Nozipho M. Motsa and A.T. Modi. Ethekwini University Research Symposium (5-6 April 2016)

Transcription

1 Yield and nutritional content of sweet Potato (Ipomoea batatas L.) grown under natural environment of Umbumbulu: Impacts on livelihood and socio-economic aspects Nozipho M. Motsa and A.T. Modi Ethekwini University Research Symposium (5-6 April 2016)

2 Introduction Sweet potato is widely cultivated as a food security (for vitamin A deficiencies) crop It has the ability to adapt to a wide range of environmental conditions grows well with low input requirements marginal soils under adverse weather conditions Its production is predominantly done by resourceconstrained farmers Mostly women in small plots Harvested after the staple crop Food security crop Referred to as poor-man s crop

3 Introduction cont. South Africa may be food secure at national level, but household food security is still a problem Both in terms of energy and micronutrient deficiencies Sweet potato is still grossly underutilised despite its versatility and rich nutritional benefits Vitamin A deficiency (VAD) in South Africa is still a serious health problem Highest prevalence was concentrated in Limpopo (43.5%) and KwaZulu-Natal (38.9%) provinces Umbumbulu environment is suitable for sweet potato production Moist coast hinterland and ngongoni veld soils topography.

4 New sweet potato lines/cultivars has been bred to address food insecurity, and they still need to be tested for production by small-scale farmers. Umbumbulu farmers were predominantly producing taro. A need for dietary diversity was perceived, hence the reintroduction of sweet potato with particular attention given to the orange-fleshed cultivars.

5 Objective The main aim was to see whether sweet potato s re-introduction will have an impact on the livelihoods and socioeconomic aspects of the farmers. The objective of the study was therefore, to investigate growth, yield and nutritional content of orange-fleshed sweet potato cultivars under the natural environment of Umbumbulu.

6 Materials and Methods Planting material:(lines from UKZN breeding programme) Soil type: Sandy and clay Plant population: plants / ha Experimental design: RCBD Replicates: 3 Planting dates: Summer: last week of October 2012 and 2013 Figure 1: General outline of a sweet potato leaf (adopted from Huaman, 1992)

7 Materials and Methods cont. Figure 2: Construction of ridges for planting Figure 3: : Leaf porometer for measuring stomatal conductance

8 Materials and Methods cont. Data collected Vine length Leaf number Stomatal conductance Chlorophyll content index Soil water content Storage root yield Nutritional content: leaf total antioxidant activity, total carotenoids and betacarotene content were measured using spectophotometry

9 Results and discussions Figure 4: Vine length and leaf numbers of the three cultivars grown at Umbumbulu during 2012/13 and 2013/14 seasons

10 Results and discussions cont. Figure 5: Chlorophyll content of sweet potato cultivars grown during 201/13 and 2013/14 at Umbumbulu

11 Stomatal conductance (mmol m -2 ) Results and discussions cont LDS (P=0.05) = /13 A40 A Weeks after planting Figure 6: Stomatal conductance of different sweet potato cultivars during 2012/13 growing season

12 Storage roots yield (t ha -1 ) Starch content (%) Results and discussions cont / /14 LSD (P=0.05) = / /14 LSD (P=0.05) = A40 A45 Cultivars A40 A45 Cultivars Figure 7: Storage root yield Figure 8: Starch content of sweet potato cultivars grown at Umbumbulu

13 Results and discussions cont. Figure 9: Beta carotene content in the different sweet potato cultivars Figure 10: Storage roots infested by sweet potato flea beetle

14 2013/ /13 Table 1: Climatic data for the three experimental locations during the summer season Temp ( o C) Climatic conditions (mm) Season Months Max Min Rain ETo Deficit November December January February March * 449.2* November December January February March * 524.9*

15 Conclusions Constantly warm temperatures at Umbumbulu during planting period favoured and enhanced crop establishment and vegetative growth. This allowed root filling to begin on time thus crop was able to give higher yields (at 120 days). Storage root yield and nutritional content was fairly constant in both growing seasons Yield was maintained without applying fertilizers Cultivar A45 contained enough β-crotene within recommended daily allowance (RDA) of vitamin A

16 Harvesting was done while rains were still being received, thus, most of the storage roots were infested by sweet potato flea beetle which made tiny tunnels on the storage roots rendering it not market-worthy. This have a negative effect on the socioeconomic status of the community Cultivar A40 was shown to be more adapted to Umbumbulu growth condition In order to improve yields and shelf life of sweet potato, farmers should be encouraged to practice basic agronomy and planting at the right time.

17 Acknowledgements Special thanks to Sida, OWSD and UKZN (Crop Science) for financial support. The Umbumbulu community for their massive contribution to this work. UNIZULU for allowing this opportunity.