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

[摘要] English: Green pepper (Capsicum annuum L.) is gaining popularity and the production andconsumption thereof is increasing worldwide. Semi-arid regions are characterized by variableand unreliable rainfall which necessitates the use of irrigation for sustainable green pepperproduction. In this study two field trials were conducted. Objectives of the first trial were toquantify the effect of irrigation and plant population on the growth and yield of green pepperand to optimize its plant population for different water regimes. Four water treatments, fullirrigation (781 mm), 70% of full irrigation (627 mm), 40% of full irrigation (497 mm) anddryland (303 mm) and five plant populations (17 689, 23 674, 29 526, 34 979 and 41 496plants ha-1) were used in this trial. A line source sprinkler irrigation system was used for waterapplication. The trial layout was a split plot design with water applications as main treatmentsand plant populations as sub-treatments. All treatment combinations were replicated fourtimes. The full irrigation and 40% of full irrigation treatment increased marketable yield with274% and 162%, respectively. The 70% of full irrigation treatment increased marketable yieldwith 253%. The marketable yield of all irrigation treatments was significantly higher than thatof the dryland treatment. The full irrigation's marketable yield was however also significantlyhigher than that of 40% of full irrigation treatment. The optimum plant population for allwater treatments, excluding 40% of full irrigation was not reached in this trial because theyield 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% offull irrigation (481 mm), 33% of full irrigation (417 mm) and dryland (303 mm) and twomulching (bare and 9 t ha-1 maize straw) treatments were used. A line source sprinklerirrigation system was also used for this experiment. The trial layout was a split plot designwith water treatments as main treatments and mulching rates as sub-treatments. All treatment combinations were replicated four times. Results indicated that green pepper responded wellto irrigation. Full irrigation, 66% and 33% of full irrigation treatment produced marketableyield of 37.54, 29.74 and 20.52 t ha-1, respectively. The marketable yield of irrigationtreatments was significantly different from each other and they were all significantly higherthan that of the dryland treatment which produced a marketable yield of 11.92 t ha-1. Asirrigation proceeded over time, the relationship between water use and leaf area indexstrengthened. The fully irrigated treatment produced the highest water use efficiency.Mulching conserves water by reducing evaporation and mitigates negative effects of waterstress 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, significantlyhigher 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 conditionsand any irrigation is beneficial to its production. However results also indicated that greenpepper has the ability to adapt quite well to high plant populations and has demonstrated itsability to compete for production resources at such populations. The crop also conforms wellto the favourable plant growth conditions provided by the mulch.Keywords: marketable yield, water use, water use efficiency, leaf area index, dryland, fullirrigation

[发布机构] University of the Free State