Volume 9, No. 5, 2020

Comparative Study of Germinative and Recovery Behavior of Two Species of Atriplex (Atriplex canescens (Pursh) Nutt and Atriplex halimus L.) under Salt Stress
A Aissat, A Achour, L Maachou and M Belkhodja
Int J Agri Biosci, 2020, 9(5): 203-208.
Abstract
Abstract

This work is a comparative study of germination under salt stress conditions on two halophilic species of the Amaranthaceae family; Atriplex canescens (Pursh) Nutt and Atriplex halimus L. Seeds were treated with NaCl at 600- and 900-mM concentrations and stored in an oven at 25°C for 10 days. Observations focused mainly on the germination capacity, the velocity coefficient, the latency, the average germination time and the length of the seedlings. After the reversibility test, we recovered the seeds not germinated under saline stress in order to submit them to an environment without NaCl. Results show that increasing the NaCl concentration reduces significantly the germination capacity of the seeds. Without NaCl, the final germination rate of the seeds of Atriplex canescens (Pursh) Nutt and Atriplex halimus L. varies from 100 to 95% respectively; while this rate drops with salinity for the seeds of Atriplex canescens (Purch) Nutt and becomes zero for Atriplex halimus L. The capacity and the average speed of germination decrease as the salinity increases. In addition, salinity negatively influences the emergence of the vegetative system of the two species of Atriplex. Regarding the reversibility test, the results show that the two species of Atriplex are affected by osmotic and toxic depressions.

Keywords: Atriplex canescens (Pursh) Nutt; Atriplex halimus L.; germination; halophyte; NaCl; reversibility; stress.

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The Role of Genotype by Environmental Interaction in Plant Breeding
Temesgen Begna
Int J Agri Biosci, 2020, 9(5): 209-215.
Abstract
Abstract

A genotype x environment interaction is a change in the relative performance of a character of two or more genotypes measured into two or more environments. Living organisms are made up of genes whose expressions are subject to modification by environment; therefore, genotypic expression of a phenotype is environmentally dependent. This is because genotypes exhibit different level of phenotypic expression under different environmental conditions resulting in cross over performances. In genotype x environment interaction, the magnitude of the observed genetic variation changes from one environment to another and tends to be larger in better environments than poor environments. Genotype x environment interaction is a fundamental component in understanding complex trait variation and the most challenging factor in identification of genetic variation. Interaction involves a change in rank order for genotypes between environments and the relative magnitude of genetic, environmental and phenotypic variance between environments. Genotype x environmental interaction can lead to differences in performance of genotypes over environments. The relationship between selection environments and target production environment had been a major problem because many of the selected activities performed by the conventional approach. Genotype x environment interaction analysis can be used to analyze the stability of genotypes and the value of test locations. Genotypes by environment interactions are almost unanimously considered to be among the major factors limiting response to selection and, in general, the efficiency of breeding programs. Exploitation of genetic variability is the most important tool in plant breeding and this has to be inferred by phenotypic expression. The consequences of the phenotypic variation depend largely on the environment. This variation is further complicated by the fact that not all genotypes react in similar ways to change in environment and no two environments are exactly the same. If relative performance of genotypes grown in different environments is different, then genotype x environment interaction becomes a major challenging factor to crop breeding programs. Genotype x environment interaction is one of the main challenges in the selection of broad adaptation and stable genotypes in most breeding programs. The varietal stability could be challenged not only due to the change in the test environment but also due to change in growing season per environment. Some environmental variations are predictable (soil type, soil fertility, plant density) whereas others also may be unpredictable (rainfall, temperature, humidity). Generally, genotype x environment interaction is the most critical in plant breeding to make selection of genotypes based on their adaptability and stability for desirable traits.

Keywords: Genotype x Environmental Interaction; Environment; Phenotype; Genotype; Interaction; Variation.

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