Selection of promising genotypes based on path and cluster analyses

Abstract

SU MMARYThe objective of the present paper was to propose a statistical approach to support selection of the most promising genotypes in a breeding programme. The approach is based on applying two state-of-the-art statistical methodologies, likelihood-based path analysis and model-based cluster analysis. The first method is applied to find a causal mechanism lying behind a biological process of development of final crop yield. These results are then used for weighting traits to be used in cluster analysis, which helps select genotypes possessing a desirable level of yield and yield-contributing traits. An application of the approach is presented for a 2-year study on 22 grasspea genotypes, two cultivars (Derek and Krab) and 20 mutants from those cultivars. Seed yield/plant and seven yield-related traits were studied. Among these, plant height, number of branches/plant, pod length and number of seeds/plant determined seed yield ; number of pods/plant influenced seed yield only for 2002. These results were used for appropriate weighting in cluster analysis, which indicated that cultivar Krab and its two mutants, K3 and K64, had the best level of the traits and were the most stable genotypes.

Morphological characteristics of some accessions of grass pea (Lathyrus sativus L.) grown in Europe and nutritional traits of their seeds

“…The earlier studies conducted with grass pea in Poland indicated that a normal rainfall level recorded during a year assures a plant height above 80 cm (Rybiński 2003). In 2002 at the 516 mm precipitation level, the grass pea mutant height was found within 67.8-94.3 cm but in 2003, a particularly dry period (331 mm), plant height ranged from 25.6 to 42.7 cm (Kozak et al 2008). Relatively low plant height and uniform maturity of plants observed in the present research was associated with a strong abiotic stress caused by the long-term drought.…”

Variability of phenotypic and morphological characteristics of some Lathyrus sativus L. and Lathyrus cicera L. accessions and nutritional traits of their seeds

“…The previous studies on grass pea in Poland indicated that at normal annual rainfall amount about 600 mm (Dmochowska 2011), the plant height can be over 80 cm (Rybiński 2003). In 2002, at 516 mm rainfall level, plant height of grass pea mutants ranged from 67.8 up to 94.3 cm but in 2003, exceptionally dry (331 mm), it oscillated between 25.6 and 42.7 cm (Kozak et al 2008). Relatively low plant height (from 37.2 to 63.6 cm) and uniform maturity of plants were observed in the experiment in 2006 and associated with strong abiotic stress caused by long term drought (Grela et al 2010).…”

Use of the correlation coefficient in agricultural sciences: problems, pitfalls and how to deal with them

“…Path analysis has been very popular in various fields, agriculture not being an exception (e.g., Lakshmi andPadma 2011, Maleki et al 2011). More recently path analysis is considered a part of a more general method, structural equation modeling (Shipley 2002), with a new estimation methodology and more application possibilities; applications of such approach to path analysis are also becoming more and more popular in the agricultural sciences (e.g., Dhungana et al 2007, Kozak et al 2008. It is worth mentioning that criticism of path analysis is practically as old as the method itself (Niles 1923), and does not seem to stop.…”