Curated Content

No information is available on responses of South African taro landraces to water stress. The objective of this study was to evaluate the responses, and mechanisms thereof, of taro to water stress under controlled and field conditions. Taro landraces were collected from rural areas in KwaZulu-Natal, South Africa. A pot trial was planted in tunnels at the University of KwaZulu-Natal with two factors: three landraces and water stress (NS – no stress, IS – intermittent stress and TS – terminal stress), replicated six times. For NS, soil water content (SWC) was maintained at 75% field capacity (FC). IS involved watering pots to 75% FC during crop establishment, and allowing SWC to deplete to 30% FC during the vegetative stage, before returning to 75% until harvest maturity. For TS, SWC was maintained at 30% FC for the entire growing period. Field trials were planted in October 2010, with irrigation (full irrigation versus rainfed) as a main factor and landrace type as sub-factor, replicated three times. SWC was monitored weekly. Emergence, plant height, leaf number, leaf area, LAI, vegetative growth index (VGI) and stomatal conductance (SC) were determined weekly. Results from both pot and field trials showed that taro landraces were slow to emerge (~49 days). There were significant differences (P<0.001) between landraces with respect to final emergence. Taro growth (plant height, leaf number and leaf area), for both trials, was shown to be significantly (P<0.05) reduced by water stress. Under field conditions, SC, LAI and VGI were significantly (P<0.05) lower under rainfed conditions compared with irrigated conditions. It is concluded that emergence and vegetative growth parameters of KwaZulu-Natal taro landraces are sensitive to water stress. Data from this study will be used to calibrate AquaCrop and presented as a possible option to manage taro under dryland and irrigated conditions in the warm subtropical areas of South Africa.

Historically, traditional cropping systems are based on diversification, thus making a significant contribution to food security for the household. Intercropping may offer farmers the opportunity to mimic this diversity. The aim of this study was to evaluate the productivity of a taro-bambara intercrop. The intercrop combinations were 1:1 and 1:2, compared with taro and bambara sole crops. Growth parameters and yield components were determined separately for each crop. Thereafter, land equivalent ratio (LER) was calculated to evaluate the productivity of the intercrop. Plant height of taro, as the main crop, was not significantly affected by intercropping. However, leaf number was significantly affected (P<0.001). Intercropping taro resulted in reduced leaf number compared with the sole crop; leaf number in response to the 1:2 intercrop was significantly lower than that of 1:1 intercrop. Bambara growth was significantly (P<0.05) affected by intercropping in that plants were taller and had more leaves when intercropped with taro. Taro yield was not significantly affected by intercropping, although yield generally decreased under intercropping compared with the sole crop. Bambara yield was also not significantly affected by intercropping. The LER showed that intercropping was more productive than sole cropping. The 1:1 intercrop had a LER of 1.71 compared with 1.36 for the 1:2 intercrop. It is concluded that although intercropping had variable effects on the growth of both taro and bambara, there was an agronomic advantage to intercropping.

AquaCrop is a crop model that simulates yield response to water developed by FAO and is appropriate to consider effects where water is the limiting factor for crop production. AquaCrop was calibrated for amaranthus (Amaranthus cruentus L. ex Arusha), a leafy vegetable, and taro (Colocasia esculenta (L.) Schott.), a wetland perennial, with an edible starchy corm as a tuber crop. The weather datasets were obtained from the climate database at Agricultural Research Council-Institute of Soil, Climate and Water in Pretoria for specific sites and years of the trials. The first step in the model is to select the correct type of crop, create a new crop and name it. Observed soil parameters from the experimental sites were used to create soil files in AquaCrop; the model is sensitive to amount of water available in the soil between field capacity and permanent wilting point. The crop parameters under optimal water availability were adjusted according to observations from field trials conducted for each crop. The first parameter checked was canopy cover, representing the expansion of the leaf canopy under non-limiting conditions, where the maximum value, CCx, (90% for amaranthus and 78% for taro) and the time take to reach CCx were needed. The total length of the cropping season should be checked and also time to the start of senescence. However, for the leafy vegetable this was not necessary as the crop was harvested while the leaves were green. The effect of water stress must be included via the Ks factor for water stress according to stomatal closure at a specific soil water availability, as measured in the field trials. The water productivity normalised for ETo and CO2 concentration (32 g m-2 for amaranthus and 15 g m-2 for taro) was calculated from field data of biomass accumulation and transpiration standardised for ETo. The reference harvest index (HIo) was 85% for amaranthus and 83% taro, respectively. Once the model is calibrated with data from single sites, it must be verified with independent data from different sites and/or series of experiments. The calibrated AquaCrop model will be used to promote the introduction of these underutilised vegetables on irrigation schemes since optimal irrigation strategies can be developed. Best management practices, soil types, sowing dates and locations can be selected from model runs at a range of sites.

Intercropping involves the cultivation of two or more crops on the same field in both space and time. It is a farming practice that has existed throughout history and one which mimics natural diversity. Intercropping has several advantages over monocropping which include improved resource utilization of light, water and nutrients, as well as yield stability over time. It is a practice that historically contributed towards food security within communities. It offers a sustainable alternative to the more widely practiced monocropping. However, it has been widely regarded as a primitive practice and this has created a scenario whereby there was scant research done on intercropping. 

The impact of global warming to the Namibian economy is enormous and already costs the government billions. Nevertheless the changing conditions also bear opportunities and potentials for growth, development and economic stability.

Namibia is plagued with a dry climate and poor soils, and the country’s small-scale farmers produce the lowest agricultural yields in the world. With an estimated population of around two million, Namibia has the world’s second lowest population density. As global climate change impacts become more evident, Namibia is likely to be one of the most severely affected areas.

The Community Based Adaptation (CBA) project areas were located in Northern Namibia and consisted of five regions: Omusati, Ohangwena, Oshikoto, Oshana and Kavango. The majority of the community members were subsistence farmers who depended highly on rain-fed dry land crops and livestock rearing both for subsistence and income generation.

Climate change induced rising temperatures, irregular rainfall, prolonged and intensified drought and flood incidents have resulted in food and water insecurity, threatening the communities’ livelihoods, especially those of the marginalized groups within the communities: women and orphaned children from HIV/AIDS-affected families.

Namibia is the driest sub-Saharan nation and is among the countries most severely affected by climate change. This is threatening food security, particularly in Namibia’s densely populated northern region, where more than half of the country’s 2.1 million residents live. The main activity in this region is subsistence agriculture, which is primarily rainfed. Older people are often left to carry out the agricultural work, while the younger generation moves to urban areas.

Both crop production and livestock farming are characterised by low levels of productivity. In the case of crop production and the main crops of millet and corn, this is primarily due to infertile soil and unreliable rainfall patterns. Where possible, farmers apply shifting cultivation practices and periodically clear new areas. Since organic and mineral fertilisers are rarely used, soil fertility rapidly diminishes. A number of small-scale farmers irrigate their fields, but the potential for irrigated agriculture is limited; in addition, this is a very capital-intensive method.

Due to climate change, additional productivity losses are expected in the region. Crop production, in particular, is already being affected by climate change. Temperatures and rainfall variability are increasing rapidly, and droughts and floods are becoming more and more frequent. By 2050, it is anticipated that it will only be possible to practise rainfed agriculture using current methods in Kavango East and Zambezi.

Despite the crop losses that are already associated with climate change, very few small-scale farmers are applying climate-adapted cultivation methods.

H.E Dr. Hage G. Geingob, President of the Republic of Namibia signed the Paris Agreement on behalf of Namibia at the signing ceremony at the U.N head Quarters in New York Yesterday (22 April 2016). A historic total of 171 Members signed the agreement on the same day. It is for the first time that the United Nations receives such a big number of signatories on the 1st day.

I believe this agreement will help us as a country to tackle the challenges of climate change and to capitalize on opportunities that will lead to sustainable development of our nation.

Furthermore, we are excited as Namibia to be part of this journey where as we pledged to play our part to reduce gas emmissions by 89% by 2030 as stipulated in our Intended Nationally Determined Contributions (INDC) document we submitted to the UNFCCC in 2015.

I am sure that all of us will agree that tackling the issue of climate change is crucial for Namibia condsidering how vulnerable our country is to climate change.

The Paris Agreement commits developed countries to take the lead in scaling up financial support for tackling climate change in developing countries.

In this regard, Namibia being a signatory to the Paris Agreement it has an opportunity to access such funding through institutions like recently operationalized Green Climate Fund.

The fund will assit the country is tackling climate change related challenges such as water insecurity; food insecurity and energy insecurity.

Successful crop stand establishment, a critical prerequisite for efficient crop production, is primarily determined by propagule quality. Taro [C%casia escu/enta (L.) Schott] corms of different sizes (80-100 g corm-1, 40-60 g corm-1 and 20-30 9 corm-1) that had been stored in soil pits at different depths (10,20,30,40 and 50 cm) were compared for stand establishment, leaf area and yield during two seasons, under rainfed (upland) conditions. Propagule size and pre-planting storage depth increased both the number of plants reaching the third leaf stage and leaf area per plant one month after planting. The large propagules improved stand establishment and yield significantly (P<0.01) better than the smaller propagules. For a” propagule sizes, the optimum storage depth to enhance taro propagule performance for crop production was – 40 cm. When the large propagules were compared with the smaller propagules at the optimum pre-planting storage depth, there was 10% to 30%, no difference and 5% to 35% improvement il’) leaf area, stand establishment and yield, respectively. This study confirmed the potential role of local knowledge in traditional agriculture, and the findings can be used to extend the planting season for dryland taro production in South Africa.

There is a strong relationship between gender, livelihood and poverty. This relationship has been explored by many researchers, and significant to their findings is the relationship between climate change and people’s livelihood, which is dependent on natural resource base and poverty.