Intra-Specific Hybridisation And Performance Evaluation Of Hybrid Lines Of Roselle (Hibiscus Sabdariffa L.)

ABSTRACT Roselle (Hibiscus sabdariffa L.) is an important multi-purpose crop in Ghana and across West Africa, used as a source of food as well as raw material for medicinal and industrial applications. However, due to limited research efforts to gather relevant information on breeding behaviour and inheritance of desirable traits of existing cultivars to enhance yield and nutritional contents, economic potential of the crop has not been fully exploited. The present study was therefore initiated with a broad objective of assessing breeding behaviour and nature of inheritance of selected qualitative and quantitative traits and also variability with respect to agro-morphological characteristics, as well as nutritional composition of leaves and calyces, among 20 local accessions of roselle (Hibiscus sabdariffa L.); comprising 6 accessions of H. sabdariffa var altissima and 14 accessions of H. sabdariffa var sabdariffa. The accessions were collected from three major production regions of Ghana (Northern, Volta and Western). The investigations were carried out at the research fields and laboratories of Biotechnology and Nuclear Agriculture Research Institute (BNARI) from April 2013 to November 2014. All six accessions of var altissima were able to hybridize with one another in both direct and reciprocal cross combinations with high degree of crossability success (30 % to 80 %). On the other hand, cross compatibility among the 14 accessions of var sabdariffa was direction-dependent, and crossability success was low (0.00 % to 43.33 %), as some parents could only be used as males or females. Parental lines A3 and A11 emerged as most compatible male and female respectively. Crossability success was relatively high during early hours of the day but decreased continuously in subsequent hours. Fourteen parental accessions and 25 F1 progenies of var sabdariffa evaluated for 23 agromorphological traits exhibited significant variations in all quantitative traits studied. xvii Clustering pattern based on both qualitative and quantitative traits largely reflected colour and size of calyx. Leaf and calyx traits showed strongest positive association among pairs of quantitative traits investigated. Accessions D2, D3, D4 and D6 exhibited highest general combining ability for major yield traits; days to first flowering, number of fruits per plant, plant height and stem basal diameter, while D2 x D5, D5 x D2, D2 x D4, D6 x D5, D3 x D6 and D6 x D4 emerged as most promising in specific cross combinations following a diallele experiment. Concentrations of the various nutrients were generally higher in calyces compared to the leaves. Except for total titrable acid and vitamin C contents, F1 offspring performed better on all other parameters than their parental accessions and control varieties. Calyces of A11 x A1 and A11 x A13 contained highest protein, ash and pH contents and relatively low moisture as well as highest concentration of K (3284.04±0.01 mg/100 g), Fe (19.45±0.02 mg/100 g) and Ca (1360.70±1.0 mg/100 g), while A4 x A1 recorded highest concentrations of Mg (4.30±0.88 mg/100 g). With regards to the leaf samples, A7 x A12 produced highest values for Ca (1440.20±1.00 mg/100 g) and Fe (15.59±0.01 mg/100 g), while A11 x A2 gave highest Mg (2.72±0.13 mg/100 g) and Na (32.93±1.15 mg/100 g) contents. Similarly leaves of A2 gave highest concentration of K (1641.08±0.01 mg/100 g). These results demonstrate possibility of producing superior hybrids of roselle through artificial cross-pollination. Key recommendations based on these findings include: i) ascertaining specific barriers to crossability between accessions of H. sabdariffa var sabdariffa and H. sabdariffa var altissima to aid transfer of useful traits between them. ii) use of molecular markers to confirm results of morphological characterisation and also to better understand inheritance of qualitative traits. iii) composite breeding to incorporate as many desirable traits as possible into one or two improved (standard) variety/varieties