCA (COLOMBIA)

Varias especies de ácaros de la familia Tenuipalpidae, especialmente las del géneroBrevipalpus Donnadieu, son reconocidas como vectores de enfermedades viralesen diferentes cultivos comerciales. La falta de estudios taxonómicos en esta familiade ácaros en Colombia y la posibilidad de introducir en forma accidental especiesde estos ácaros planos, son una amenaza para la bioseguridad de la producciónfrutícola del país. El objetivo de este trabajo es contribuir a la identificación de lasespecies de Tenuipalpidae en la vegetación silvestre y cultivada en el departamentodel Valle del Cauca y confirmar la identidad taxonómica de las especies deBrevipalpus en cítricos, guayaba, maracuyá, café y orquídeas. Las recoleccionesde ejemplares se realizaron en épocas seca y lluviosa en varios municipios deldepartamento. El montaje de los ácaros se realizó en medio Hoyer. La especiepredominante en todas las localidades y en los hospedantes recolectados fueBrevipalpus phoenicis Geijskes (1939). Por el contrario, B. obovatus Donnadieuse encontró en poblaciones muy bajas en limón Tahití y mandarina en algunaslocalidades de Palmira. Tenuipalpus anacardii De León se presentó en Anacardiumexcelsum (Bertero y Balb. ex Kunth) Skeels, en el municipio de Roldanillo y T.pacificus Baker se encontró en el corregimiento de Rozo, municipio de Palmira,sobre plantas importadas de un cultivo comercial de Dendrobium sp., mientrasque Dolichotetranychus floridanus (Banks) solamente se encontró sobre Ananascomosus (L.) Merr., en muestras recolectadas en Cali</div

Population parameters and damage of Polyphagotarsonemus latus (Acari: Tarsonemidae) in Valencia orange (Citrus sinensis [L.] Osbeck) crop

Polyphagotarsonemus latus is one a major pest of Valencia orange in Colombia. To study its biology, it was established an experiment on young leaves of the Valencia orange at 25 ± 5°C, 70 ± 5% RH, and 12:12 L:D photoperiod. To characterize the nature of damage caused by this mite on leaves and young fruits, a trial in screenhouse conditions using young leaf and small fruits (0.1 - 0.3 cm in diameter) and fruits between 1.0–3.0 cm in diameter, which were infested with 5, 15 and 30 adult females of P. latus, was established. The total duration of life cycle was 3.2 days; the female had an oviposition period of 7.4 days and longevity 9.6 days. Life table parameters were as follows: net reproductive rate (Ro) = 93.3, intrinsic rate of natural increase (rm) = 1.2, finite multiplication rate (λ) = 3.7, doubling time (TD) = 0.6 days and generation time (T) = 3.4. The first signs of damage and shoot drop in newly developed shoots occurred between 7.0 and 11.8 days after infestation. Small fruit infested with 5-30 mites showed damage 2.4 days after infestation. Shoot drop started 7.0 days after infestation. In the case of fruits between 1.0 and 3.0 cm in diameter, the damage and the collapse of the structure was between 3.0 and 13.5 days, respectively. These results explain how a mite with a very short life cycle and huge biotic potential causes such severe damage in shoots and newly formed fruits of Valencia orange

Identification of QTLs associated with agronomic performance under nitrogen-deficient conditions using chromosome segment substitution lines of a wild rice relative, Oryza rufipogon

Improved root system architecture can enhance agronomic performance by increasing water and nitrogen (N) acquisition efficiency. However, little is known about interaction between root system architecture and agronomic performance under field environments. To gain a better understanding about the genetic basis of these relationships, we evaluated a set of chromosome segment substitution lines (CSSLs) derived from crosses between a tropical japonica rice cultivar ‘Curinga’ and a wild species Oryza rufipogon accession IRGC105491. Root system architectural traits were investigated using the CSSLs at 40 days old seedlings using the root basket method under hydroponic conditions, and agronomic performances were also tested under field conditions with different N treatments. Agronomic performances were computed as the ratio of a trait value under low to high N treatments, including grain yield and biomass yield as nitrogen-deficiency tolerance (NDT) traits. Root architecture and NDT trait QTLs were mapped using 238 SNP marker loci. A total of 13 QTLs for root system architectural, NDT and morpho-physiological traits were identified on chromosomes 1, 3, 4, 5, 7, 8, 9, 10 and 12. Interestingly, a QTL for deeper root number was identified the region of SNP markers between id1012330 and id1021697 on chromosome 1 under hydroponic conditions overlapped with a QTL for NDT trait of relative grain yield (qRGY1). These results suggest that deeper root trait is helpful to maintain grain yield under nitrogen-deficient conditions. The QTL associated root architecture could potentially be used in future rice-breeding efforts to increase agronomic performance under nitrogen-deficient conditions

Comparative Analysis of Detectors and Feature Descriptors for Multispectral Image Matching in Rice Crops

Precision agriculture has greatly benefited from advances in machine vision and image processing techniques. The use of feature descriptors and detectors allows to find distinctive keypoints in an image and the use of this approach for agronomical applications has become a widespread field of study. By combining near infrared (NIR) images, acquired with a modified Nikon D80 camera, and visible spectrum (VIS) images, acquired with a Nikon D300s, a proper crop identification could be obtained. Still, the use of different sensors brings an image matching challenge due to the difference between cameras and the possible distortions from each imaging technique. The aim of this paper is to compare the performance of several feature descriptors and detectors by comparing near infrared and visual spectral bands in rice crop images. Therefore, a group of 20 different scenes with different cameras and growth stages in a rice crop were evaluated. Thus, red, green, blue (RGB) and L, a, b (CIE L*a*b*) channels were extracted from VIS images in order to compare the matches obtained between each of them and the corresponding NIR image. The BRISK, SURF, SIFT, ORB, KAZE, and AKAZE methods were implemented, which act as descriptors and detectors. Additionally, a combination was made between the FAST algorithm for the detection of keypoints with the BRIEF, BRISK, and FREAK methods for features description. BF and FLANN matching methods were used. The algorithms were implemented in Python using OpenCV library. The green channel presented the highest number of correct matches in all methods. In turn, the method that presented the highest performance both in time and in the number of correct matches was the combination of the FAST feature detector and the BRISK descriptor

Comparison Between Rice Plant Traits and Color Indices Calculated from UAV Remote Sensing Images

Remote sensing technology for monitoring plant trains has a huge potential to accelerate breeding process. In this paper, we have studied on remote sensing of using an unmanned aerial vehicle (UAV) system for plant traits phenotyping in rice. The images of rice canopy were taken by a RGB camera from the UAV at three growing stages; Vegetative (VG), Flowering (FW) and Grain filling (GF). Typical color indices (r, g, b, INT, VIG, L*, a*, b*, H) were calculated by image processing. Single regression analysis was conducted between rice plant traits (leaf area index (LAI), grain yield, above ground biomass, plant height, panicle length, grain filling rate, tiller number) and color indices. The index a* at FW and GF had close liner relationships with LAI (the coefficient of determination R2 > 0.70) and grain yield (R2 > 0.50). Moreover, a* and g at FW and GF showed high R2 with plant height and grain filling rate (R2 > 0.50). The R2 between grain yield and color indices increased above 0.5 for about 40% of models at three growing stages by multiple regression analysis. In particular, the models of H and INT and of H and L* at VG were closely related (R2 > 0.70). Our findings show the analysis of color images taken by UAV remote sensing is useful to assessing four rice traits; LAI, grain yield, plant height and grain filling rate at early stage, and especially more available for grain yield estimation

Development and field performance of nitrogen use efficient rice lines for Africa

Nitrogen (N) fertilizers are a major input cost in rice production, and its excess application leads to major environmental pollution. Development of rice varieties with improved nitrogen use efficiency (NUE) is essential for sustainable agriculture. Here, we report the results of field evaluations of marker-free transgenic NERICA4 (New Rice for Africa 4) rice lines overexpressing barley alanine amino transferase (HvAlaAT) under the control of a rice stress-inducible promoter (pOsAnt1). Field evaluations over three growing seasons and two rice growing ecologies (lowland and upland) revealed that grain yield of pOsAnt1:HvAlaAT transgenic events was significantly higher than sibling nulls and wild-type controls under different N application rates. Our field results clearly demonstrated that this genetic modification can significantly increase the dry biomass and grain yield compared to controls under limited N supply. Increased yield in transgenic events was correlated with increased tiller and panicle number in the field, and evidence of early establishment of a vigorous root system in hydroponic growth. Our results suggest that expression of the HvAlaAT gene can improve NUE in rice without causing undesirable growth phenotypes. The NUE technology described in this article has the potential to significantly reduce the need for N fertilizer and simultaneously improve food security, augment farm economics and mitigate greenhouse gas emissions from the rice ecosystem

Overexpression of an Arabidopsis thaliana galactinol synthase gene improves drought tolerance in transgenic rice and increased grain yield in the field

Drought stress has often caused significant decreases in crop production which could be associated with global warming. Enhancing drought tolerance without a grain yield penalty has been a great challenge in crop improvement. Here, we report the Arabidopsis thaliana galactinol synthase 2 gene (AtGolS2) was able to confer drought tolerance and increase grain yield in two different rice (Oryza sativa) genotypes under dry field conditions. The developed Ubi:AtGolS2 transgenic lines also had higher levels of galactinol than the non-transgenic control. The increased grain yield of the transgenic rice under drought conditions was related to a higher number of panicles, grain fertility and biomass. Extensive confined field trials using transgenic lines expressing AtGolS2 under the control of the constitutive maize ubiquitin promoter (Ubi:AtGolS2) in Curinga, tropical japonica and NERICA4, interspecific hybrid across two different seasons and environments revealed the verified lines have the proven field drought tolerance of the Ubi:AtGolS2 transgenic rice. The amended drought tolerance was associated with higher relative water content of leaves, higher photosynthesis activity, lesser reduction in plant growth and faster recovering ability. Collectively, our results provide strong evidence that AtGolS2 is a useful biotechnological tool to reduce grain yield losses in rice beyond genetic differences under field drought stress