Effect of salinity on growth and leaf area of sunflower ( Helianthus annuus L . ) cv . suntech-85

A pot experiment was conducted during 2009 to 2010 to access adverse effect of salinity on growth of sunflower (Helianthus annuus L.) cv. Suntech 85. The result revealed that with increasing salinity concentration, the growth parameters declined except at lower salinity level 5 E.C. which does not show any adverse effect rather, there was slight increase in all growth parameters as compared to control. Whereas, higher salinity level with 25 E.C. was deleterious and showed a decrease of 20.96, 39.92 and 22.44% in shoot length, 35.93, 33.33 and 31.50% in root length, 56.46, 29.95 and 28.81% in shoot fresh weight, 42.42, 51.28 and 34.73% in root fresh weight, 30.26, 45.54 and 27.08% in shoot dry weight, 63.41, 55.00 and 57.29% in root dry weight and 44.82, 42.30 and 38.14% in leaf number and 41.56, 33.04 and 40.00% in leaf area as compared to control at 30, 60 and 90 DAS respectively. This decrease in growth at higher salinity levels might be due to the toxic effects of salinity, which badly affected plant physiological aspects such as osmotic adjustment and ion accumulation creating drought-like conditions for the plant.


INTRODUCTION
Saline and sodic soils occur naturally in arid and semiarid climate conditions and is a major problem in crop production (Szaboles, 1994).It is estimated that one third of the irrigated land in the world is affected by high salinity (Mass and Hoffmann, 1976).About ten million-hectare lands are affected by high salinity and sodicity in India alone.Moreover, Uttar Pradesh had about 1.28 million hectare area under saline-alkali soils of which 4,000 to 20,000 ha land occurs in Shahjahanpur district of Uttar Pradesh (Srivastava et al., 2002).
Salinity limits the crop production and yield.Plants growing in saline atmosphere suffer some degree of water and salt stress, which affects every aspect of plant growth and development, as all the phases of plant growth from germination to maturity are affected by the environment in which the plant grows (Boyer 1982;Kumar et al., 2007).
When it comes to the production of oil seed crops, salinity plays a limiting factor in their production; oil crops occupy a prime importance in Indian economy (Sharma, 2003).The maximum oil production in India during 2003 to 2004 was 25.1 million tons, which was 14 million ton less than self dependency in oil production.In India per day availability of vegetable oil per person is 12 g which should be 18 g per person according to F. A. O report (Hedge, 2004).In the present study an attempt has been made to observe the effect of different salinity concentrations on growth parameters of sunflower (Helianthus annuus L.) cv Suntech -85.

MATERIALS AND METHODS
The experiment was conducted at Department of Botany, G. F. (P.G.) College Shahjahanpur, Uttar Pradesh, India, on sunflower (H.annuus L.) cv.Suntech -85.The experiment was set in 9 inches earthen pots in factorial randomized manner containing a mixture of garden soil, humus and sand in a ratio of 2:1:1 in a net house.
Artificially prepared different grades of salinity concentrations viz, 0, 5, 10, 15, 20 and 25 electrical conductivity (E.C.) were prepared by mixing salts of sodium chloride, calcium chloride and sodium sulphate in a ratio of 7:2:1 and were applied to pots periodically.Analysis was done by uprooting the plants carefully and washed thoroughly under running tap water, the shoot and root lengths were taken with the help of meter scale.The fresh weight of shoot and root was taken on single pan balance, and for the dry weight of shoot and root the plants were kept in an hot air oven at 60°C and after seven days the dry weight was taken on single pan balance.
The leaf number was calculated by counting number of leaves per plant and the total leaf area of plant was determined with the help of Kemp's constant method.

RESULTS
The results presented in Tables 1 and 2 showed that with the increasing concentrations of salinity there was gradual decline in shoot and root length but there was slight increase of 1.

DISCUSSION
It is an established fact that salinity inhibits plant growth.Generally plants growing in saline atmosphere face water deficit as similar to the drought stress.The water potential of plants growing in saline soil became low due to increasing concentration of salts in root zone (Munns and Termaat, 1986).Excessive amount of salt in root zone affects growth of root, photosynthesis, enzyme activation and nutrient uptake and ultimately decreasing plant growth (Delane et al., 1982).Results from the above study indicate that H. annuus cv.Suntech-85 is a moderate salt tolerant species during growth and can withstand the salinity level upto 5 E. C. conentration.Infact all the growth parameters show a little enhancement (Tables 1 to 5 and Graphs I to VIII) over the control in 5 E. C. treatment.Generally, the halophytes show a stimulation of growth at this concentration which is otherwise inhibitory to the growth of glycophytes.However, Salinity level higher than 5 E. C. level decreased all the growth parameters in this study as reported by several workers in other oil crops groundnut (Mensah et al., 2006), cotton (Maiti et al., 2006), mustard (Sadiq et al., 2002;Kumar et al., 2005Kumar et al., , 2007)), soybean (Shereen et al., 2001) and safflower (Kaya and Ipex, 2003).Similar results have also been reported in Leaf area which is a good indicator of water and salinity stress, since leaf expansion generally requires a high turgor pressure for cell enlargement directly affecting photosynthetic rate and growth (Huang and Redmann, 1995).
Effect of salinity on Shoot length of Sunflower cv Suntech -85 after 30, 60 and 90 DAS. on Root length of sunflower after 30,60 and 90 DAS 30 DAS 60 DAS 90 DAS Percentage increase/decrease in root length Graph II.Effect of salinity on Root length of Sunflower cv Suntech -85 after 30, 60 and 90 DAS.Percentage increase/decrease in shoot fresh Graph III.Effect of salinity on shoot fresh weight of Sunflower cv Suntech -85 after 30, 60 and 90 DAS.Effect of salinity on root fresh weight of Sunflower cv Suntech -85 after 30, 60 and 90 DAS.Percentage increase/decrease in shoot dry weight Graph V. Effect of salinity on Shoot dry weight of Sunflower cv Suntech -85 after 30, 60 and 90 DAS.

Table 1 .
Effect of salinity on shoots and roots length in Helianthus annuus L. cv.Suntech-85 at 30, 60 and 90 days after sowing (DAS) stages.

Table 2 .
Effect of salinity on fresh weights of shoots and roots in Helianthus annuus L. cv.Suntech-85 at 30, 60 and 90 days after sowing (DAS) stages.
N. B. = Each value is a mean of three replicates, E. C. = Electric conductivity, D. A. S. = Days After Sowing.

Table 3 .
Effect of salinity on dry weights of shoots and roots in Helianthus annuus L. cv.Suntech-85 at 30, 60 and 90 days after sowing (DAS) stages.

Table 4 .
Effect of salinity on leaf number in Helianthus annuus L. cv.Suntech-85 at 30, 60 and 90 days after sowing stages.
N. B. = Each value is a mean of three replicates, E. C. = Electric conductivity, D. A. S. = Days After Sowing.