Influence of calcium on yield and quality aspects of potatoes (Solanum tuberosum L.)

Gumede, Thabani (2017-03)

Thesis (MScAgric)--Stellenbosch University, 2017.

Thesis

ENGLISH ABSTRACT: The potato (Solanum tuberosum L.) is an adaptable crop, and modern varieties make its cultivation feasible in numerous parts of the world. The high production potential of the potato ensures that it has the potential to contribute significantly to the world’s food requirements. Correct fertilisation is an important factor in potato production to obtain maximum yields and high quality tubers. Calcium (Ca) is an essential plant element and plays a significant role in the potato plant by maintaining cell membrane and cell wall structure. Recent studies have indicated that tissue Ca level is linked to the quality of various fruit and vegetable products. In the case of potatoes a reduction in tuber internal defects and an improvement in storability can be expected with an increase in tuber Ca. The mechanism of Ca uptake by the potato plant and translocation of Ca within the plant however inhibits the uptake of Ca into the tuber. Thus the present study aims to evaluate the methods to improve Ca tuber content and tuber quality aspects. Potato seedlings of four cultivars (Mondial, Sifra, Lanoma and Innovator) were used in a tunnel where different concentrations of Ca (1.1, 3.2, 6.6 and 9.8 meq Ca L-1) were applied. Tuber mass, shoot fresh mass and shoot dry mass was affected by the Ca application levels and also differed between the cultivars. Mondial, a popular South African cultivar, performed best in terms of tuber yield. Application of 3.2 meq L-1 Ca through drip irrigation was most beneficial to yield parameters (tuber yield, shoot fresh mass and harvest index). To study the Influence of different calcium application levels on potato plants under low temperature growing conditions, potato seedlings of cultivars Destiny and Lanorma, were transplanted into 3 m3 bins containing three different soils (sandy, sandy loam and loam) during the winter season. Three calcium application rates (1.1, 3.2 and 6.6 meq Ca L-1) were applied through drip irrigation. The interaction between Ca application levels and cultivars significantly influenced tuber mass, shoot fresh and dry mass. The influence of Ca as a foliar application on the growth, yield and quality aspects of potatoes was also investigated. Two cultivars (Lady Rosetta and Mondial) were used in a trial where different concentrations of Ca were applied as foliar application or soil drench, during tuber bulking and maturation. None of the parameters measured; tuber fresh mass, tuber number, specific gravity, percentage dry mass or chemical composition was significantly influenced by either the foliar application or soil drench calcium applications. It appears that supplemental Ca applied at these rates and time of plant development has no added benefit on yield or quality aspects of potato tubers. Calcium fertilisation can positively affect both yield and tuber quality but the rate and method of application are of utmost importance. Cultivars also respond differently to Ca application and producers should bear this in mind.

AFRIKAANSE OPSOMMING: Die aartappel (Solanum tuberosum L.) is 'n aanpasbare gewas, en moderne variëteite maak die verbouing daarvan prakties in talle dele van die wêreld. Die hoë produksiepotensiaal van die aartappel verseker dat dit oor die potensiaal beskik om 'n betekenisvolle bydrae tot die wêreld se kosbehoefte te lewer. Korrekte bemesting is 'n belangrike faktor in aartappelproduksie en is noodsaaklik om maksimum opbrengste en hoë gehalte knolle te lewer. Kalsium (Ca) is 'n noodsaaklike voedingselement en speel 'n belangrike rol in die aartappelplant deur die handhawing van selmembraan en selwand struktuur. Onlangse studies het getoon dat Ca inhoud van plantweefsel nou gekoppel is aan die kwaliteit van verskeie groente en vrugte. In die geval van aartappels word 'n vermindering in knol interne defekte en 'n verbetering in opbergings vermoë verwag met ʼn toename in Ca in die knol. Die meganisme van Ca opname deur die aartappelplant en translokasie van Ca in die plant beperk egter die opname van Ca in die knol. Die doel van die huidige studie was dus om metodes te evalueer om die Ca inhoud van die knol en knol gehalte aspekte te verbeter. Aartappel saailinge van vier kultivars (Mondial, Sifra, Lanoma en innoveerder) is gebruik in 'n proef waar verskillende konsentrasies van Ca (1.1, 3.2, 6.6 en 9.8 meq Ca L-1) toegedien is. Knolmassa, halm vars en droë gewig is beïnvloed deur die Ca toedieningsvlakke en het ook verskil tussen die kultivars. Mondial, 'n gewilde Suid-Afrikaanse kultivar, het die beste gevaar in terme van knolopbrengs. Toediening van 3.2 meq L-1 Ca deur drupbesproeiing was baie voordelig in terme van knolopbrengs, halm vars gewig en oesindeks. ʼn Proef is ook gedoen om die invloed van kalsium peile op aartappelplante onder lae temperatuur groeitoestande te evalueer. Aartappel saailinge van kultivars Destiny en Lanorma is geplant in 3 m3 dromme gevul met drie grondtipes (sanderige, sandleem en leem). Drie kunsmis toedieningspeile (1.1, 3.2 en 6.6 meq Ca L-1) is toegedien deur drupbesproeiing. Kalsium toedieningspeile en kultivars het ʼn groot effek gehad op knolgewig, halm vars- en droëgewig. Die invloed van Ca as 'n blaarbespuiting op die groei, opbrengs en kwaliteit aspekte van aartappels is ook ondersoek. Twee kultivars (Lady Rosetta en Mondial) is gebruik in die proef waar verskillende konsentrasies Ca as blaarbespuiting of grondtoediening gemaak is. Geen parameters gemeet; knol varsgewig, knolgetal, soortlike gewig, persentasie droë gewig of chemiese samestelling is statisties beïnvloed deur óf die blaartoediening of grondtoediening nie. Dit blyk dat Ca blaarspuite teen hierdie dosis en tyd van plant ontwikkeling geen bykomende voordeel het op opbrengs of kwaliteit aspekte van moere nie. Kalsium bemesting kan ‘n positiewe effek hê op die opbrengs en kwaliteit van aartappel knolle maar die toedieningspeile en metode van toediening is uiters belangrik. Kultivars reageer ook verskillend op Ca bemesting, ‘n aspek waarvan produsente deeglik moet bewus wees.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/101180
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