Low fertilizer inputs do not adversely affect yield or performance of Indica hybrid rice

The enhancement of rice production numbers can be achieved by using quality rice cultivars and fertilizers. The double rice cropping model has given rise to an important rice production system in southern China. Exploring the possibility of whether hybrid vigor could make a substantial contribution to early and late season rice production, and how the heterosis expression of hybrid rice functions under different levels of fertilizer application is of great significance. The objective of this study was to evaluate the grain yield and associated plant traits of popular hybrid and inbred rice varieties with large-scale promotion under conditions of customary (high) and combined (low) fertilization in the early and late seasons of 2017-18 in Changsha County, Hunan Province, China. We found that hybrid rice varieties displayed their respective advantages in the early and late rice seasons, but the advantages in their relative yield traits varied. The leading advantages of early season rice were effective panicle number per hill (EPN), 1000-grain weight (KGW), harvest index (HI), yield, and nitrogen use efficiency (NUE), whereas in late season rice, the foremost advantages were grain number per panicle (GNP), HI, yield, and NUE. The EPN was the prime advantage of early season hybrid rice with a short growth period, and the GNP was the main advantage of late season hybrid rice with a long growth period. Notably, the main yield advantage of hybrid rice was stronger under combined (low) fertilization than under customary (high) fertilization. Hence, high yield can be achieved by selecting the best hybrid rice varieties supported by combined fertilization (lower fertilizer use with higher efficiency).

Genetic diversity and heterotic grouping of sorghum lines using SNP markers

Sorghum breeding programs are based predominantly on developing homozygous lines to produce single cross hybrids, frequently with relatively narrow genetic bases. The adoption of complementary strategies, such as genetic diversity study, enables a broader vision of the genetic structure of the breeding germplasm. The purpose of this study was to evaluate the genetic diversity of sorghum breeding lines using structure analysis, principal components (PC) and clustering analyses. A total of 160 sorghum lines were genotyped with 29,649 SNP markers generated by genotyping-by-sequencing (GBS). The PC and clustering analyses consistently divided the R (restorer) and B (maintainer) lines based on their pedigree, generating four groups. Thirty-two B and 21 R lines were used to generate 121 single-cross hybrids, whose performances were compared based on the diversity clustering of each parental line. The genetic divergence of B and R lines indicated a potential for increasing heterotic response in the development of hybrids. The genetic distance was correlated to heterosis, allowing for the use of markers to create heterotic groups in sorghum.(AU)

Genetic diversity and heterotic grouping of sorghum lines using SNP markers

Sorghum breeding programs are based predominantly on developing homozygous lines to produce single cross hybrids, frequently with relatively narrow genetic bases. The adoption of complementary strategies, such as genetic diversity study, enables a broader vision of the genetic structure of the breeding germplasm. The purpose of this study was to evaluate the genetic diversity of sorghum breeding lines using structure analysis, principal components (PC) and clustering analyses. A total of 160 sorghum lines were genotyped with 29,649 SNP markers generated by genotyping-by-sequencing (GBS). The PC and clustering analyses consistently divided the R (restorer) and B (maintainer) lines based on their pedigree, generating four groups. Thirty-two B and 21 R lines were used to generate 121 single-cross hybrids, whose performances were compared based on the diversity clustering of each parental line. The genetic divergence of B and R lines indicated a potential for increasing heterotic response in the development of hybrids. The genetic distance was correlated to heterosis, allowing for the use of markers to create heterotic groups in sorghum.

Root morphological traits of oil palm genotypes with differential resistance to fatal yellowing / Características morfológicas radiculares de genótipos de palma de óleo com resistência diferencial ao Amarelecimento Fatal

Brazil has an extensive area where the climate and soil are suitable for oil palm growing. However, in part of this area, production has been limited by the occurrence of the fatal yellowing (FY) anomaly, whose initial symptom is the rotting of absorptive roots. This symptom can be more severe in oil palm genetic materials with a smaller root system. The aim of this study was to examine morphological traits of roots and shoots of seedlings of three oil palm genotypes with different degrees of resistance to FY, namely, Tenera (sensitive), Caiaué (resistant) and Interspecific Hybrid (resistant) to provide bases to elucidate the differential resistance of these materials to FY. Shoot biomass did not vary statistically between the genetic materials. The mass, length and area of fine and very fine roots were significantly higher in the Interspecific Hybrid than in Caiaué and Tenera. The fine and very fine roots of Interspecific Hybrid had a larger mass than Caiaué (114 and 133%, respectively) and Tenera (216 and 178%, respectively). The Interspecific Hybrid also exhibited higher values for the length of fine and very fine roots than Caiaué (155 and 99% respectively) and Tenera (228 and 94% respectively). The root traits of the Interspecific Hybrid and Tenera are compatible with their differential resistance to FY. Our results demonstrate the importance of expanding the study of the relationship between root morphology and resistance to FY in these genetic materials under conditions that favor the occurrence of the anomaly, such as flooding.

O Brasil possui uma extensa área com clima e solo aptos ao plantio de palma de óleo. No entanto, a produção em parte desta área tem sido limitada pela ocorrência da anomalia Amarelecimento Fatal (AF),cujo sintoma inicial é o apodrecimento das raízes de absorção. Esse sintoma pode ser mais severo em materiais genéticos de palma de óleo que apresentem sistema radicular reduzido. O objetivo foi avaliar características morfológicas de raízes e parte aérea de mudas de três genótipos de palma de óleo com graus diferentes de resistência ao AF: Tenera (sensível), Caiaué (resistente) e Híbrido Interespecífico (resistente)para fornecer subsídios ao entendimento da resistência diferencial desses materiais ao AF. A biomassa da parte aérea não variou estatisticamente entre os materiais genéticos. Massa, comprimento e área de raízes finas e muito finas foram significativamente maiores no Híbrido Interespecífico do que no Caiaué e no Tenera. O Híbrido Interespecífico apresentou valores de massa de raízes finas e muito finas superiores em relação ao Caiaué (114 e 133%, respectivamente) e Tenera (216 e 178%, respectivamente). O Híbrido Interespecífico também apresentou valores superiores de comprimento de raízes finas e muito finas em relação ao Caiaué (155 e 99% respectivamente) e Tenera (228 e 94% respectivamente). As características radiculares do Híbrido Interespecífico e do Tenera são compatíveis com sua resistência diferencial ao AF. Nossos resultados demonstram a importância de ampliar o estudo da relação entre morfologia radicular e resistência ao AF destes materiais genéticos em condições que favoreçam a ocorrência da anomalia, como alagamento.

Root morphological traits of oil palm genotypes with differential resistance to fatal yellowing / Características morfológicas radiculares de genótipos de palma de óleo com resistência diferencial ao Amarelecimento Fatal

Brazil has an extensive area where the climate and soil are suitable for oil palm growing. However, in part of this area, production has been limited by the occurrence of the fatal yellowing (FY) anomaly, whose initial symptom is the rotting of absorptive roots. This symptom can be more severe in oil palm genetic materials with a smaller root system. The aim of this study was to examine morphological traits of roots and shoots of seedlings of three oil palm genotypes with different degrees of resistance to FY, namely, Tenera (sensitive), Caiaué (resistant) and Interspecific Hybrid (resistant) to provide bases to elucidate the differential resistance of these materials to FY. Shoot biomass did not vary statistically between the genetic materials. The mass, length and area of fine and very fine roots were significantly higher in the Interspecific Hybrid than in Caiaué and Tenera. The fine and very fine roots of Interspecific Hybrid had a larger mass than Caiaué (114 and 133%, respectively) and Tenera (216 and 178%, respectively). The Interspecific Hybrid also exhibited higher values for the length of fine and very fine roots than Caiaué (155 and 99% respectively) and Tenera (228 and 94% respectively). The root traits of the Interspecific Hybrid and Tenera are compatible with their differential resistance to FY. Our results demonstrate the importance of expanding the study of the relationship between root morphology and resistance to FY in these genetic materials under conditions that favor the occurrence of the anomaly, such as flooding.(AU)

O Brasil possui uma extensa área com clima e solo aptos ao plantio de palma de óleo. No entanto, a produção em parte desta área tem sido limitada pela ocorrência da anomalia Amarelecimento Fatal (AF), cujo sintoma inicial é o apodrecimento das raízes de absorção. Esse sintoma pode ser mais severo em materiais genéticos de palma de óleo que apresentem sistema radicular reduzido. O objetivo foi avaliar características morfológicas de raízes e parte aérea de mudas de três genótipos de palma de óleo com graus diferentes de resistência ao AF: Tenera (sensível), Caiaué (resistente) e Híbrido Interespecífico (resistente) para fornecer subsídios ao entendimento da resistência diferencial desses materiais ao AF. A biomassa da parte aérea não variou estatisticamente entre os materiais genéticos. Massa, comprimento e área de raízes finas e muito finas foram significativamente maiores no Híbrido Interespecífico do que no Caiaué e no Tenera. O Híbrido Interespecífico apresentou valores de massa de raízes finas e muito finas superiores em relação ao Caiaué (114 e 133%, respectivamente) e Tenera (216 e 178%, respectivamente). O Híbrido Interespecífico também apresentou valores superiores de comprimento de raízes finas e muito finas em relação ao Caiaué (155 e 99% respectivamente) e Tenera (228 e 94% respectivamente). As características radiculares do Híbrido Interespecífico e do Tenera são compatíveis com sua resistência diferencial ao AF. Nossos resultados demonstram a importância de ampliar o estudo da relação entre morfologia radicular e resistência ao AF destes materiais genéticos em condições que favoreçam a ocorrência da anomalia, como alagamento.(AU)

Root morphological traits of oil palm genotypes with differential resistance to fatal yellowing / Características morfológicas radiculares de genótipos de palma de óleo com resistência diferencial ao Amarelecimento Fatal

Brazil has an extensive area where the climate and soil are suitable for oil palm growing. However, in part of this area, production has been limited by the occurrence of the fatal yellowing (FY) anomaly, whose initial symptom is the rotting of absorptive roots. This symptom can be more severe in oil palm genetic materials with a smaller root system. The aim of this study was to examine morphological traits of roots and shoots of seedlings of three oil palm genotypes with different degrees of resistance to FY, namely, Tenera (sensitive), Caiaué (resistant) and Interspecific Hybrid (resistant) to provide bases to elucidate the differential resistance of these materials to FY. Shoot biomass did not vary statistically between the genetic materials. The mass, length and area of fine and very fine roots were significantly higher in the Interspecific Hybrid than in Caiaué and Tenera. The fine and very fine roots of Interspecific Hybrid had a larger mass than Caiaué (114 and 133%, respectively) and Tenera (216 and 178%, respectively). The Interspecific Hybrid also exhibited higher values for the length of fine and very fine roots than Caiaué (155 and 99% respectively) and Tenera (228 and 94% respectively). The root traits of the Interspecific Hybrid and Tenera are compatible with their differential resistance to FY. Our results demonstrate the importance of expanding the study of the relationship between root morphology and resistance to FY in these genetic materials under conditions that favor the occurrence of the anomaly, such as flooding.(AU)

O Brasil possui uma extensa área com clima e solo aptos ao plantio de palma de óleo. No entanto, a produção em parte desta área tem sido limitada pela ocorrência da anomalia Amarelecimento Fatal (AF),cujo sintoma inicial é o apodrecimento das raízes de absorção. Esse sintoma pode ser mais severo em materiais genéticos de palma de óleo que apresentem sistema radicular reduzido. O objetivo foi avaliar características morfológicas de raízes e parte aérea de mudas de três genótipos de palma de óleo com graus diferentes de resistência ao AF: Tenera (sensível), Caiaué (resistente) e Híbrido Interespecífico (resistente)para fornecer subsídios ao entendimento da resistência diferencial desses materiais ao AF. A biomassa da parte aérea não variou estatisticamente entre os materiais genéticos. Massa, comprimento e área de raízes finas e muito finas foram significativamente maiores no Híbrido Interespecífico do que no Caiaué e no Tenera. O Híbrido Interespecífico apresentou valores de massa de raízes finas e muito finas superiores em relação ao Caiaué (114 e 133%, respectivamente) e Tenera (216 e 178%, respectivamente). O Híbrido Interespecífico também apresentou valores superiores de comprimento de raízes finas e muito finas em relação ao Caiaué (155 e 99% respectivamente) e Tenera (228 e 94% respectivamente). As características radiculares do Híbrido Interespecífico e do Tenera são compatíveis com sua resistência diferencial ao AF. Nossos resultados demonstram a importância de ampliar o estudo da relação entre morfologia radicular e resistência ao AF destes materiais genéticos em condições que favoreçam a ocorrência da anomalia, como alagamento.(AU)

Identification and phenotypic characterization of genetic groups of the Girolando breed in dairy herds of the state of Roraima / Identificação e caracterização fenotípica dos grupos genéticos da raça Girolando nos rebanhos leiteiros do estado de Roraima

Dairy farming in the state of Roraima, Brazil, is majorly supported by Holstein x Gir crossbred cattle, which are more adapted to the tropical climate and traditional production systems. However, there is a need to adapt the genetic groups to production systems and raise awareness of the importance of using visual phenotypic assessments as an auxiliary tool in obtaining and selecting animals. This study proposes to identify the frequency and characterize the phenotype of the » Hol + ¾ Gir; ⅜ Hol + ⅝ Gir; ½ Hol + ½ Gir; ⅝Hol + ⅜ Gir; ¾ Hol + » Gir; and ⅞ Hol + ⅛ Gir genetic groups of the Girolando breed in herds in the state of Roraima. Data were obtained from visual morphological evaluations to identify the genetic groups and characterize the phenotype of the animals from August 2016 to February 2017. According to the evaluations, the frequency distribution of the genetic groups was as follows: 210 (21.26%) of the » Hol + ¾ Gir group; 145 (14.68%) of the ⅜ Hol + ⅝ Gir group; 249 (25.20%) of the ½ Hol ½ Gir group; 166 (16.80%) of the ⅝ Hol + ⅜ Gir group; 126 (12.75%) of the ¾ Hol + » Gir group; and 92 (9.3%) of the ⅞ Hol + ⅛ Gir group. In the phenotypic evaluations, statistically significant differences (p<0.05) were detected in the ¾ Hol + » Gir genetic group for overall appearance (OA); in ⅝ Hol + ⅜ Gir and ⅞ Hol + ⅛ Gir for Body Capacity (BC); in ½ Hol + ½ Gir for Dairy Traits (DT); and in ¾ Hol + » Gir and ⅞ Hol + ⅛ Gir for Reproductive System and Feet-Leg Structure (RS/FL). The ½ Hol + ½ Gir genetic group was superior for BC, DT and RS/FL, being best classified as to the Girolando breed type and revealing better characterization and uniformity per selection process.

A pecuária leiteira do Estado de Roraima é sustentada por bovinos mestiços Holandês x Gir, animais mais adaptados ao clima tropical e aos sistemas de produção tradicionais. No entanto, existe a necessidade de adequação dos grupos genéticos aos sistemas de produção e de sensibilizar quanto à importância do uso de avaliações visuais fenotípicas como ferramenta de auxilio na obtenção e seleção dos animais. Os objetivos da pesquisa consistiram em identificar a frequência e caracterizar o fenótipo dos grupos genéticos » Hol + ¾ Gir, ⅜ Hol + ⅝ Gir, ½ Hol + ½ Gir, ⅝ Hol + ⅜ Gir, ¾ Hol + » Gir e ⅞ Hol + ⅛ Gir da raça Girolando nos rebanhos do Estado de Roraima. Os dados foram obtidos a partir de avaliações visuais morfológicas para identificar os grupos genéticos e caracterizar o fenótipo dos animais no período de agosto de 2016 a fevereiro de 2017. A distribuição da frequência dos grupos genéticos de acordo com as avaliações foi de: 210 (21,26%) do grupo » Hol + ¾ Gir; 145 (14,68%) do grupo ⅜ Hol + ⅝ Gir; 249 (25,20%) do grupo ½ Hol ½ Gir; 166 (16,80%) do grupo ⅝ Hol + ⅜ Gir; 126 (12,75%) do grupo ¾ Hol + » Gir e 92 (9,3%) do grupo ⅞ Hol + ⅛ Gir. Nas avaliações fenotípicas foram observadas diferenças estaticamente significativas (p<0,05) no grupo genético ¾ Hol + » Gir para Aparência Geral (AG), nos grupos genéticos ⅝ Hol + ⅜ Gir e ⅞ Hol + ⅛ Gir para Capacidade Corporal (CC), nogrupo ½ Hol + ½ Gir para Características Leiteiras (CL) e nos grupos ¾ Hol + » Gir e ⅞ Hol + ⅛ Gir para Aparelho Reprodutor e Aprumos (AR/A). O grupo genético ½ Hol + ½ Gir foi superior nas características Capacidade Corporal (CC), Características Leiteiras (CL) e Aparelho Reprodutor e Aprumos (AR/A), sendo melhores classificados quanto ao tipo da raça Girolando demonstrando melhor caracterização e uniformização por processo seletivo.

Identification and phenotypic characterization of genetic groups of the Girolando breed in dairy herds of the state of Roraima / Identificação e caracterização fenotípica dos grupos genéticos da raça Girolando nos rebanhos leiteiros do estado de Roraima

Dairy farming in the state of Roraima, Brazil, is majorly supported by Holstein x Gir crossbred cattle, which are more adapted to the tropical climate and traditional production systems. However, there is a need to adapt the genetic groups to production systems and raise awareness of the importance of using visual phenotypic assessments as an auxiliary tool in obtaining and selecting animals. This study proposes to identify the frequency and characterize the phenotype of the » Hol + ¾ Gir; ⅜ Hol + ⅝ Gir; ½ Hol + ½ Gir; ⅝Hol + ⅜ Gir; ¾ Hol + » Gir; and ⅞ Hol + ⅛ Gir genetic groups of the Girolando breed in herds in the state of Roraima. Data were obtained from visual morphological evaluations to identify the genetic groups and characterize the phenotype of the animals from August 2016 to February 2017. According to the evaluations, the frequency distribution of the genetic groups was as follows: 210 (21.26%) of the » Hol + ¾ Gir group; 145 (14.68%) of the ⅜ Hol + ⅝ Gir group; 249 (25.20%) of the ½ Hol ½ Gir group; 166 (16.80%) of the ⅝ Hol + ⅜ Gir group; 126 (12.75%) of the ¾ Hol + » Gir group; and 92 (9.3%) of the ⅞ Hol + ⅛ Gir group. In the phenotypic evaluations, statistically significant differences (p<0.05) were detected in the ¾ Hol + » Gir genetic group for overall appearance (OA); in ⅝ Hol + ⅜ Gir and ⅞ Hol + ⅛ Gir for Body Capacity (BC); in ½ Hol + ½ Gir for Dairy Traits (DT); and in ¾ Hol + » Gir and ⅞ Hol + ⅛ Gir for Reproductive System and Feet-Leg Structure (RS/FL). The ½ Hol + ½ Gir genetic group was superior for BC, DT and RS/FL, being best classified as to the Girolando breed type and revealing better characterization and uniformity per selection process.(AU)

A pecuária leiteira do Estado de Roraima é sustentada por bovinos mestiços Holandês x Gir, animais mais adaptados ao clima tropical e aos sistemas de produção tradicionais. No entanto, existe a necessidade de adequação dos grupos genéticos aos sistemas de produção e de sensibilizar quanto à importância do uso de avaliações visuais fenotípicas como ferramenta de auxilio na obtenção e seleção dos animais. Os objetivos da pesquisa consistiram em identificar a frequência e caracterizar o fenótipo dos grupos genéticos » Hol + ¾ Gir, ⅜ Hol + ⅝ Gir, ½ Hol + ½ Gir, ⅝ Hol + ⅜ Gir, ¾ Hol + » Gir e ⅞ Hol + ⅛ Gir da raça Girolando nos rebanhos do Estado de Roraima. Os dados foram obtidos a partir de avaliações visuais morfológicas para identificar os grupos genéticos e caracterizar o fenótipo dos animais no período de agosto de 2016 a fevereiro de 2017. A distribuição da frequência dos grupos genéticos de acordo com as avaliações foi de: 210 (21,26%) do grupo » Hol + ¾ Gir; 145 (14,68%) do grupo ⅜ Hol + ⅝ Gir; 249 (25,20%) do grupo ½ Hol ½ Gir; 166 (16,80%) do grupo ⅝ Hol + ⅜ Gir; 126 (12,75%) do grupo ¾ Hol + » Gir e 92 (9,3%) do grupo ⅞ Hol + ⅛ Gir. Nas avaliações fenotípicas foram observadas diferenças estaticamente significativas (p<0,05) no grupo genético ¾ Hol + » Gir para Aparência Geral (AG), nos grupos genéticos ⅝ Hol + ⅜ Gir e ⅞ Hol + ⅛ Gir para Capacidade Corporal (CC), nogrupo ½ Hol + ½ Gir para Características Leiteiras (CL) e nos grupos ¾ Hol + » Gir e ⅞ Hol + ⅛ Gir para Aparelho Reprodutor e Aprumos (AR/A). O grupo genético ½ Hol + ½ Gir foi superior nas características Capacidade Corporal (CC), Características Leiteiras (CL) e Aparelho Reprodutor e Aprumos (AR/A), sendo melhores classificados quanto ao tipo da raça Girolando demonstrando melhor caracterização e uniformização por processo seletivo.(AU)

Potential of parents and hybrids experimental of the yellow melon / Potencial de parentais e híbridos experimentais de melão amarelo

Melon or muskmelon (Cucumis melo L.) is of considerable economic importance in Brazil. Nearly all the cultivars currently grown are hybrids. Heterosis has been used to advantage in the melon plant, and the use of uniform hybrids is one of the reasons for successful cultivation. The aim of the present study was to evaluate the agronomic potential of yellow melon lines and hybrids. An experiment was conducted in randomized blocks with three replications to evaluate 24 hybrids generated by crosses among three elite lines used as female parents (AF-01, AF-02, and AF-03) and eight lines used as male parents (LAM-01, LAM-02, LAM-03, LAM-04, LAM-05, LAM-06, LAM-07, and LAM-08). Yield and fruit quality traits were evaluated. Partial diallel analysis was carried out to estimate general combining ability and specific combining ability. Additive and non-additive effects were observed for the yield, mean fruit weight, and pulp thickness traits. The lines AF-02, LAM-02, and LAM-03 are the most promising as parents as they more frequently have favorable alleles. The most prominent hybrids in diallel analysis were AF-02 x LAM-02, AF-02 x LAM-03, AF-02 x LAM-04, and AF-03 x LAM-06.(AU)

O melão amarelo (Cucumis melo L.) é uma hortaliça de grande importância econômica. Atualmente as cultivares plantadas, em quase sua totalidade, são híbridos. A heterose tem sido explorada no meloeiro, sendo o emprego de híbridos uniformes uma das razões do sucesso da cultura. O objetivo do presente trabalho foi avaliar o potencial agronômico de linhagens e híbridos de melão amarelo. Foi conduzido um ensaio em blocos casualizados com três repetições para avaliar 24 híbridos gerados pelos cruzamentos entre três linhagens elites utilizadas como genitores femininos (AF-01, AF-02 e AF-03), e oito linhagens utilizadas como genitores masculinos (LAM-01; LAM-02; LAM-03; LAM-04; LAM-05; LAM-06; LAM-07 e LAM-08). Foram avaliados caracteres a produção e a qualidade do fruto. Realizou-se a análise dialélica parcial para estimação das capacidades geral e específica de combinação. Observou-se efeitos aditivos e não aditivos para os caracteres produtividade, peso médio do fruto e espessura da polpa. As linhagens AF-02, LAM-02 e LAM03 são as mais promissoras por possuir maior frequência de alelos favoráveis. Os híbridos de maior destaque foram AF-02 x LAM-02, AF-02 x LAM-03, AF-02 x LAM-04 e AF-03 x LAM-06.(AU)

Identifying parents and generating hybrids with high combining ability for yielding fresh cocoon and raw silk in silkworm (Bombxy mori L)

This study was carried out to identify parents and hybrids by determination of general combining ability (GCA), specific combining ability (SCA), and heterosis in pure lines and their hybrids, which were selected from our gene sources, to determine new hybrid combinations that could be alternative or higher in yielding compared with M × N hybrid used in production. Combining ability and heterosis effects were studied for the eight quantitative characters through line × tester mating design. Chinese origin lines (KZ, ZF) were identified as females and Japanese origin lines (BR, ZB) as males, and by these, four hybrids were derived. M, N, and their hybrid were both used as control genotypes and to calculate the heterosis and commercial heterosis as well. All the genotypes were reared in standard conditions, in three replications. ZF (for pupa survival rate) and ZB (for hatching and filament length) presented significantly higher and positive GCA effects. In addition, ZB had negative GCA effect for infertile egg rate. Effects of SCA were not significant for all the characters. In conclusion, ZF × ZB hybrid could have a potential for the higher cocoon and silk production in Turkey.(AU)