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

Abu Zurayk, Iad (2019-12)

Thesis (MScAgric)--Stellenbosch University

Thesis

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.

AFRIKAANSE OPSOMMING: Grondversouting is ‘n groot uitdaging vir boere in die Midde-Ooste in die algemeen, maar in die besonder so vir Jordanië waar versouting van besproeiingsbronne addisionele druk plaas op produksiesisteme wat reeds klimaats- en ander grondverwante stres ervaar. Om hierdie uitdagings te oorkom word boere geforseer om voortdurend nuwe verbouingspraktyke te implementeer, terwyl daar gesoek moet word na meer weerstandbiedende kultivars, asook die oorweging van moontlike toedienings van ameliorante om die produksie van hoë kwaliteit vars produkte in ‘n winsgewende en volhoubare manier te verseker. Hierdie studie bestaan uit vier eksperimente en fokus op tamatie en piesang, beide belangrike gewasse wat in die Jordanië vallei verbou word. Die eerste deel van die studie het ten doel gehad om die mees weerstandbiedende kultivars te identifiseer van die twee gewasse wat bestudeer is, gebaseer op ʼn reeks van waargeneemde groei parameters. In die volgende deel van die studie is gepoog om die effektiwiteit van ʼn reeks grond ameliorante en biostimulante te evalueer om sout toleransie in die verskeie kultivars per gewas te induseer soos gedemonstreer word deur vegetatiewe en reproduktiewe parameters. Vir die eerste doelwit is ʼn eksperiment uitgevoer op vyf bepaalde tamatie variëteite, naamlik ‘Majd’, ‘Alam’, ‘Asalah’, ‘Ayah’, en ‘Bahjah’, oor beide ʼn somer en winter aanplanting-seisoen. NaCl is teen vyf toenemende konsentrasies by die daaglikse bemestingsoplossing gevoeg, waarna vegetatiewe kenmerke oor ʼn ses-week periode gevolg is. Daar is waargeneem dat die toename in soutkonsentrasie ʼn betekenisvolle afname in alle plantgroei parameters veroorsaak het. Variëteite het verskil in hul toleransie teen versouting, en het gewissel van tolerant tot vatbaar in die volgorde: ‘Ayah’; ‘Alam’; ‘Majd’; ‘Asalah’; en ‘Bahjah’. In ‘n tweede doelwit is dieselfde prosedures gevolg soos bostaande beskryf is maar vir die twee piesangs kultivars, ‘Grand Nain’ en ‘Paz’. Soos met die tamatie eksperiment was plante onderworpe aan vyf toenemende konsentrasie van NaCl wat by die daaglike bemestingsbesproeiing gevoeg is, vir beide ʼn somer en winter aanplantingsfase van ses weke elk. Resultate dui ʼn betekenisvolle afname in groeitempo en geassosieerde vegetatiewe eienskappe aan met toenemende sout konsentrasie, met ‘Grand Nain’ wat meer groeikragtig en soutbestand vertoon het in vergelyking met ‘Paz’, alhoewel dit nie betekenisvol verskillend was vir alle parameters nie. In die derde doelwit is die effektiwiteit van kompos, glisienbetaine, bakterieë, kelp, swawelsuur en ʼn mengsel van kompos en glisienbetaine geëvalueer vir hulle vermoë om die effek van versouting te amelioreer in die twee tamatie kultivars ‘Ayah’ en ‘Bahjah’, deur beide morfologiese en produksie eienskappe soos plant hoogte, blaar getal, blaarwydte, aantal vrugte en vrug gewig, asook die vars en droë gewigte van die loot en wortels te assesseer. Die kompos behandeling het die beste ameliorasie resultate behaal, en was gevolg deur die kompos en glisienbetaine kombinasie behandeling. Glisienbetaine het meestal vegetatiewe groei en bogrondse produksie bevorder, teenoor die kelp behandeling wat wortelgroei- en gewig bevorder het. Swawelsuur as ʼn behandeling was inkonsekwent en het soms selfs negatief op groei ingewerk, in vergelyking met die kontrole. ‘Ayah’ het beter gevaar in alle parameters in vergelyking met ‘Bahjah’. Die vierde eksperiment was uitgevoer op die twee piesang kultivars, ‘Grand Nain’ en ‘Paz’, oor ʼn twee maande periode, deur ʼn soortgelyke eksperimentele ontwerp te volg as wat gebruik was vir die tamatie eksperiment, maar met enkele aanpassings, soos dat die bakterieë behandeling uitgelaat is, terwyl die glisienbetaine met twee toedieningsintervalle gedoen is. Resultate dui aan dat die kompos en glisienbetaine behandelings meer suksesvol was om versouting te amelioreer as die kelp of swawelsuurbehandelings. ‘Paz’ was konstant meer soutbestand as ‘Grand Nain’. Die gebruik van biostimulante, ongeag of dit ʼn grond of blaartoediening is, en of dit as ʼn enkelproduk of in kombinasie gebruik word, toon aansienlike potensiaal om versouting teen te werk, beide in tamatie en piesang. Verdere studies word benodig om die winsgewendheid van hierdie behandelings te bepaal voordat ʼn kommersiële aanbeveling gemaak kan word.

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