Cowpea (Vigna unguiculata) Variety Trial at ECHO

Grain legumes can be a tremendously important tool in combating malnutrition. The term “grain legume” or “pulse crop” is used for leguminous crops (e.g. cowpea, beans, peanut), the seeds of which are harvested dry and then cooked in various ways or made into flour. Being legumes, they provide a rich source of protein as well as vitamins, minerals and energy. According to Lost Crops of Africa (Volume II: Vegetables), cowpea (Vigna unguiculata) is the second-most planted grain legume on the continent of Africa. Yet, it is being “lost” in the sense that efforts to maximize its potential to increase nutrition are often lacking.

Experimentation with cowpea is merited because of its drought tolerance (some varieties require as little as 300 mm rainfall) and adaptability to a wide range of soil conditions. Additionally, its deep roots stabilize the soil, and the plant acts as a ground cover. It also fixes atmospheric nitrogen, improving the soil in the process. The seeds themselves are low in anti-nutritional factors, and some varieties cook quickly which can be an important consideration where fuel wood is scarce. The seeds also come in a wide variety of colors (Figure 9): white, red, black, tan, some with black eyes and some speckled.

Last year, we did a variety trial at ECHO to determine which varieties produce the highest marketable yields of dried seeds at our location. By focusing on marketable yield, we automatically screened for tolerance to the pod-damaging effect of piercing insects. In addition to five varieties already listed in our seed catalog, 21 additional accessions were included in the trial. Each of the 26 varieties was randomly assigned to four plots in the experiment. Seeds were sown on March 13, 2008. Considering that March is very dry and Florida sands are extremely deficient in nutrients, the plots were fertilized and watered as needed. Weekly harvests of mature/dry pods began on June 4 and ended on July 9. Pods (with seeds inside) were dried and weighed weekly. At the end of the season, all the pods were shelled and the seeds weighed.

The top five varieties, in terms of seed yield (Table 1) were ‘Ejotero’, ‘Reddish Brown’, Tohono O’odham’, ‘V01-020’ and ‘Cerocahui’. Statistically, yields of these five varieties were similar to each other. Interestingly, weekly pod yield data (not shown) showed that ‘Cerocahui’ yielded heavily during the first week of harvest and then dropped off with subsequent harvests. ‘Ejotero’ was also a good early-producing variety. ‘V01-020’ did not produce many pods the first week of harvest, but it yielded steadily between the 2nd and 5th weeks of harvest.

By the 6th week of harvest, yields of all the varieties were close to zero and the trial was ended. Had the trial been extended, it is possible that ‘Guarijio Frijol Gamuza’, ‘Okinawa’ and ‘Sonoran Yori Muni’ varieties might have begun producing pods. These varieties produced almost no pods over the duration of the trial. They may have been very late-producing varieties. It is also possible that they are day length-sensitive, and the day length was not right for them to produce pods.

Of the top five varieties in Table 1, ECHO’s seed bank is well-supplied with seeds of ‘Reddish Brown’ (an International Institute for Tropical Agriculture accession). We are currently harvesting seeds of ‘V01-020’, but the quality of the seeds is poor. We have very limited quantities of ‘Ejotero’, ‘Tohono O’odham’ and ‘Cerocahui’, but seeds can be purchased from Native Seeds (http://www.nativeseeds.org; search under “black-eyed peas”). ECHO also has seeds of ‘83-060’, ‘Baby Cream’, ‘Zipper Cream’, ‘Bettergrow Blackeye’, and ‘Charleston Blackeye’. Members of our overseas network may request (email: echo@echonet.org) a packet of one or more of these varieties. Those interested in experimenting with these varieties are encouraged to compare them with local varieties. Consider evaluating cowpea varieties for their usefulness as a ground cover as well as for pod production. In our experience, ‘Reddish Brown’ and ’83060’have vigorous vines which quickly cover the ground. Let us know of your results..