The effect of plant population and mulching on green pepper (Capsicum annuum L.) production under irrigation

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Date
2010-11
Authors
Hatutale, Gervasius
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University of the Free State
Abstract
English: Green pepper (Capsicum annuum L.) is gaining popularity and the production and consumption thereof is increasing worldwide. Semi-arid regions are characterized by variable and unreliable rainfall which necessitates the use of irrigation for sustainable green pepper production. In this study two field trials were conducted. Objectives of the first trial were to quantify the effect of irrigation and plant population on the growth and yield of green pepper and to optimize its plant population for different water regimes. Four water treatments, full irrigation (781 mm), 70% of full irrigation (627 mm), 40% of full irrigation (497 mm) and dryland (303 mm) and five plant populations (17 689, 23 674, 29 526, 34 979 and 41 496 plants ha-1) were used in this trial. A line source sprinkler irrigation system was used for water application. The trial layout was a split plot design with water applications as main treatments and plant populations as sub-treatments. All treatment combinations were replicated four times. The full irrigation and 40% of full irrigation treatment increased marketable yield with 274% and 162%, respectively. The 70% of full irrigation treatment increased marketable yield with 253%. The marketable yield of all irrigation treatments was significantly higher than that of the dryland treatment. The full irrigation’s marketable yield was however also significantly higher than that of 40% of full irrigation treatment. The optimum plant population for all water treatments, excluding 40% of full irrigation was not reached in this trial because the yield of plant populations (17 689 to 41 496 plants ha-1) used did not reach a turning point, but still increased linearly beyond 41 496 plants ha-1. The objective of the second trial was to quantify the effect irrigation and mulching on yield, water use and water use efficiency. Four water treatments, full irrigation (547 mm), 66% of full irrigation (481 mm), 33% of full irrigation (417 mm) and dryland (303 mm) and two mulching (bare and 9 t ha-1 maize straw) treatments were used. A line source sprinkler irrigation system was also used for this experiment. The trial layout was a split plot design with water treatments as main treatments and mulching rates as sub-treatments. All treatment combinations were replicated four times. Results indicated that green pepper responded well to irrigation. Full irrigation, 66% and 33% of full irrigation treatment produced marketable yield of 37.54, 29.74 and 20.52 t ha-1, respectively. The marketable yield of irrigation treatments was significantly different from each other and they were all significantly higher than that of the dryland treatment which produced a marketable yield of 11.92 t ha-1. As irrigation proceeded over time, the relationship between water use and leaf area index strengthened. The fully irrigated treatment produced the highest water use efficiency. Mulching conserves water by reducing evaporation and mitigates negative effects of water stress on plant growth and yield under semi-arid conditions. At the end of the season, cumulative water use efficiency from the mulched treatment was 6 g m-2 mm-1, significantly higher than that of the bare treatment of 5.3 g m-2 mm-1. Green pepper is very susceptible to water stress and produces poorly under dryland conditions and any irrigation is beneficial to its production. However results also indicated that green pepper has the ability to adapt quite well to high plant populations and has demonstrated its ability to compete for production resources at such populations. The crop also conforms well to the favourable plant growth conditions provided by the mulch. Keywords: marketable yield, water use, water use efficiency, leaf area index, dryland, full irrigation
Afrikaans: Die produksie asook die verbruik van soetrissies (Capsicum annuum L.) het wêreldwyd toegeneem. Semi-ariede gebiede word gekenmerk deur onreëlmatige en onbetroubare reënval wat besproeiing vir volhoubare produksie noodsaak. In dié studie is twee veldproewe uitgevoer. Die doel van die eerste proef was om die invloed van besproeiing en plantpopulasie op die groei en opbrens van soetrissie te kwantifiseer asook om plantpopulasie vir verskillende watervlakke te optimaliseer. Vier waterbehandelings naamlik: vol besproeiing (781 mm), 70% van volbesproeiing (627 mm), 40% van volbesproeiing (497 mm) en droëland (303 mm) asook vyf plantpopulasies (17 689, 23 674, 29 526, 34 979 en 41 496 plante ha-1) is in die proef gebruik. Water is toegedien deur middel van ’n lynbronbesproeiingstelsel. Die proef is uitgelê as ‘n verdeelde perseelontwerp met watertoediening as hoof behandeling en plantpopulasie as sub-behandeling. Alle behandelingskombinasies is vier keer herhaal. Volbesproeiing en 40% van volbesproeiing het die bemarkbare opbrengs onderskeidelik met 274% en 162% verhoog. Bemarkbare opbrengs is met 253% verhoog deur 70% van volbesproeiing en al die besproeiingsbehandelings was betekenisvol hoër as die droëlandbehandeling. Volbesproeiing se bemarkbare opbrengs was ook betekenisvol hoër as die 40% van volbesproeiingbehandeling. Die optimum plantpopusasie vir al die waterbehandelings, uitsluitende die 40% van volbesproeiingbehandeling is nie bereik nie. Opbrengs het bly toeneem by die hoogste plantpopusisie (41 496 plante ha-1) en nog geen draaipunt is bereik nie. Die doel van die tweede proef was om die invloed van besproeiing en deklaag op opbrengs, waterverbruik en waterverbruiksdoeltreffendheid te kwantifiseer. Vier waterbehandelings, volbesproeiing (547 mm), 66% van volbesproeiing (481 mm), 33% van vol besproeiing (417 mm) en droëland (303 mm) asook twee deklaagbehandelings (skoon en 9 t ha-1 mielie reste) is toegepas. ’n Lynbronbesproeiingstelsel is ook in dié proef gebruik. Die proefuitleg was ’n verdeelde perseeluitleg met waterbehandeling as hoof behandeling en deklaag as sub- behandeling. Alle behandelingskombinasies is vier keer herhaal. Resultate het getoon dat soetrissies goed reageer op besproeiing. Volbesproeiing, 66% and 33% van volbesproeiing het ’n bemarkbare opbrengs van 37.54, 29.74 en 20.50 t ha-1 onderskeidelik gelewer. Die bemarkbare opbrengs van die onderskeie besproeiingsbehandelings het betekenisvol van mekaar verskil en dit was ook betekenisvol hoër as die droëlandbehandeling wat ’n bemarkbare opbrengs van 11.92 t ha-1 gelewer het. Soos daar voortgegaan is om te besproei het die verwantskap tussen watergebruik en blaararea-indeks versterk. Die volbesproeiingsbehandeling het die hoogste waterverbruiksdoeltreffendheid getoon. Deklaag het evaporasie verlaag en sodoende water bewaar wat weer die negatiewe effek van waterstremming op plantgroei en opbrengs onder semi-ariede toestande verminder het. Die kumulatiewe waterverbruiksdoeltreffendheideffek van die deklaagbehandeling aan die einde van die seisoen was 6 g m-2 mm-1 en was betekenisvol hoër as die van die geen deklaagbehandeling (5.3 g m-2 mm-1). Soetrissies is baie gevoelig vir waterstremming en opbrengs is swak onder droëlandtoestande. Enige besproeiing kan voordelig wees vir die produksie van soetrissies. Resultate het ook gewys dat soetrissie plante die vermoë het om te kompeteer vir hulpbronne onder hoë plantpopulasies. Die gewas reageer ook goed op die gunstige groeitoestande wat deur die deklaag geskep is. Sleutelwoorde: bemarkbare opbrengs, watergebruik, watervebruiksdoeltreffendheid, blaararea-indeks, droëland , volbesproeiing
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Keywords
Bell pepper Irrigation, Bell pepper, Soils, Irrigated, Capsicum annuum L., Dissertation (M.Sc.Agric. (Soil, Crop and Climate Sciences))--University of the Free State, 2010, Mulching
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