Ideotype Research Articles

Evaluation of intra and interspecific rice varieties adapted to valley bottom conditions in Burkina Faso

Rice is one of the major staple foods in Burkina Faso and in-country production covers about 60% of the demand and 40% is met from imports. The immense potential of the lowlands in Burkina Faso for durable intensification of rice cropping have not been realised due to biotic and abiotic constraints. Hence, there is an urgent need to increase and improve the production of rice in order to meet up with the high demand. To meet the demand, the rice research program in Burkina Faso evaluated intra and interspecific lowland progenies in 2002 and 2003. The aim of the study is to introduce new lowland NERICAs through a participatory approach and to identify ideotypes that are adapted to lowland conditions. Variations did exist among the 16 rice varieties with respect to the 9 variables that were evaluated. A principal components plot and clustering analysis technique were used to group the accessions. The interspecific varieties formed the most interesting group and have a better capacity for adaptation to the diversity of lowlands. They have acceptable yields, sometimes higher than those of intraspecific varieties and check. Thus, the results obtained were quite encouraging and showed that, the varieties possess good agronomic traits that are well adapted to intensify lowland rice farming. The recent naming of some of these interspecific varieties as NERICA-L (New Rice for Africa Lowland) by AfricaRice Center has confirmed that they compare well with the traditional varieties. Thus from this study, we now have a new set of interspecific lines that are adapted to lowland conditions that can be tested to meet farmers’ needs. Key words: Oryza glaberrima, Oryza sativa, hybridisation, inter-specific, NERICA, sterility, yields.

Evaluation of intra- and inter-specific rice varieties adapted to valley fringe conditions in Burkina Faso

The immense potential of the lowlands in Burkina Faso for durable intensification of rice cropping have not been realised due to biotic and abiotic stress constraints.To this end, the rice research program in Burkina Faso evaluated 16 intra-and inter-specific lowland progenies in 2002 and 2003. The aim of the study is to introduce new lowland NERICAs through a participatory approach and to identify ideotypes that are adapted to lowland conditions. Variability was found among the 16 rice varieties with respect to the 9 variables that were evaluated. A principal components plot and clustering analysis technique were used to group 16 intra-and inter-specific lowland progenies. The inter-specific varieties formed the most interesting group and showed a better capacity for adaptation to the diversity of lowlands. They had good yields, sometimes higher than those of intra-specific varieties and check. Thus, the results obtained were quite satisfactory as the varieties possess good agronomic traits that are well adapted to intensified lowland rice farming. The recent naming of some of these inter-specific varieties as NERICA-L (New Rice for Africa Lowland) by Africa Rice Center confirmed their status. Thus from this study, a new set of inter-specific lines that are adapted to lowland conditions and which the national research programs in Burkina Faso can use in various tests for satisfying farmers’ needs are discussed. Key words: Hybridisation, inter-specific, insect, blast, NERICA, Oryza glaberrima, Oryza sativa, sterility, yield.

Impacts du changement climatique sur la croissance et le développement du blé en France

1 Pole Valorisations de l’Ecophysiologie, ARVALIS – Institut du vegetal, domaine INRA-GEVES, La Miniere, 78280 Guyancourt, France 2 EARL Rouillot Abstract: Knowledge acquired over the paste decades on wheat physiology allows for an estimation of the impacts of key climatic factors on wheat physiology, yield components, as well as a quantification of the main climatic risks for the crop. Using historical weather data sets starting in 1955 from a large number of weather stations, we have concluded that a certain number of climatic risks have changed through comparison of two sequences: 1955-1980 and 1981-2005. Despite a significant anticipation of phenological stages, number of grains per m has been significantly affected by an incresase in water stress during stem extension; also, kernel weight is more strongly penalized through the joint effects of increased drought and especially increased heat stress during grain filling. These tendancies vary geographically. Certain regions have been affected early on (mediteranean region), whereas others are almost untouched as yet (western maritime front). Studies using projected future weather data validates this tendancy and allows its extrapolation. We propose adaptation pathways through escape based on varietal earliness and identify new phenological ideotypes and modes of growth better adapted to future risk. As a complement, the interest of selecting for cultivars tolerant to abiotic stresses is put forward, especially cultivars efficient with regards to water use and resistant to high temperatures. For these aspects, simple diagnostic methods and characterization tools are given. Finally, a preliminary analysis of the adaptation of cropping practices (sowing, nitrogen fertilization, lodging control) is initiated.

THE SEGREGATION OF TREE HABIT ON PEAR SEEDLINGS IN SIX HYBRID COMBINATIONS

Trees habit is an important trait in pear breeding and pear culture (1, 2, 3). The segregation for trees habit of F1 pear hybrids belonging from six combinations was analysed. The seedlings originate in incomplete diallel cross, effectuated with four genitors (Comtesse de Paris, Milenium, Virgiliu Hibernal, Cluj 89-1-81 selection), were framed in six classes of growth (after UPOV Guidelines), respectively architectural ideotype: 1. Fastigiate; 2. Upright; 3. Semi-upright; 4. Spreading; 5. Drooping; 6. Weeping. In each combination, the majority of F1 hybrids had spreading habit (between 57% in Comtesse de Paris x Milenium and 81% in Milenium x Cluj 89-1-81). The occurrence of high percentages of spreading habit seedlings in all combinations (see the table) suggests that this ideotype of tree growth is easy to obtain in pear breeding. Because a valuable type of tree habit for modern plantation is with a spurred growth habit and strong apical control, it can be appreciated that Milenium (a relative new cultivar created at Fruit Research Station Cluj-Napoca) can be used as genitor for this trait. Especially used as mother genitor in cross with Virgiliu Hibernal (another new cultivar obtained at FRS Cluj), Milenium gave birth to the highest percentage of upright seedlings (16%), and with fastigiate habit (3%)

GCA AND SCA EFFECTS FOR RAMIFICATION CAPACITY OF TREES IN F1 APPLE SEEDLINGS

The number of branches per tree was analysed on F1 individuals originated in several crosses between apple cultivars with different architectural ideotypes: spur (Starkrimson, Golden spur), semispur (Liberty), weeping (Florina). The number of branches per tree in F1 hybrid apple, in their third year of vegetation, was different in six combinations, depending on the genotype of genitors, respectively on their architectural ideotype. There have been noticed significant differences among the tested cultivars used as genitors, the average of trait on hybrid combination being comprised between 4.28 in Goldenspur x Liberty and 7.14 in Starkrimson x Florina. A small number of branches per seedling were registered in Starkrimson x Goldenspur combination (4.32), where the both genitors are spur ideotypes. The variability of analysed characters was high, with s% between 33.9 at Liberty x Florina and 56.8 at Starkrimson x Liberty. These values suggest that seedlings with very different number of branches are likely to be identified in each combination. The analysis of variance for GCA and SCA has emphasised the fact that, in the studied apple combinations, both effects of general and specific combining ability contributed to the phenotypic expression of number of branches per tree. Goldenspur showed negative value for GCA, thus this could produce descendents with low vigour and number of branches, if they are used as genitors in apple breeding. Based on the values of general combining ability (GCA) and specific combining ability (SCA) selection of genitors can be very efficient for desirable characters of growth in apple breeding.

Architectural ideotype of pear seedling in five hybrid combinations

The architectural ideotype - type of growing - was studied in a topcross experiment with five hybrid combinations in which Cluj 72-2-100 selection, typical spur, was used as a maternal tester. The analyzed seedlings were at the end of their sixth year of vegetation. There were no significant differences among the five hybrid combinations concerning the distributions of F1 seedling in the four accepted ideotypes (columnar, spur, standard, and weeping). A high variability was found for ideotype (between 18.8% in Cluj 72-2-100 x Napoca and 34.4% in Cluj 72-2-100 x Red Bartlett). The participation rate of genotype in the phenotypic manifestation of this character is relatively low. The coefficient of heritability in broad sense was 0.29 and the coefficient of heritability in narrow sense was very low, 0.001.

Conclusions: Ideotypes and physiology: Tailoring plants for increased production

Conclusions: Ideotypes and physiology: Tailoring plants for increased production

Preface: Ideotypes and physiology: tailoring plants for increased production

Preface: Ideotypes and physiology: tailoring plants for increased production