Study on effects of superabsorbent polymer on survival and vegetative growth of Ber (Ziziphus spp.) grafted seedling

Abstract
Background and objectives: Ber (Ziziphus spp.), is one of the most important of tropical fruits in hot and dry areas that cultures in southern parts of the Iran, including provinces of Khuzestan, Hormozgan, Bushehr, Sistan and Baluchistan and county of Jiroft and kahnuj. According to the climate conditions of these areas such as low rainfall and high evapotranspiration, water deficit is one of the most important environmental factors that influences on cultivation of plants in these areas and creates problems for farmers that find the solution is essential. On the other hand, one of strategies for challenge with the water deficit problem and reduce the adverse effects of drought stress on the growth and yield of crops and fruit trees in tropical regions is the application of the super absorbent materials.
Materials and Methods: In order to evaluate effects of superabsorbent polymer on survival and vegetative growth of Ber (Ziziphus spp.) grafted seedlings under drought stress, an experiment with 3 levels of irrigation as main plot including: 100, 80 and 60 % of cumulative evaporation from pan class A, 4 levels of superabsorbent polymer: 0, 40, 80 and 120g from A200 source as sub plot, carried out in split plat base on completely randomized block design with three replications on 36 Ber During two years in Date palm and tropical fruits research center in Ahwaz-Khuzestan Province. Before planting, super absorbent polymer was added to the soil of pots in deepness of root development. In this research, Irrigation was carried out by the under pressure irrigation system (Babler). Total water volume needed for each irrigation treatment was compete based on the suggested method of the Food Agriculture Organization (FAO). At first, based on the data of the meteorological data taken from the meteorological station adjacent to the experimental site, the amount of evapotranspiration was calculated, and then the amount of irrigation water base on 60, 80 and 100% of cumulative evaporation from pan class A was compete and accessed into seedlings through the pipeline. At the time of the experiment, the percentage of survival and vegetative growth characteristics such as seedling height, root stock diameter, scion diameter, mean number of leaves per stem length, mean number and length of internodes and chlorophyll content were measured. Statistical analysis of data using SPSS software and mean comparison with Duncan's multiple range test was performed.
Results: Analysis of variance showed that the effects of treatments were significant on some of the studied traits. Based on the results of variance analysis of data, different levels of irrigation and superabsorbent had a significant effect on seedling survival at 5% probability level. As well as the interaction effects of two mentioned factors were significant. Comparing the mean of different levels of irrigation, treatments of 80 and 100% of water requirement were in the same group and did not show any significant difference, but showed significant difference with 60% water requirement. The results showed that under drought stress, application of super absorbent had a significant effect on survival and vegetative growth characteristics such as seedling height, root stock diameter, mean number of leaves per stem length and internodes number. However, on some vegetative growth characteristics such as scion diameter, length of internodes and chlorophyll content did not have a significant effect.
Conclusion: Base on the finding of this research, application 80g superabsorbent and irrigation with 80 % of water requirement for each Ber seedling, the while not significantly reducing the survival and vegetative growth, saved 20% in water use. So, consumption of 80g superabsorbent at the planting time of Ber (Ziziphus spp.) seedlings is recommended.