Correlation and path studies in wheat under normal and saline conditions

D. KUMAR, S.C. SHARMA and S.C. GUPTA

Haryana Agricultural University, Regional Research Station BAWAL-123 501 (M. garh), India

Improvement in grain yield is the sole aim of breeding for cereals under any agroclimatic or soil condition. However, yield being the complex out come of its components, selection based on yield alone would be misleading. Selection based on yield components would, therefore, be more rewarding. This requires information on nature and magnitude of variations in the base population, association of yield components with yield and among themselves ; and the extent of environmental influence. Correlation coefficients, though bring out necessary information on nature and extent of various associations yet do not provide information on cause and effect relationship. Path coefficient analysis measures the direct influence of a variable on other and permits the partition of associations into components of direct and indirect influences (DEWEY & LU 1959). Reports on correlation and path coefficient analysis are many in wheat under normal condition. (BAKER et al. 1968 ; JAIMINI et al. 1974 ; KUMAR 1979), information on the same under salt stress conditions in crop plants as a whole (SINGH 1979, 1980) and wheat, in particular (GIRIRAJ et al. 1980) are quite deficient. Present study was, therefore, undertaken to compute correlation and path coefficients in 15 genotypes of wheat under normal and saline environments.

Material and Methods

In the winter season of 1979-80, a field plot study was conducted on sandy loam light textured soils (ECe .5, pH 8.0). Fifteen genetically diversified cultivars common wheat (WL- 711, WH-157, WH-147, UP241, UP270, UP 368, HD2122, HD2160, HD 1593, HD 1982, K 7435, HP 1102, HUW-SDW-1 and K. 68) were field grown in the main plots separated by polythene sheets burried 90 cm deep to check lateral movement of salts. A split-plot design with three repeats was adopted. Levels of water salinity 2.1 (control) and 16.0 mmho/cm were adjusted to main plots whereas, varieties to 2.5 m long single rows in each main plot. Waters of desired salinity were prepared keeping in view the natural poor quality under ground water encountered in this locality which contained Na : Mg : Ca=60 : 25 : 15 and Cl : SO₄ : HCO₃ =2 : 1 : 1 as reported by KUMAR et al. (1981). Source of control water was a tube-well, possessing good quality water. In all 5 irrigations of 6 cm each were applied.

One month of sowing, 50 plants at a distance of 5 cm apart were spaced in each row. Germination of seeds was assessed and expressed as a percentage, whereas, data on number of tillers/plant, plant height (cm), number of grain/spike, 1,000-grain weight (g) and grain yield/plant (g) were recorded on 10 random plants for each treatment. Correlation coefficients were computed at the phenotypic level. The path coefficient analysis of yield/ plant with its five components were estimated following DEWAY & LU (1959).

Results and Discussion

Correlation coefficients: The association of grain yield with plant height and grains/spike was significant positive ; was however, significant negative with germination of seeds under normal conditions (Table 1). These associations signify that yield/plant was adversely affected due to plant density increased, following higher germination rate, high yielding genotyes on the other possessed more grains/spike and were rather tall in stature under normal environment. In saline environment, however, all the attributes excepting 1,000- grain weight possessed significant positive association with grain yield ; associations of plant height and tillers/plant were however highly significant. This underlines the importance of plant height and tillering ability in selecting high yielding genotypes of wheat under salt stress environment. These results corroborate the earlier findings of TORRES & BINGHAM (1973) on tillers ; and of GIRIRAJ et al. (1980) and KUMAR et al. (1981) on plant height that tillers and plant height are the seriously affected components under saline conditions in wheat.