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Accueil du site → Doctorat → Afrique du Sud → 2018 → Planting date as an adaptive strategy to improve yield of Chickpea (Cicer arietinum) under under climate change condition in Southern Africa

University of Venda (2018)

Planting date as an adaptive strategy to improve yield of Chickpea (Cicer arietinum) under under climate change condition in Southern Africa

Mubvuma, Michael Ticharwa

Titre : Planting date as an adaptive strategy to improve yield of Chickpea (Cicer arietinum) under under climate change condition in Southern Africa

Auteur : Mubvuma, Michael Ticharwa

Université de soutenance : University of Venda

Grade : Doctor of Philosophy (Plant Production) 2018

Résumé
Planting chickpea genotypes at different dates within the same season may expose the crop to different environmental factors (temperature and moisture) during their vegetative and reproduction stages. Thus, knowledge of optimum planting date that minimises extreme temperature and water stress conditions during crital stages of chickpea plant development may increase biomass and grain yield. The objective of the study was to determine the effect of planting date and genotype on aboveground biomass and grain yield of chickpea under climate change scenario in North Eastern Region of South Africa. The hypothesis tested was that planting date and genotype have an effect on biomass and grain yield of chickpea under climate change scenario. Thus, a study design incorporating a combination of field and modelling experiments was set to run in 2014 and 2015 winter planting seasons at the University of Venda, South Africa. Field experiments determined the effect of planting date and genotype on chickpea flower retention and pod abortion, aboveground biomass and grain yield, water use and radiation use efficiency, whilst modelling experiments calibrated and validated the FAO AquaCrop model to simulate chickpea aboveground biomass and grain yield using climate datasets (1950 - 2100), simulated from 15 global circulation models (GCMs) under the representative carbon dioxide concentration pathways (RCP) 4.5 and 8.5. Field experiments results showed significant effect of planting date and genotype on biomass and grain yield of chickpea. Planting early, particularly under well-watered conditions appeared to be the most suitable sowing period for chickpea in this region. In contrast, late planting had lowest biomass and grain yield. The high grain yield in early planting (1.99 t ha-1) was supported by greater yield components (seed weight (13.8 gm-2) and pod weight 23 gm-2), number of pods per plant (75 pods plant-1) and harvest index (43 %)). Moreover, plant phenological factors such as plant height (46 cm) and number of branches per plant (16 branches) were also greater in early planting, with late planting recording lowest values in all the measured parameters. In addition, the greater biomass and grain yield in early planting compared with the normal and late sowings was caused by greater intercepted radiation (91%), improved flower retention (45.2%) and minimised water use (174 mm) and pod abortion (13.6%). Late maturing genotypes (Range 4 & 5) showed greater water use efficiency of grain yield (7.3 & 7.1 kg ha-1 mm-1) and had the highest radiation use efficiency of grain yield, which was on average 7.2% (0.07 g MJ-1) greater than ICCV9901, and 15.6% (0.13 g MJ-1) greater than Range 1 & 3, but this depended on soil moisture availability. vi The simulation results, indicated a significant increase in temperature (by 4.2 to 5.5 oC) over a period from 1950 to 2100. This increase lead to a concomitant increase in chickpea evapotranspiration and accumulated growing degree days. Moreover, optimal planting date for chickpea shifted from mid-month of April during 1950 to end of May in 2100 and reduced growing season length from 140 days in 1950 to 85 days in 2100. Aboveground biomass increased from 2.0 & 2.05 t ha-1 in 1950 to 4.3 & 4.57 t ha-1 in 2100, respectively in RCP 4.5 and 8.5, whilst grain yield increased from 1.07 & 1.08 t ha-1 in 1950 to 1.68 & 2.21 t ha-1 in 2100, respectively under RCP 4.5 and 8.5. Planting dates that were recommended by AquaCrop model recorded the highest increase in aboveground biomass and grain yield compared with early, normal and late planting dates. Late maturing genotypes (Range 4 & 5) showed greater grain yield and biomass, whilst early and medium maturing genotypes had low biomass and grain yield. The study recommend early planting date together with late maturing chickpea genotypes (Range 4 and 5) in the region so as to improve water use efficiency, radiation use efficiency, heat use efficiency and aboveground biomass and grain yield of the crop under the present time and under climate change scenario. T

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Page publiée le 27 janvier 2019