Faculty of AgriSciences

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https://scholar.sun.ac.za/handle/10019.1/9

The Faculty of AgriSciences at Stellenbosch University (SU) is held in high esteem at national and international levels for the quality of its training and research and also as consultant in the agricultural and forestry industry.

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Browsing Faculty of AgriSciences by Author "Abu Zurayk, Iad"

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    A study of the impact of salinity on growth and development of important tomato and banana cultivars of the Jordan Valley with an assessment of the efficacy of biostimulants as ameliorants for increased tolerance to salinity
    (Stellenbosch : Stellenbosch University, 2019-12) Abu Zurayk, Iad; Hoffman, L. (Lynn) (Horticulturalist); Lotze, Elmi; Oosthuyse, S. A.; Stellenbosch University. Faculty of Agrisciences. Dept. of Horticulture.
    ENGLISH ABSTRACT: Soil salinity is a major challenge to farmers in the Middle East in general, but particularly so in Jordan, where salinization of irrigation water sources puts additional pressure on production systems, already experiencing significant climatic and soil-related stresses. To meet these challenges farmers are forced to implement new cultural practises, while consistently having to screen for more tolerant cultivars, in addition to considering the application of ameliorants, in order to deliver high quality fresh produce in a profitable and sustainable manner. This study, consisting of four experiments, focused on tomato and banana, both major crops grown in the Jordan valley. The study aimed in the first two trials to identify the most tolerant cultivars of these two crops, as determined through a range of growth parameters. The next part of the study aimed to determine the efficiency of a range of soil ameliorants and biostimulants in the various cultivars per crop to increase their resistance to salinity as demonstrated through vegetative and reproductive growth parameters. For the first objective an experiment was conducted on five determinate tomato varieties, namely ‘Majd’, ‘Alam’, ‘Asalah’, ‘Ayah’ and ‘Bahjah’ over a summer and a winter planting season, through the addition of NaCl at five increasing concentrations to the daily fertigation solution, where after vegetative traits were observed over a six-week period. Results showed cultivars differed in their resistance to salinity and ranked in general from tolerant to susceptible: ‘Ayah’; ‘Alam’; ‘Majd’; ‘Asalah’ and ‘Bahjah’. In the second objective the same procedures as described above was followed, but where two banana cultivars, ‘Grand Nain’ and ‘Paz’ were assessed for salinity tolerance. Similar to the tomato experiment, plants were subjected to five increasing NaCl concentrations that was added to the daily fertigation solution, for both a summer and winter planting phase of six weeks each. Again, the increase in salinity concentration significantly decreased all plant growth parameters. In addition, results showed a significance decrease in growth rate and associated morphological traits with increasing salinity concentration, with ‘Grand Nain’ being the more vigorous cultivar compared to the ‘Paz’ cultivar, although not significant so for all parameters. In the third objective the efficacy of compost, glycine betaine, bacteria, kelp, sulphuric acid and a mix of compost and glycine betaine treatments was evaluated for their ability to ameliorate the effect of salinity on the two tomato cultivars, ‘Ayah’ and ‘Bahjah’, by assessing both morphological and production traits such as plant height, leaf number, leaf width, fruit number and weight, along with fresh and dry weights of the shoot and root. The compost treatment produced the best amelioration result, and was followed by the compost and glycine betaine combination treatment. Glycine betaine mostly promoted vegetative growth and above ground production, whereas the Kelp treatment benefited root growth and weight. Sulphuric acid as a treatment was inconsistent and at times even impacted negatively on growth compared to the control. ‘Ayah’ performed significantly better in all parameters compared to ‘Bahjah’. The fourth experiment was conducted on the two banana cultivars ‘Grand Nain’ and ‘Paz’, over a two-month period, following a similar experimental design than used for the tomato trial, with a few small amendments, as the bacteria treatment omitted, while the glycine betaine was applied at two application intervals. Results indicated that the compost and glycine betaine treatments were more successful in ameliorating salinity than the kelp or sulphuric acid treatments. ‘Paz’ consistently showed greater saline tolerance than ‘Grand Nain’. The use of biostimulants, whether applied to the soil or as a foliar application, used either as a single product or in combination, showed considerable potential to ameliorate salinity, both in tomato and banana. More studies is required to determine the profitability of these approaches before a commercial recommendation can be made.