Salt-Tolerance of Tissue-Cultured Date Palm Cultivars under Controlled Environment

A study was conducted in greenhouse environment to determine the response of five tissue-cultured date palm cultivars, AlAhamad, Nabusaif, Barhee, Khalas, and Kasab to irrigation water salinity of 1.6, 5, 10, or 20 dS/ m. The salinity level of 1.6dS/m, was used as a control. The effects of high salinity on plant survival were manifested at 360 days after planting (DAP) onwards. Three cultivars, Khalas, Kasab and Barhee were able to tolerate 10 dS/m salinity level at 24 months after the start of study. Khalas tolerated the highest salinity level of 20 dS/ m and 'Nabusaif' was found to be the least tolerant cv. The average heights of palms and the number of fronds were decreased with increasing salinity levels as time progressed. Keywords—Acclimatization, Irrigation water salinity, Kuwait, Land degradation. I.INTRODUCTION RRIGATION induced salinization of arable land is a wide spread problem in Kuwait. High salt contents in the soil and irrigation water limits plant growth and lead to degradation of soil. Several studies have been conducted to determine the effects of high soil salinity on growth and productivity in date palm [1], [2], [3], [4]. However, under Kuwait’s climatic conditions, plants are exposed to multiple stress conditions such as salt spray, extreme temperatures, low relative humidity, strong winds, and high evaporation rates at the same time. All these factors accelerate the buildup of salt in the soil. The study reported here was conducted to understand the response of five leading date palm varieties to saline irrigation water under greenhouse conditions. II. MATERIALS AND METHODS The study was conducted in the greenhouse at KISR using one year old five cultivars of tissue-cultured date palm, namely, AlAhamad, Nabusaif, Barhee, Khalas, and Kasab. Young palms were procured and acclimatized prior to their use in the study. Fifteen-gallon polyethylene containers filled with agricultural soil and planted with one acclimatized tissue-cultured date palm were used in this experiment. Plants were allowed to fully establish in these containers for two months before subjecting them to salinity treatments. Salinized nutrient solutions @ 1.6, 5, 10, or 20 dS/ m salinity were used for irrigation. Soil from the containers was analyzed for pH and other chemical properties prior to the experiment and at 180 and at 720 days after planting L. Al-Mulla, N. R. Bhat, M. Khalil are with the Kuwait Institute for Scientific Research P. O. Box 24885, 13109 Safat, Kuwait (e-mail: [email protected]). (DAP). The experiment consisted of four salinity levels, five cvs. and three replications (5 plants / replication). With fifteen plants in each experimental treatment and 60 plants under each cultivar, a total of 300 plants were used in this study. Treatments were arranged in a completely randomized block design (CRBD), and recommended cultural and plant protection practices for aphids and mites were followed in growing these plants. III.RESULTS A. Chemical Properties of Soil A representative soil sample was analyzed at the initiation of this study (Table I) for various chemical parameters. The soil samples where the experimental palms were planted were further analyzed after 180 and at 720days of planting to understand the effect of various treatments on salt buildup and nutrient status of the soil (Table II and III). There were corresponding increases in soil salinity at the end of 720 DAP. Continuous irrigation with saline water only slightly increased the pH, but significantly increased the EC of the soil from 2.08 dS/m at time zero (Table I) to 72.4 dS/ m at 720 DAP. Similarly, the levels of Ca, Mg, K, Na and Cl in the soil increased from 105.9, 18.0, 5.3, 15.4 and 19.4 mg/ kg, respectively at time zero (Table I) to 2,310, 167, 97, 2,210 and 7,612 mg/ kg at salinity level of 20 dS/m (Table 3), respectively, at 720 DAP. The comparison of levels of Na, K, Ca, Mg, and Cl in the soil with plant responses to salinity of irrigation water suggested that increased concentrations of salts in the soil with the passage of time progressively decreased plant survival and vegetative growth in these varieties. The most salt-tolerant cultivar (cv. Khalas) was found to be capable of tolerating high levels of Na (above 2,200 ppm) and Cl (7,600 ppm) in the soil. L. Al-Mulla, N. R. Bhat, and M. Khalil Salt-Tolerance of Tissue-Cultured Date Palm Cultivars under Controlled Environment I World Academy of Science, Engineering and Technology International Journal of Biological, Biomolecular, Agricultural, Food and Biotechnological Engineering Vol:7, No:8, 2013 811 International Scholarly and Scientific Research & Innovation 7(8) 2013 scholar.waset.org/1999.1/16217 In te rn at io na l S ci en ce I nd ex , A ni m al a nd V et er in ar y Sc ie nc es V ol :7 , N o: 8, 2 01 3 w as et .o rg /P ub lic at io n/ 16 21 7 TABLE I THE CHEMICAL ANALYSIS OF A REPRESENTATIVE GROWTH MEDIUM SAMPLE ANALYZED DURING THE INITIATION OF THE STUDY Sample pH ECe Cations (mg/kg) Anions (mg/kg) (dS/m) Ca 2+ Mg K Na Cl CO3 HCO3 Prior to Planting 7.9 2.67 105.89 17.99 5.31 15.41 19.39 <1 30.39 Prior to initiation of Salinity Treatments 8.0 2.08 42.6 11.16 73.49 1.15 51.76 <1 31.73 ECe: Electrical conductivity TABLE II CHEMICAL ANALYSIS OF THE GROWTH MEDIUM USED IN THE SALINITY STUDY AT 180 DAYS AFTER PLANTING Salinity Level (dS/m) pHs ECe Cations Anions Total P Ca Mg K Na Cl CO3 HCO3 N (dS/m) (mg/kg) % (mg/kg) 1.6 7.78 1.9 43.4 8.74 2 51.8 63.4 <1 22.98 0.044 64.78 5 7.62 6.1 448 82.86 117.12 576.8 1173.6 <1 13.48 0.014 84.9 10 7.5 11.84 735.4 62.06 99.64 1221.2 2369.8 <1 15.26 0.022 91.08 20 7.44 19.16 1215.4 48.68 86.7 2003.4 4185.8 <1 15.56 0.02 111.08 ECe: Electrical conductivity of saturated paste extract TABLE III CHEMICAL ANALYSIS OF THE GROWTH MEDIUM USED IN THE SALINITY STUDY AT 720 DAYS AFTER PLANTING Salinity Level (dS/m) pHs ECe (dS/m) Cations (mg/kg) Anions (mg/kg) Ca Mg K Na Cl CO3 HCO3 1.6 8.02 3.54 99.6 19 3.76 70.8 111.2 <1 25.58 5 7.72 19.22 499 48.8 64.6 570.8 1199.8 <1 23.06 10 7.4 58.86 1710.8 134.8 84 2119.6 5374.6 <1 16.58 20 7.7 72.4 2310 167 97 2210 7612 <1 20.2 ECe: Electrical conductivity of saturated paste extract B. Survival and Vegetative Growth The observations on growth performance of palms showed that until 180 DAP, all plants survived in all salinity treatments (Table IV). Effects of high salinity were first manifested at 360 DAP. The cv. Khalas showed the greatest tolerance to high salinity, as indicated by the highest number of plants that survived in the 20 dS/m treatment. Cultivar Nabusaif was found to be the most susceptible to high salinity. At the time of termination of the experiment (720 DAP), 40% of the total number of cv. Khalas survived in the highest salinity. However, all plants of cv. Barhee and 93% of total number of plants in cvs. Al-Ahamad, Kasab, and Khalas and 73% of total number of plants in cv. Nabusaif survived in the 10 dS/ m treatment at 720 DAP. Therefore, it is concluded that cvs. Khalas, Kasab and Barhee had greater degree of tolerance to saline irrigation water than other cultivars, with Khalas being the most tolerant. World Academy of Science, Engineering and Technology International Journal of Biological, Biomolecular, Agricultural, Food and Biotechnological Engineering Vol:7, No:8, 2013 812 International Scholarly and Scientific Research & Innovation 7(8) 2013 scholar.waset.org/1999.1/16217 In te rn at io na l S ci en ce I nd ex , A ni m al a nd V et er in ar y Sc ie nc es V ol :7 , N o: 8, 2 01 3 w as et .o rg /P ub lic at io n/ 16 21 7 TABLE IV SURVIVAL PERCENTAGE OF DATE PALM CULTIVARS IN DIFFERENT SALINITY TREATMENTS Cultivar Salinity Levels Survival Percentage 0 DAP 180 DAP 360 DAP 540 DAP 720 DAP AlAhamad 1.6 100 100 100 100 100 5.0 100 100 100 100 100 10.0 100 100 100 93 93 20.0 100 100 86 13 0 Khalas 1.6 100 100 100 100 100 5.0 100 100 100 100 100 10.0 100 100 100 93 93 20.0 100 100 100 46 40 Nabusaif 1.6 100 100 100 100 100 5.0 100 100 100 100 100 10.0 100 100 93 80 73