A bright future for the nightshades

MANILA, Philippines - The Philippines has a wealth of indigenous vegetables that can be tapped, utilized and promoted. 

Promoting the  use of indigenous vegetables must be packaged in such a way that people will not only be aware of them, but will actually consume them as food source, and become aware of their medicinal and nutraceutical properties. This, however, required intensive research to support claims on their benefits.

One indigenous vegetable that has great potential but is unknown to many is kawat or black nightshades (Solanum nigrum) from the Solanaceae family.

Known mainly among the settlers of South Cotabato, Sarangani and Sultan Kudarat in Mindanao, kawat is an annual herbaceous plant that can reach up to 100cm in height.

The stem is smooth and bears small hairs, and its flowers are usually white. 

Kawat is also believed to be a food crop with medicinal properties. Consumption of its leaves and fruits as food is widespread, particularly in Africa and Southeast Asia, including the Philippines. 

As food source, its leaves and tender shoots are widely used as vegetables and can be boiled or stewed and used as a relish.

The leaves can  provide rich amounts of protein and amino acids, minerals including calcium, iron and phosphorus, vitamins A and C, fat and fiber as well as methionine, an amino acid that is scarce  in other vegetables. 

Freshly prepared extracts of the plant are found effective in the treatment of cirrhosis of the liver and as antidote to opium poisoning.

An alcoholic extract of leaves is active against Staphylococcus aurens and Escherichia coli.

Berries also possess tonic, diuretic, and cathartic properties and are also useful in heart diseases and as a domestic treatment for fevers, diarrhea, ulcers and eye troubles.

The seeds are reportedly used to treat gonorrhoea and dysuria.

The potential of kawat as food source has been explored and documented through a project titled, “Indigenous Vegetables in Regions I, IV-B and XII.”

The project, implemented by the Science Cluster of UP Los Baños, aimed to help increase vegetable consumption of the country through the collection, development and promotion of the utilisation of indigenous vegetables. 

 Project leader, Rodel Maghirang of UPLB claimed that indigenous vegetables are often compared to the more conventional vegetables in terms of productivity and profitability which could be an unfair comparison since the former have their place in the cropping system not solely as source of nutrition/food, but also for biodiversity, habitation of natural enemies and other indirect benefits.

A total of 52 accessions were collected and 43 species were identified belonging to 20 families.

The highest frequency of citation was from the Solanaceae family, which is represented by native tomato  and kawat  with 94 percent citation as compared to other plant families.

In terms of pollination behaviour, researchers observed it was more effective to bag the plants and not the flowers.

Results showed that flowers not bagged and bagged resulted to 40 percent fruit set, while flowers that were left open resulted to 86.66 percent fruit set.

This showed that it is self-pollinated although cross pollination can also happen.

Given the promising potentials of kawat, extensive research and development initiatives can be further undertaken by promoting it as a conventional crop and for other commercial uses since both the leaves and berries are used as a source of dyes. 

Furthermore, the species can be used as fodder for cattle and goats, just like in some parts of Africa.

The plant can also provide economic opportunities as an additional source of income and livelihood among farmers.