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Results and discussion

During wheat crop production, the salinity build up (ECe) has been recorded about 1.0 to 1.5 times to that of irrigation water (ECiw). This increased ECe ultimately increased the soil osmotic potential, resulting reduced water intake by crop besides specific ion effect. Plants make adjustment when faced unfavourable conditions upto certain limit but beyond it, depressed plant growth happened.

The data pertaining to effect of varying saline irrigation on wheat crop growth and yield for seven years of experimentation are presented in Table 2 and Table 3. The germination performance of seed, which directly related to soil moisture content, revealed that it decreased progressively with salinity of water. However, the magnitude of reduction was more with high salinity. From ECiw-6 to 8 dS/m it decreased about 1.2% with each unit of ECiw and from ECiw-8 to 10 dS/m the reduction per unit ECiw was about 4%. The correlation between ECiw and germinability (r = -0.61) was also found negative and significant with regression equation as Y = -1.82 x + 65.62.

The crop growth judged by plant height and number of tillers revealed that both these characters declined with salinity but only beyond ECiw-8 dS/m. The ECiw12 declined crop growth by about 10% while at ECiw16 by about 30%. The correlation between ECiw vs plant height (r = -0.36) and number of tillers (r = -0.37) were found negative and significant. The respective regression equations are Y = -1.25 x + 87.5 and Y = -1.08 x + 69.4.

The yield contributing character viz. ear length, number of grain per ear and 1000 grain weight were also studied. It has been observed that upto ECiw12 dS/m ear length was not found affected and with 3.6% reduction only at ECiw16 dS/m. Similarly, number of grain per ear was not found to be affected upto ECiw8 and only with 5% reduction at ECiw12 to 16 dS/m. 1000 grain weight was started to declined from ECiw2 dS/m onwards progressively but with very low degree (Table 2). The correlation between ECiw and these yield attributes was rated non-significant (Table 3).

The crop yield was found to decline with salinity of irrigation water. The drymatter yield declined only at ECiw12 and 16 dS/m by 18 and 33% respectively. The remarkable reduction in , grain yield started above ECiw8 dS/m. With ECiw12 and 16 dS/m the grain yield lowered by 21 and 37% respectively. Reduction in grain yield per unit EC of water from 8 to 16 dS/m was about 4%. Almost similar reduction in wheat yield was reported by Poonia et al. (1974) and Tripathi and Pal (1979). Mildy saline water (ECiw2 to 5 dS/m) have shown the improvement in grain and drymatter yield (Tripathi et al. 1971). The ECiw has been found to be significantly negative correlated with grain yield (r = -0.50) and drymatter yield (r = -0.42) with respective regression equation as Y = -1.01 x + 43.49 and Y = -2.09 x +103.02.

Further, the relationship of different plant characters with grain yield under saline irrigations were also assessed and presented in Table 4. The figure No.1 shows that germination performance is closely related with grain yield. Plant height and number of tillers also showed the trend similar to yield. The ear length and number of grain per car had shown no resemblance with grain yield pattern. The correlation studies (Table 4) also showed that only germination, number of tillers and plant height were found to be significantly correlated with grain yield.

 Thus, in light textured soils and semi arid climatic conditions, wheat can be grown upto ECiw-8 dS/m comparable to control (canal water). The saline irrigation at ECiw-12 and 16 dS/m reduced wheat yield by 21 and 37 per cent over control with negative significant correlation (r = -0.42). The reduction in yield mainly caused by poor germination and tillering, stunted growth and to some extent by low 1000 grain weight.

Acknowledgement

The authors are very much thank to I.C.A.R. New Delhi for financial assistance, Principal, Raja Balwant Singh College, Agra for providing necessary facilities and to the staff who made this investigation a success.


References

Bernstein L (1964) Salt Tolerance of Plants. pp.10-15 Information Bulletin 283, United States Department of Agriculture Washington.

Bhumbla DR, Kanwar JS, Mahajan KK and Bhajan Singh (1964) Effect of irrigation waters of different sodium and salinity hazards on the growth of the crops and the properties of soils, proceedings of General Symposium on the problems of Indian Arid Zone Research Institute, Jodhpur.

Kanwar JS and Kanwar BS (1969) Quality of irrigation waters. Trans. 9th Int Congr Soil Sci 1: 391-403.

Poonia SR, Johorar LR, Nath J and Khanna SS (1974) Effect of quality of irrigation water, leaching levels and farm yard manure on the performance of wheat and pearl millet. Indian J Agric Sci 44: 854-859.

Tripathi BR, Misra B, Singh RM and Singh BP (1971) Quality of irrigation water and its effect on soil characteristics in semi-desert tract of Uttar Pradesh. II Effect of water quality on soil properties and yield of wheat crop. Indian J Agron 16: 95-102.

Tripathi BR and Pal B (1979) Seasonal salt accumulation and salt tolerance of wheat to saline water in the semi-desert of Uttar Pradesh. Indian J Agric Sci 49: 206-210.

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