| Salt tolerance of wheat in relation to nature of salinity
R.P.S. CHAUHAN and J. PRASAD Department of Agricultural Chemistry, R.B.S. College, Bichpuri, Agra, India-283105 Wheat is one of the important cereal crops of the world which is reported to be grown successfully upto an ECe level as high as 6.00 and 6.5-7.5 mmhos/cm by MASS et al. (1977) and CHAUHAN et al. (1980) respectively. So far salt-tolerance of wheat has been evaluated as its non-specific response to decreased water potential caused by excessive amount of salts in the root medium. Salt-tolerance of crops varies with the nature of the salt constituting salinity to which wheat may not be an exception. A study was, therefore, undertaken to find out the effect of type of salinity on wheat (Triticum aestivum Linn. emend. Thell) grown on alkaline sandy loam soils under semi-arid climatic conditions of India. Materials and Methods Pot experiments were conducted in 1980-81 in R.B.S. College, Bichpuri, Agra. Seven sets of experiments were conducted with NaCl, CaCl2, MgCl2, NaHCO3, Na2SO4, NaCl+Na2 SO4+NaHCO3 (1 : 1 : 1) and NaCl+MgCl2+CaCl2 (1 : 1 : 1) each at two levels of salinity, viz 7.5 and 15.0, 7 and 11.5, 7.0 and 11.5, 6 and 12.0, 6 and 11.5, 7.0 and 11.2 and 7.5 and 11.5 mmhos/cm ECe respectively excluding a common control. The soil used had ECe 3 mmhos/cm, pH 8.2, organic carbon 0.32% and 9.6, 3.4, 16.0, 16.1 and 12.6 me/l Ca2+, Mg2+, Na+, Cl- and SO42 respectively were present in saturation extract with 6.3 sodium adsorption ratio. The experiments were conducted in china-clay cylindrical pots, having a diameter of 30 cm and capacity of 10 kg, arranged in a randomized block design, with 3 replications. Each pot was filled with 10 kg soil, and recommended amounts of N, P and K were mixed in each pot before sowing. In each pot 10 seeds of wheat (WL 711) were sown on 28 November, 1980. After emergence, seedlings were thinned 6 to a pot. The crop was raised with standard management practices and irrigated six times each with 2 litres of good quality canal water. Grain and plant samples at flowering stage collected from each pot, were mixed treatmentwise and anlysed for Ca, Mg, Na, K, P, and protein in case of grain and for former four in case of plant samples following usual laboratory procedures. Free proline was determined in fresh leaves according to the method described by BATES et al. (1973). Results and Discussion Effect of nature of salinity on germination, 100 grain weight, free proline accumulation and yield of wheat, have been presented in Table 1. The germination was delayed with salinity in general. The maximum delay at first level of salinity was observed with the salinity caused by the mixture of sodium salts. At second level of salinity, germination delayed by a range of 0-2.5 days depending upon the nature of salt except NaCl where salinity was too high. 100 grain weight decreased significantly with NaCl and NaHCO3 salts even at first level of salinity ; tolerance limit of wheat, over control while in other cases reduction was noted at highest levels of salinity. The decline in 100 grain weight may be attributed to decreased photosynthesis and poor utilization of photosynthate in presence of high osmotic pressure in the root zone along with the disturbed inorganic nutrition of plants (KHALIL et al. 1967). |
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