Selection ofGongronema latifoliaHybrids Exhibiting Heterosis for Certain Vitamins and Lycopene

Abstract

Heterosis increases the productivity of a crop. Gongronema latifolia has very few and scanty records of heterosis studies and known levels of vitamin contents because it has been harvested from the wild and has a long gestation period of 14-16 months; thus, manual cross-pollination could be difficult in the species. This study was therefore undertaken to determine the levels of certain vitamins and lycopene in genotypes of Gongronema latifolia and to estimate heterosis for the traits across two years. Stem cuttings of five parent plants and their resulting hybrids were established in a field in a randomized complete block design in 2008. Young leaves from these genotypes were harvested and used to determine the levels of vitamins and lycopene and to estimate heterosis in 2009 and 2010. Better parent heterosis (BPH) ranged from −90% to 203% in both years. All vitamins and lycopene, with the exception of Vitamin C, showed positive heterosis in a minimum of five cross combinations. Vitamin E showed the highest BPH of 109% in 2009. Vitamin C had a BPH of 65% in 2010. Vitamin A, on the other hand, had a lower BPH of 52% in 2009. Two hybrids, ENS-8-MBU × AKS-33-EKPENE EDIENE and IMS-20-NJIABA × AKS-33-EKPENE EDIENE, com-plemented each other by exhibiting heterosis for the determined vitamins and lycopene. Selection of two hybrids with a higher level of vitamins and lycopene than in the parents should improve the availability of these nutrients, eventually at a commercial level.

Expression of Heterosis and Heritability in Vegetative Traits of <i>Gongronema latifolia</i>

“…The varied magnitude of BPH for all the vegetative traits in the crosses has also been reported for the chemical components of this species [5] [12]. Reports of high heterozygosity have been reported in vegetatively propagated crops such as plantain [21].…”

“…The BPH estimates were variable across years and parent combinations, hence, the observed G × Y interactions in the expression of the traits. A higher LAP, LB and LL in some cross combinations over the parents indicated the expression of heterosis [5] [17]. The hybrid EBS-49-ISHIAGU x IMS-50-NJIABA with hybrid vigour in LAP, LB and LL could be selected to improve productivity as NLP from the cross will give higher weight with an equal number of leaves for either parent.…”

“…In G. latifolia, heterosis is not yet well understood and a few explanations have been proposed by Agbo and Odo [12] and Agbo et al [5]: 1) genetic distance, and 2) over dominance occurring in one of the parents. The suggested explanations are trait-specific and are likely not a general rule.…”

“…Previous reports have been on expression of heterosis in hybrids of other lines of G. latifolia for phytochemicals [12] and some vitamins and lycopene [5]. The presence of hybrid vigour in the vegetative traits will increase crop productivity to satisfy diverse needs from a given area of production.…”

“…The leaf is the main harvestable part of the plant for human food consumption or for medicine in Nigeria and other subSaharan African countries. The crop has been reported to be nutritionally high in protein, amino acids and vitamins [3]- [5]. G. latifolia traditionally plays a very vital role and in recent times has served as a herbal medicine useful in the management of diabetes mellitus, high blood pressure, and in the treatment of loss of appetite, dysentery, typhoid, worm infections, malaria and stomach ache; moreover, the aqueous and ethanolic extracts of the leaves have anti-inflammatory properties [3] [6]- [8].…”