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Lost crops: Food for thought for Zimbabwe

by Praxedis Dube1, Rico Ihle1, Wim Heijman1 and Paul Struik2
22 Jul 2017 at 18:44hrs | Views
Many do remember the yesteryear song of Oliver Mtukudzi "Tsika dzedu" in which the musician pitched the importance of the traditional way of living, when people used to consume traditional leafy vegetables like nyevhe (spider flower) and munyemba (cowpea leaves).

A much debated question is to what extent these vegetables contribute to food and nutrition security. Some argue that people only need small quantities of traditional leafy vegetables to accompany the carbohydrate staples, hence the contribution of these vegetables to food and nutrition security is relatively small. Others allude that traditional leafy vegetables determine the intake of carbohydrate staples, pitching their importance in the daily diets of many. Nutritionists are worried about the low micronutrient contents in the carbohydrate staples. Although bio-fortified staple crops like maize are considered to address selected nutrient deficiencies, they can target only a few nutritional factors, e.g. quality protein maize delivers protein. Traditional leafy vegetables are ideal to complement the low micronutrient levels in carbohydrate staples as they are rich in vitamins A,  C and E, iron, zinc, fibre, minerals and proteins. The most commonly consumed types of traditional leafy vegetables across Africa include: spider flower, moringa, pumpkin leaves, pigweed, cowpea leaves, black jack, okra, jute, sweet potato leaves, cassava leaves and nightshade. Some of these vegetables, like sweet potato, are double-purpose crops: one can harvest the leaves as vegetable and the tuberous roots as carbohydrate staple.

In Zimbabwe, traditional leafy vegetables may grow naturally in the forest, fallow lands or in farmers' fields or selected species are grown in the gardens. They are mainly gathered from the wild or grown for consumption and selling. They can be produced even by poorly equipped farmers and thrive in marginal areas like Binga as well, where natural conditions for farming are harsh and farmers often use traditional cropping technologies. These vegetables account for over 80% of all leafy vegetables consumed in East Africa. In Zimbabwe, over 75% of the population use them during the rainy season. This  underlines the importance of these crops for food and nutrition security. They can, therefore, increase food and nutrition security of many households that experience financial difficulties- a situation many households in Zimbabwe are often facing as they can be gathered from the wild or can be produced with minimum resources. However, their potential effect on the food and nutritional security to the Zimbabweans depends, among other things, on seasonal availability which in turn affects their prices and, thus, the frequency and amounts of consumption. The availability of seed of good quality to the producers of these vegetables is therefore a key determinant of the duration of the growing season, the level of yields, product qualities and vegetable varieties offered in markets across the country.

The quality of seed in terms of proper age, high viability, high germination rates, high seedling vigour as well as high purity decide upon the crop stand of these vegetables in the  field. An optimal crop stand is profitable to the farmers as they may be able to increase their income from the labour used for cultivation. Seed is the first link in the food production chain as it is the key production factor determining the genetic resources and quality of the food grown. Some traditional leafy vegetable species like spider flower, are domesticated or semi-domesticated versions of the weedy species growing under the natural conditions found in the various regions of Zimbabwe. Their survival in their habitants is anchored on certain adaptive traits such as slow and low germination behaviour. Such characteristics ensuring survival in the wilderness pose, however, a challenge to farmers for getting a desirable crop stand in their fields. This is one of the reasons why farmers fail to meet the growing demand of these vegetables. While a lot of work has been done on the demand and consumption of traditional leafy vegetables, the thrust should now focus on improving the quality of seeds used in production of traditional leafy vegetables to upgrade their harvest potential and all year round production. This might not only help farmers to meet the rising demand in the country's urban centres, but also to boost and diversify farmers' income and, thus, facilitate rural development in the growing regions.

The economic potential of traditional leafy vegetables in Zimbabwe
Although their economic potential for both seed and vegetables is yet to be realized in Zimbabwe, a survey conducted in some areas of Zimbabwe showed that a table-spoonful or pet coke cola lead of seed costs US$2.00 and US$0.50 respectively or US$50 per kilogram. When the above seed weights and prices were calculated and estimated per hectare of spider flower for one season, the gross margin valued at US$6 500 excluding the by-products. Considering that these vegetables are produced with minimum resources, a gross margin of US$6 500 is comparable to a moderately resourced farmer venturing into maize seed production expecting a yield of five tons per hectare but hardly getting a gross margin of US$6 500. If the quality of the seed can be improved and becomes more homogeneous, farmers would benefit by realizing better yields which would translate into improved food and nutrition security on the consumption side. While considerable progress in this regard has been made in East and West Africa, little has happened in Zimbabwe. There, it is reported that switching from own-produced to certified seed increased farmers' market gross value by 213% in the period between 2001 and 2006.   

In Zimbabwe, research has shown that the consumption of traditional leafy vegetables is relatively higher during rainy season (October to March) than during the dry season. During the dry season traditional leafy vegetables are mainly consumed dried. By improving the quality of the dried traditional leafy vegetables through research the nutrition of many people may improve. Such research may focus on improving the quality of dried traditional leafy vegetables to other modernised products like flour to bake cakes, pies or samosas that are acceptable throughout the generations.

How to improve seed quality for boosting production of domestic traditional leafy vegetables?
Harvesting the seed before the temperatures drop can be beneficial to traditional leafy vegetable farmers as they are assured of high germination in the next season if all other  factors are maintained under control. Such factors include preventing seed from being exposed to moisture or humid conditions during storage, rodents attack and excessive heat. Sometimes poor germination can be attributed to environmental conditions during crop growth. For example, exposure to low temperatures during growth of the seed crop may induce seed dormancy. This scenario is undesirable to farmers as it results in low yields per unit area. Improving the quality of traditional leafy vegetable seeds should be given the same priority as in the cases of maize, groundnut or other staple crops. Usually farmers harvest seeds well after collecting some of their major crops from the fields, and some do not even harvest the seeds at all. In addition to a proper harvesting time, the farmers cropping spider flower are advised to first soak the seed overnight before planting to optimise crop stand.

Implications for stakeholders of the traditional vegetables supply chain
Although traditional leafy vegetables are widely consumed in Zimbabwe, some species may be more preferred than others among regions. In this country, for example, the southern part tends to like the cowpea leaves and spider flower, whereas the north-eastern communities prefer pumpkin leaves. Likewise, some regions tend to prefer fresh vegetables whereas other regions prefer them dried. This kind of information may be very useful to seed producers, producers and marketers, they would be better positioned to target their markets. This challenge can be solved by policy makers through creating a conducive and transparent marketing environment for seed producers, producers and marketers by, for example, making use of revolutionizing ICT technology being used in many African countries for improving market transparency.

Currently in Zimbabwe, the seed laws do not recognise the farmers' saved seed compounded by outdated laws (enacted in 1960s) which criminalise the sale of the seed by farmers. Political reform of this legislation for encouraging the growth of the domestic traditional vegetables supply chain might benefit domestic seed and vegetable producers. Such policies might yield a number of positive side-effects such as supporting viability of livelihoods in the rural growing regions throughout Zimbabwe. Whilst improving producers' yield through breeding, the researchers should be careful in losing the important traits of these vegetables like nutritional ones which make these crops so valuable. Researchers as well as policy makers should encourage producers to continue growing their traditional varieties alongside with improved varieties in order to maintain genetic plurality for future generations.

The authors are affiliated with the Department of Social Sciences, Agricultural Economics and Rural Policy Group1 and Centre for Crop Systems Analysis, Plant Sciences Group,2 at Wageningen University in The Netherlands. Feedback:

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Source - Praxedis Dube1, Rico Ihle1, Wim Heijman1 and Paul Struik2