Hidden harvests

There are certain crop plants that are not cropped but edible, containing high nutrients and medicinal value. These crops also called as hidden harvests are capable of providing essential nutrients to our diets besides contributing to household income.

Out of the 12,000 edible plants in the world, a mere fifteen crops provide 90% of the world’s food, with three crops – rice, maize and wheat – making up two-thirds of this total. Most societies today rely on agriculture for their food provision. But that does not mean that agriculture alone provides all food. In all agricultural lands, one can find certain non-crop plants and among them, some are edible. Such edible non-crop plants remain important in all agricultural systems as they are capable of providing essential vitamins and minerals to our diets besides contributing to the family income. That is why these edible non-crop plants are called as the “hidden harvest” of agriculture.

One of the best examples for the rich diversity of edible non-crop plants is the homegardens of Kerala and homegardeners invariably use them. For instance, a study conducted in randomly selected 48 homegardens of Malappuram district recorded about 27 edible herbaceous and shrub species. Of these 27 species, 22 yield edible leaves while the remaining 5 yield edible whole plant. The study also revealed that Centella asiatica, Oxalis corniculata, Phyllanthus urinaria, Portulaca oleracea, Senna occidentalis and Senna tora are very common as they are known for their natural regeneration and quick establishment in the homegardens. Their wide distribution is also owed to the fact that they are known for their food and medicinal values.

Table 1.  Mean nutrient composition (mg per gram) of edible non-crop plant species growing in homegardens of Kerala.

It was also found that homegardeners adopt two ways to collect these edible non-crop plants.  For instance, they make special collection trips to gather plants such as Alternanthera bettzickiana, Alternanthera pungens, Amaranthus caudatus, Amaranthus spinosus, Diplazium esculentum, Senna occidentalis and Senna tora. On the other hand, they collect edible parts of certain species such as Centella asiatica, Oxalis corniculata and Phyllanthus urinaria only during their casual visits.

It may be mentioned here that majority of the households know that all these 27 species are nutritionally rich. However, no scientific analyses to evaluate their nutritive values were conducted, until an attempt was made recently in the Kerala Forest Research Institute. The nutritive status of 11 common edible non-crop plants is given in Table 1.

Proteins are essential for growth and maintenance of our body tissues. According to the Indian National Institute of Nutrition, the daily requirement of dietary protein for an individual is 60g. The present study showed that every one gram of edible part of a species contain 19.3 mg to 54.33 mg of protein, with more protein in Cleome viscosa, Diplazium esculentum, Remusatia vivipara and Alternanthera bettzickiana.  It was also noticed that the protein content in these species was relatively higher than that in common leafy vegetables like palak, lettuce or cabbage.

Human body needs fats to act as energy reserve and to facilitate proper functioning of nerves and the brain. In general, leafy vegetables are poor in fat content. Among the 27 species studied, Remusatia vivipara and Cleome viscosa has the highest fat content (0.015-0.016 mg in one gram). The fat composition in all these edible non-crop species is comparable to those found in conventional leafy vegetables.

Edible non-crop plants are good sources of many nutrients such as protein, fibre, fat and minerals and their nutritive values are higher than that in many commercially cultivated vegetables.

Fibres are nutrients which promote digestive health. It is reported in the Manual of Indian National Institute of Nutrition that a person needs 28-35 grams of fibre per day. All the species investigated in the present study are good source of crude fibre with the highest concentration of 49.8 mg in one gram in Diplazium esculentum. Thus, food prepared from 100 gram of leaves of these edible non-crop plants would meet about 9-12% of the fibre requirement of our body.

Human body needs about 1 gram of calcium daily as it is vital for muscle functioning and neural transmission. Among the species studied, Diplazium esculentum and Talinum cuneifolium are rich in calcium (12.6 to 13.3 mg in one gram). Similarly, about 18 mg of iron is required by an individual on a daily basis for facilitating blood production and oxygen transport. Out of the 27 species, Talinum cuneifolium has the highest iron content (0.8 mg in one gram).

It can be concluded that all the investigated species of edible non-crop plants are good sources of many nutrients such as protein, fibre, fat and minerals and their nutritive values are higher than that in many commercially cultivated vegetables. Majority of these species also possess medicinal value. Thus, their consumption could help in alleviating the problem of malnutrition at no cost.  Popularisation, management and sustainable utilisation of these lesser known plants would also help to maintain the ecology through enhanced plant biodiversity, while contributing to food and nutrition security in the rural landscapes.

U M Chandrashekara
Scientist in charge
Kerala Forest Research Institute Sub Centre,
Nilambur P.O., Malappuram,
Kerala – 679 329
E-mail: umchandra@rediffmail.com