influence of genetic and genotype x environment interaction on quality of rice grain

Rice (Oryza sativa) grain attributes, including among others milling quality, grain length and shape, amylose content, and aroma are critical in varietal development and subsquent adoption at the farm level. It is, therefore, important to understand the influence of genetic and G x E interaction on these grain attibutes. Thus, experiments were laid out during 1999-2000 at the Tanganyika Agricultural Cooperative, Ifakara (irrigated culture) and at Sokoine University of Agriculture (upland conditions) both in Morogoro region, to obtain relative magnitudes ofvariety x environment interactions, heritability and genetic advance aspects on physical and biochemical rice grain quality attributes. High significant positive genotypic and phenotypic correlations were revealed between gel consistency (GC) and both the grain length (GL) and amylose content (AC). Gel consistency had high estimatesof heritability and expected genetic advance, and is thus a reliable selection criterion for amylose content in early generations of rice improvement. The observed variation among genotypes under different environments suggest that in order to ensure high grain quality, there is need to select genotypes for particular cropping environments

Variation and inter-relationship, between yield and, some agronomic characters in induced rice (Oryza sativa L.) mutants

Tanzania Journal of Agricultural Sciences 2001, Vol. 4(2): 83-88A high yielding, locally adapted cultivar Salama of rice (Oryza sativa L.) which was recommended for cultivation in Tanzania since 1978 was irradiated with gamma rays using two doses (170 & 210 grays) from Cobalt 60 (60C0) in order to shorten the plant height. Twenty three mutant lines in M5 and M6 generations plus two controls were sown in a randomised complete Block Design (RCBD) and replicated three times at the Sokoine University of Agriculture (SUA) farm in Morogoro, Tanzania. The objective of the study was to estimate genetic parameters and the association of various traits with yield. The combined analysis over two years was used to estimate genetic variances heritability and expected genetic gain from selection. The data generated were also used to perform correlation and path coefficient analysis. Analysis of variance revealed significant differences, among the tested genotypes for all the characters tested. Significant genotype X Year interactions were observed for all the characters except number of tillers per plant and 1000 grain weight. High genotype coefficient of variation heritability estimates and expected genetic advance were recorded for plant height number of tillers per plant and 1000 grain weight. Correlation and path coefficient analysis revealed that days to 50% flowering and number of panicles per square metre were important characters that incluenced yiel

Variation and inter-relationship, between yield and, some agronomic characters in induced rice (Oryza sativa L.) mutants

Tanzania Journal of Agricultural Sciences 2001, Vol. 4(2): 83-88A high yielding, locally adapted cultivar Salama of rice (Oryza sativa L.) which was recommended for cultivation in Tanzania since 1978 was irradiated with gamma rays using two doses (170 & 210 grays) from Cobalt 60 (60C0) in order to shorten the plant height. Twenty three mutant lines in M5 and M6 generations plus two controls were sown in a randomised complete Block Design (RCBD) and replicated three times at the Sokoine University of Agriculture (SUA) farm in Morogoro, Tanzania. The objective of the study was to estimate genetic parameters and the association of various traits with yield. The combined analysis over two years was used to estimate genetic variances heritability and expected genetic gain from selection. The data generated were also used to perform correlation and path coefficient analysis. Analysis of variance revealed significant differences, among the tested genotypes for all the characters tested. Significant genotype X Year interactions were observed for all the characters except number of tillers per plant and 1000 grain weight. High genotype coefficient of variation heritability estimates and expected genetic advance were recorded for plant height number of tillers per plant and 1000 grain weight. Correlation and path coefficient analysis revealed that days to 50% flowering and number of panicles per square metre were important characters that incluenced yiel

Performance of early maturing mutants derived from 'supa' rice (Oryza sativa L.) cultivar

Tanzania Journal of Agricultural Sciences 2001, Vol 4(1) : 37-44Supa rice (Oryza saliva L.) cultivar which is very popular in Tanzania was sent for irradiation at the Seibersdorf Laboratory, Vienna, Austria in 1994. The dry seeds were irradiated with gamma rays using three doses (170, 210 and 240Gy) from Cobalt 60 (60CO) in order shorten the plant height and maturity period. From the resulting mutantbpopulations originating from modified single seed descent method, five very early maturing lines plus the original cultivar were evaluated in replicated trials at two sites (SUA and Dakawa) in 1999. The trial was laid in a Randomised Complete Block Design replicated three times. The data generated include plants height, days to 50% flowering, panicle length number of productive tillers per plant, 1000 grain weight, percent filled grains per panicle and grain yield. The mutants and the parent were also screened for grain quality characteristics. The data collected were subjected tp the Analysis of Variance and correlation analysis using MSTAT -C. Path coefficient analysis was also performed to determine the cause - effect relationship. The analyis of variance revealed that there were significant differences between the mutants and their parent for all the characters tested except 1000 grains weight and panicle weight. The mutants flowered up to 24 days earlier than the parent. Further analysis revealed that grain yield was positively correlated with percent filled grains per panicle. Days to 50% flowering and 1000 grain weight exerted negative direct effect on yield. Changes in grain quality were also observed emphasizing the importance of conducting cooking and taste panel tests

Inheritance of resistance to bacterial blight in ten rice (oryza sativa l.) cultivars

Tanzania Journal of Agricultural Sciences 2000, Vol. 3(1) : 39-46Ten rice cultivars from the International Rice Germplasm Centre originating from Bangladesh were analysedfor the~r genetics of resistance to bacterial blight. The test cultivars were selected on the basis of their high level ofresistance to races IV & VI ofXanthomonas oryzae pv. oryzae. The mode ofinheritance was studied by crossing the test cultivars with Taichung Native 1 (TNI) which is highly susceptible to the races 1,2,3;4 & 6 of X. Oryzae pv. oryzae. The genetic analysis revealed that the test cultivars have two recessive genes conferring resistance to races 1 (PX 061) and 6 (PX 079) of X. oryzae pv oryzae, respectively. The allelic relationship of genes conferring resistance with xa-S and xa-13 was studied in progenies derived from crosses between the cultivars and IRBBS and IRBB13 which are near isogenic lines carrying genes xa-S and xa-13 respectively. The Chi-square analysis of F2 populations revealed that resistance ilJ these cultivars to race 1 was conferred by xa-S. Resistance to race 6 was found to be conferred by another gene which was non-allelic to xa-13

Performance of early maturing mutants derived from 'supa' rice (Oryza sativa L.) cultivar

Tanzania Journal of Agricultural Sciences 2001, Vol 4(1) : 37-44Supa rice (Oryza saliva L.) cultivar which is very popular in Tanzania was sent for irradiation at the Seibersdorf Laboratory, Vienna, Austria in 1994. The dry seeds were irradiated with gamma rays using three doses (170, 210 and 240Gy) from Cobalt 60 (60CO) in order shorten the plant height and maturity period. From the resulting mutantbpopulations originating from modified single seed descent method, five very early maturing lines plus the original cultivar were evaluated in replicated trials at two sites (SUA and Dakawa) in 1999. The trial was laid in a Randomised Complete Block Design replicated three times. The data generated include plants height, days to 50% flowering, panicle length number of productive tillers per plant, 1000 grain weight, percent filled grains per panicle and grain yield. The mutants and the parent were also screened for grain quality characteristics. The data collected were subjected tp the Analysis of Variance and correlation analysis using MSTAT -C. Path coefficient analysis was also performed to determine the cause - effect relationship. The analyis of variance revealed that there were significant differences between the mutants and their parent for all the characters tested except 1000 grains weight and panicle weight. The mutants flowered up to 24 days earlier than the parent. Further analysis revealed that grain yield was positively correlated with percent filled grains per panicle. Days to 50% flowering and 1000 grain weight exerted negative direct effect on yield. Changes in grain quality were also observed emphasizing the importance of conducting cooking and taste panel tests

Inheritance of resistance to bacterial blight in ten rice (oryza sativa l.) cultivars

Tanzania Journal of Agricultural Sciences 2000, Vol. 3(1) : 39-46Ten rice cultivars from the International Rice Germplasm Centre originating from Bangladesh were analysedfor the~r genetics of resistance to bacterial blight. The test cultivars were selected on the basis of their high level ofresistance to races IV & VI ofXanthomonas oryzae pv. oryzae. The mode ofinheritance was studied by crossing the test cultivars with Taichung Native 1 (TNI) which is highly susceptible to the races 1,2,3;4 & 6 of X. Oryzae pv. oryzae. The genetic analysis revealed that the test cultivars have two recessive genes conferring resistance to races 1 (PX 061) and 6 (PX 079) of X. oryzae pv oryzae, respectively. The allelic relationship of genes conferring resistance with xa-S and xa-13 was studied in progenies derived from crosses between the cultivars and IRBBS and IRBB13 which are near isogenic lines carrying genes xa-S and xa-13 respectively. The Chi-square analysis of F2 populations revealed that resistance ilJ these cultivars to race 1 was conferred by xa-S. Resistance to race 6 was found to be conferred by another gene which was non-allelic to xa-13

Influence of Genetic and Genotype X Environment Interaction on Quality of Rice Grain

Rice ( Oryza sativa ) grain attributes, including among others milling quality, grain length and shape, amylose content, and aroma are critical in varietal development and subsquent adoption at the farm level. It is, therefore, important to understand the influence of genetic and G x E interaction on these grain attibutes. Thus, experiments were laid out during 1999-2000 at the Tanganyika Agricultural Cooperative, Ifakara (irrigated culture) and at Sokoine University of Agriculture (upland conditions) both in Morogoro region, to obtain relative magnitudes of variety x environment interactions, heritability and genetic advance aspects on physical and biochemical rice grain quality attributes. High significant positive genotypic and phenotypic correlations were revealed between gel consistency (GC) and both the grain length (GL) and amylose content (AC). Gel consistency had high estimates of heritability and expected genetic advance, and is thus a reliable selection criterion for amylose content in early generations of rice improvement. The observed variation among genotypes under different environments suggest that in order to ensure high grain quality, there is need to select genotypes for particular cropping environments.Les attributs de riz ( Oryza sativa ), inclut parmi d'autres la qualité au moulant, la longueur et la forme des grains, le contenu d'amylose, et l'arôme sont importants dans le développement variétal et l'adoption au niveau de ferme. C'est plus important de comprendre l'influence de génétique et l'interaction G x E sur ces attributs de grain. Ainsi, les expériences ont été faites entre 1999-2000 à la Coopérative agricole de Tanganyika, Ifakara (sous culture irrigué) et à l'Université d'Agriculture de Soko¿ne (sur haute terre conditionnée) les deux dans la région de Morogoro, pour obtenir des magnitudes relatives des interactions variété x environnement, héritabilité et les aspects d'avance génétiques sur les attributs de qualité de grain de riz physiques et biochimiques. Les hautes corrélations, significatives et positives entre génotypes et les phénotypes ont été révélées entre l'homogénéité de gel (GC) et la longueur de grain (GL) et le contenu d'amylose (AC). L'homogénéité de gel a eu la haute estimation de héritabilité et l'avance génétique prévue, et est un critère de sélection fiable pour le contenu d'amylose dans toutes les générations d'amélioration de riz. La variation observée parmi les génotypes sous les environnements différents suggère que pour garanti la haute qualité de grains, il y a nécessité de choisir des génotypes particulier pour des environnements différents

A review of maize, rice, tomato and banana research in Tanzania

Tanzania Journal of Agricultural Sciences 2015, Vol. 14(1): 1-20Crop improvement is critical for the sustainable production of crops that contribute to healthy diets, alleviation of hunger and poverty, and enhanced quality of life for people across diverse social economic strata around the world. The development and improvement of crops that can cope with the extreme biotic and abiotic stresses brought about by climate change is probably one of the most important steps that can be taken by any country to ensure a plentiful, healthy, and nutritious food supply for its population. This requires the use of all tools and technologies in the development of new and improved crop cultivars. Maize, rice, and vegetables (tomatoes and bananas) are important crops grown in Tanzania and production has steadily increased for the past 40 years. However, yield per unit area is generally very low, Maize averages 1.4 t/ha while the potential yield is 5 t/ha and rice averages 0.5-2 for upland ecologies and 4.5-6.0 t/ha for irrigated ecologies compared to the potential yield of 5t/ha and 10-11 t/ha respectively. Tomato production is higher than other vegetable crops in Tanzania, with a total annual production of 129,578 t, representing 51% of the total vegetable production. Average tomato yield is from 2.2 to 3.3 t/ha which is far below the world average of 27.5 t/ha. This stands in contrast to overall global production of maize, rice, and tomatoes which averaged 34, 21, and 43%, respectively, over the same time period, mainly through crop improvement programs and the use of new technologies. The innovative Agricultural Research Initiative (iAGRI), is a project that is being implemented within the framework of the US Government’s Global hunger and Food Security Initiative (GHFSI). This study was commissioned by iAGRI to develop a research background paper on crop improvement strategies for maize, rice and selected horticultural crops, the focus crops of Feed the Future project. The information was obtained through review of available literature and consultation with relevant scientists and stakeholders

A review of maize, rice, tomato and banana research in Tanzania

Tanzania Journal of Agricultural Sciences 2015, Vol. 14(1): 1-20Crop improvement is critical for the sustainable production of crops that contribute to healthy diets, alleviation of hunger and poverty, and enhanced quality of life for people across diverse social economic strata around the world. The development and improvement of crops that can cope with the extreme biotic and abiotic stresses brought about by climate change is probably one of the most important steps that can be taken by any country to ensure a plentiful, healthy, and nutritious food supply for its population. This requires the use of all tools and technologies in the development of new and improved crop cultivars. Maize, rice, and vegetables (tomatoes and bananas) are important crops grown in Tanzania and production has steadily increased for the past 40 years. However, yield per unit area is generally very low, Maize averages 1.4 t/ha while the potential yield is 5 t/ha and rice averages 0.5-2 for upland ecologies and 4.5-6.0 t/ha for irrigated ecologies compared to the potential yield of 5t/ha and 10-11 t/ha respectively. Tomato production is higher than other vegetable crops in Tanzania, with a total annual production of 129,578 t, representing 51% of the total vegetable production. Average tomato yield is from 2.2 to 3.3 t/ha which is far below the world average of 27.5 t/ha. This stands in contrast to overall global production of maize, rice, and tomatoes which averaged 34, 21, and 43%, respectively, over the same time period, mainly through crop improvement programs and the use of new technologies. The innovative Agricultural Research Initiative (iAGRI), is a project that is being implemented within the framework of the US Government’s Global hunger and Food Security Initiative (GHFSI). This study was commissioned by iAGRI to develop a research background paper on crop improvement strategies for maize, rice and selected horticultural crops, the focus crops of Feed the Future project. The information was obtained through review of available literature and consultation with relevant scientists and stakeholders