| Wheat cultivation under saline irrigations
C.P.S.CHAUHAN and S.P. SlNGH I.C.A.R., R.B.S. College, Bichpuri, Agra, India Wheat (Triticum aestivum Linn. emend. Thell) is one of the most important cereal crop of the world, grown in wide range of climatic zone and mostly in irrigated conditions, to nourish the mankind. In the arid and semi-arid areas, saline ground water is a common feature, irrigation with saline water to fulfil the evaporation demand throughout the growth period of crops resulted in soil salinization in the root zone caused deterimental affect on growth and yield potential of the crops. BERNSTEIN (1964), BHUMBLA et al. (1964), KANWAR & KANWAR (1969), TRIPAAHI & PAL (1979) have reported the reduction in yield of wheat with high saline irrigations. Compared to grain yield, the crop growth and yield attributes were found to vary with tolerance/sensitivity for salinity. Therefore, it will be of vital interest for scientist trying to overcome the salinity menace, to predict the wheat crop growth, development and yield potential with varying salinity of irrigation water on the basis of long term experimentation. Materials and Methods A field experiment in microplot of 2.5 x 2.5 m size (net plot size 2 x 2 m) was conducted during rabi seasons of 1972-73 to 1978-79 consequtively at the Research Farm, Raja Balwant Singh College, Bichpuri, Agra, India. The plots were separated by polythene sheets upto 90 cm depth to prevent lateral movement of water. The annual rainfall in the region is about 600-700 mm of which about 80% is received during July, August, September months. The soil was alluvial, sandy loam (16% clay, 14% silt and 70% sand) in texture with 1.75 cm/hr hydraulic conductivity. The soil initially had EC 3 ds/m, pH 8.6, SAR 15 and ESP 6 at surface (0-15 cm) depth. Seven salinity levels of irrigation water with EC 0.6 (control), 2, 4, 6, 8, 12 and 16 ds/m were tried in Randomized Block Design with four replications. Artificially synthetic water were prepared from canal water by adding the salts of chlorides of sodium, calcium and magnesium, and sulfates and bicarbonates of sodium keeping the ratio of Na: Mg: Ca as 60:25:15 and Cl:SO4:HCO3 as 2:1:1 as long as sulfates did not exceed 30 me/l and HCO3 10 me/l and excess of these ions were substituted by chloride ion. The composition of these irrigation water are as per composition of the ground water of this locality. Under the Pearl Millet- Wheat crop rotation for consequitive 7 years on the same field, wheat (HD 1593) was sown in November and harvested in April in respective years. The crop was fertilized with the dose 120 kg/h/N and 60 kg/ha/P2O5. Irrigation was adjusted at 6 cm CPE with 1.0 ratio of CPE/depth of irrigation. In all 4 - 5 irrigations were provided each year for wheat cultivation. The details of rainfall and water table depth are presented in Table 1. Results and Discussion The saline irrigation resulted in soil salinization and under wheat crop production the salinity build up (ECe) has been recorded about 1 to 1.5 times to that of irrigation water (ECiw). This increased ECe ultimately increased the osmotic potential, resulted mainly reduced water intake by crop mainly besides specific ion effect. Plants make adjustment when faced unfavourable conditions upto certain limit beyond that depressed plant growth resulted. The data pertaining to effect of varying saline irrigations on wheat crop growth and yield for 7 years of experimentation are presented in Table 2 and 3. The germination performance, which is directly related to soil moisture content, of seed revealed that it decreased progressively with salinity of water, however, the magnitude of reduction was more with high salinity. From EC 6 to 8 it decreased about 1.2% with each unit of EC and from 8 to 16 the reduction per unit EC was about 4%. The correlation between ECiw and germination (r = -0.61) was also found significant with regression equation as Y = -1.8X + 65.62. The crop growth judged by plant height and number of tillers revealed that both these characters declined with salinity but only beyond EC 8 ds/m. The EC 12 declined crop growth about 10% while at EC 16 it was about 30%. The correlation between ECiw vs plant height (r = -0.36) and number of tillers (r = -0.37) were also found significant. The respective regression equation are Y = -1.25X + 87.5 and Y = -1 .08X + 69.4. |
| --> Next |