Breeding and Seed Production of Ornamental Crops (2+1)

Jasmine Breeding

INTRODUCTION
Jasmines are a group of perennial highly domesticated ornamental plants grown for their fragrant flowers. Of 200 species growing wild in tropical and sub tropical world 42 are known to grow in India. However, only 4 of these species are grown commercially in the country. Jasmines have enormous scope as commercial ornamental flower as well as essential oil industry. Efforts for genetic improvement in jasmines have been taken up recently.
IMPORTANT SPECIES
1. Jasminum sambac
Buds and flowers of this species (Arabian jasmine, Tuscan jasmine, bela, mogra) are used for garlands, adorning of hairs, worship and decorations.
2. Jasminum auriculatum
Buds and flowers of this jasmine (Juhi, jui, mullai) are commonly used for garlands, adorning hairs, worship and decoration.
3. Jasminum grandiflorum
This jasmine (French jasmine, chameli, pitchi) is the chief source of jasmine essential oil
4. Jasminum pubescence (Syn J. multiflorum)
This jasmine (kundphul, kundamu, and kundum) is practically non-scented but very attractive. It is one of the hardiest jasmines and least affected by pests and diseases.

Floral Biology

• Flowers of jasmine are hermaphrodite having 2 bilobed anthers. The gynoecium, has one ovule, simple style and bilobed stigma. Ovary is superior, bilocular having axial placentation.
• In jasmine 4 patterns of anthesis have been reported viz. 5 to 6 PM (early), 6 to 7 PM (medium), 7 to 8 Pm (late) and 8 to 10 PM (very late). Similarly three patterns of dehiscence were recorded 3 to 11 PM, 4 to 5 PM and 5 to 6 PM. Period of blooming in jasmine vary from 3 to 4.5 months. Maximum number of flower buds opens from 6 to 7 Pm.
• Floral dimorphism expressing long and short carpel have been reported in Jasminum grandiflorum. Distinct differences in flowering behavior of these two types were observed. The long carpel (pin) type had prolific flowering, whereas short carpel (Thrum) type expressed shy flowering. In Jasminum auriculatum pin and thrum type flowers have been reported. Thrum type plants were reported to be superior to pin type in floral bud length, corolla tube length, and diameter of open flower.

SEED SET AND GERMINATION

• Seed set depends on genotype and environment on the basis of seed setting percentage. In one study at IIHR, Bangalore, jasmines were grouped into 5 groups viz., profuse seed setting type i. e 70 to 80 per cent (J. auriculatum); moderate seed setting type i.e. 5 to 10 per cent (J. calophyllum, J. flexile); poor seed setting type (J. angustifolium, J. grandiflorum, J. savissinum) ; very poor seed setting type i.e. below 1 per cent (J. arborescens, J, rigidum) and nill seed set type (J. humile, J. nitidum, J, officinale and J. pubescens).

OPEN POLLINATED SEEDLING SELECTION

• A high yielding variety of Jasminum auriculatum , ‘Parimullai’ was evolved by TNAU, Coimbatore. It yields 4300 kg flowers compared to 2500 kg obtained in ordinary types. It is resistant to gall mite infestation also.
• In J auriculatum several seedling selections were evaluated at TNAU, Coimbatore. A seedling selection yielded over 8.8 tonnes of flowers/ha and 0.34% concrete, the floral buds possessed short corolla tube and bold bud size. The selection was released as ‘CO1 Mullai’. Based on their distinctive morphological and economic character six clones of J. grandiflorum were identified. Among these, the clone Jg3 Scions of the strain, Lucknow), was promising in flower production (10,144 kg/ha) and concrete recovery (29.42 kg/ha). It was released as 'CO1 Pitchi' by TNAU. At IIHR, Bangalore, by clonal selection a high yielding strain (Pink Pin) of Jasminum grandiflorum has been developed. Its potential flower yield is 10 tonnes per hac and potential recovery of concrete is 35 kg/ha. At IIHR, Bangalore Anon has recently named it as 'Surabhi’. Another strain developed by IIHR, is 'Pink Thrum.' It produces more concrete (0.41 per cent) but is poor in flower yield.
• Narayanaswamy et al. evaluated 18 Jasminum types (4 Cvs. of J. auriculatum and 14 cvs. of J. sambac) to occurrence of rust (Uromyces hobsoni). Leat spot (Cercospora jasminicola) and anthracnose (Colletotrichum sp). Jasminum sambac cv. ‘Eruvatchi', J. calophyllum and J. paniculatum were completely free from the 3 diseases. Jagadish Chandra et al. screened 18 species and 11 varieties of Jasminum against yellow ring mosaic virus. Seven species (J. angustifolium, J. arborescens , J. calophyllum, J. nitidum, J. rigidum, J. sambac and J. suavissimum) expressed 10 to 100 per cent infection. Whereas 5 species (J. auriculatum, J. beesianum and J. grandiflorum L. (Pin and Thrum types) J. officinalis and J. auriculatum did not exhibit the symptom indicating they possess factor for resistance, hence can be used in breeding programme for disease resistance. In this connection it is to mention that jasmine species like J. calophyllum, J. flexile, J. angustifolium and J. rigidum when grown in Coimbatore were found to be tolerant to yellow ring Mosaic but on growing in Bangalore, those were observed to be susceptible. In Jasminum amingay has revealed appreciable tolerance to white fly and red spidermite.

Hybridization

• Genetic improvement in jasmines through hybridization appears to be complicated. The most important barrier is non-fruitfulness is most species and cross combinations. Under natural conditions seed set varies with variety in species. Peak and active flowering occurs during night. Breeder normally face difficulty in emasculation and pollination as styles in some cases are long and fiery delicate, so risk of damaging the stigmatic region is very high The problems are further aggravated by the greater impact of insect interference due to fragrance. It has been observed that very minute insects move up and down the corolla tube thus possibly making the stigma dusted with pollen. Normally jasmine fruit contain only one seed. Growth of seedling is slow. Keeping all the points in view jasmine breeder has to devise suitable breeding technique and method to control the minute insect before emasculation and after pollination, so as to get wide range of variability for different plant characters. There should be bud pollination to avoid insect interference.
• A large number of crosses were attempted at IIHR, Banglore, involving Jasminum arborescence, J. calophylum, J. flexile, J. grandiflorum, J. humile var. wallihianum, J. nitidum and J. rigidum. Most cross combination failed to set seed. Certain combination produced very shriveled seeds. Except from one combination involving the parent J. flexile and J. suavissimum in others there was no germination. Some workers evaluated 18 hybrid progenies of two parental combinations viz., 'Mutant' x 'Parimullai' (A1 to A10) and 'Mutant' X Long point (B1 to B7) for their variability. Higher variability was observed for plant volume and flower yield per plant. B7 and A 1 expressed consistently highest flower yields. Several intervarietal crosses of J grandiflorum were attempted at IIHR Bangalore. Only one combination viz. Seed set selection × Pink Pin yielded 6.8 %, seed set 0 to 3.2 per cent. Hybridization of Jasminum pubescens, with several allied species failed to yield any seedset.

Mutation Breeding
Jasminum species should be subjected to a range of physical and chemical mutagens for creation of large spectrum of variability for the characters of economic importance. Induced variability when followed by cycles of recombination and selection can result in improvement of desirable attributes which otherwise may not respond to selection. Once a desirable mutant is achieved it is easy to multiply it by vegetative propagations. Rao and Krishnan reported a spontaneous mutant with larger flowers in Jasminum auriculatum. On comparison with the source plant, it excelled in length and width of floral bud, length of corolla tube, diameter of open flower, number of petals, length and width of petal and 100 floral buds weight.

• At TNAU, Coimbatore, Chezhiyan et al. reported a variegated mutant Jasminum auriculatum. It was obtained on seed irradiation with 7.5 Krad, 12.5 Krad, 30 Krad and 10 Krad + Ethyl methane sulphonate 2%. The plant flower normally in 12 months. Because of short stature and variegated foliage this mutant has added ornamental value.
• In case of Jasminum grandiflorum, Nambisan et al. reported two induced mutant viz. resistant to Cercospora jasminicola and dwarf. However, both yielded lower concrete percentage. Sensitiveness of J. grandiflorum, cuttings to gamma radiation has been reported by Kumar et al. Softwood cuttings of the variety 'CO1 Pitchi' were subjected to 0.5 to 3 Krad. Rooting declines from 55% in 0.5% in 3 Krad. Similar trends was observed with regard to sprouting of axillary buds. Rooting in-non-treated cuttings was 85%. Devaiah and Srivastava reported that LD50 was close to 2.5 Krad for Jasminum grandiflorum var. Pink Pin' and close to 0.5 Krad for var. 'Pink Thrum', close to 2.5 Krad, for J. flexile, close to 1 Krad for J. calophyllum and 2 Krad for J. sambac. "Gundumalli'. Percentage of rooting, number of roots per cutting, length and thickness of roots decreased with increase in intensity of gamma radiation.

Polyploidy

• Spontaneous triploid in (2n = 39) Jasminum sambac has been reported by Sharma & Sharma , in J. grandiflorum by Murthy & Khanna , in J. ilicifolium by Taylor in J. nitidum by Taylor , in J. primulinum by Krishnaswamy shaman , and in J. autumnale by Sharma and Sharma.
• Spontaneous tetraploidy (2n = 52) have been reported by Dutta in J. calophyllum, by Raman in Jasminum flexile. Triploidy in J. grandiflorum has been found to increase concrete content and there by hold promise by as useful avenue for improvement of this crop. Efforts to induce tetraploidy has been attempted in jasmine. Suppression of polyploidy by diploid growth despite pinching has been a bottleneck in polyploidy programme. Induced tetraploidy in J. grandiflorum did not reveal superiority.