Source: Spices Board of India.
QTY in metric tons, VALUE in lakhs (about 2.000 US$).
The area under production gradually increased. It gained momentum with a price spurt during 2001–2002, probably because of severe crop losses due to a cyclone in Madagascar. Because of the decline in market price of natural vanillin since 2004–2005 coupled with unmanageable disease occurrence, the enthusiasm in growing vanilla has declined dramatically among farmers.
Crop Improvement of Vanilla
Crop improvement of vanilla is in progress in India at the Indian Cardamom Research Institute (ICRI), Spices Board, P.O. Kailasanadu, Idukki, Kerala; Indian Institute of Spices Research (IISR), P.O. Marikunnu, Calicut, Kerala, Kerala Agricultural University, and other institutions. These institutes maintain a good germplasm collection of vanilla as well. A minimum descriptor for vanilla is developed for characterizing the germplasm (Kuruvilla et al., 2000).
Species Diversity
V. planifolia G. Jackson is the cultivated vanilla species in India. In addition to this, the other vanilla native species available in India are Vanilla pilifera Holtt., Vanilla andamanica Rolfe., Vanilla aphylla Blume, Vanilla walkeriae Wight, and Vanilla wightiana Lindl. The Tahitian vanilla (Vanilla tahitensis J.W. Moore) is also conserved in India.
Breeding Behavior
The floral biology of V. planifolia is adapted to outcrossing, and hand pollination is resorted to pod set in India, as the natural pollinators are absent in the country (Sasikumar et al., 1992). No self-incompatibility or natural crossing is reported in V. planifolia from India as observed in Reunion Islands or Mexico (Bory et al., 2008a). However, in V. wightiana, natural fruit setting is reported (Rao et al., 1994). Stray fruit set under natural conditions is also seen in V. aphylla.
Reproductive biology of V. planifolia such as time of pollination, stigma receptivity, and effect of pollen load on the size of the beans were studied (Shadakshari et al., 1996; Bhat and Sudarshan, 1998, 2000). These authors reported that the ideal time for pollination is from 6 a.m. to 1 p.m., and stigma receptivity is up to 24 h. They also observed that complete transfer of pollen results in maximum fruit growth.
Inflorescence initiation in vanilla occurs in late January or early February and the flower opens from mid-February to April–May. Pollination is carried out manually as and when the flower opens and the process is continued for at least 40–60 days. The beans develop quickly in the initial stages and attain their full size within a period of 5–6 weeks under favorable conditions and thereafter slow down. The rate of elongation of beans is maximum during the first 30 days after fertilization (Kuruvilla et al., 1996).
The reproductive mode of V. planifolia needs to be studied, thoroughly looking into the rate of outcrossing, self/cross incompatibility, and autogamy.
Cultivar Diversity
Although vanilla was introduced to India about 200 years ago, the present-day gene-pool in India is derived from this original introduction. Being perpetually propagated vegetatively from these original germplass, a wide genetic base in the primary gene pool of vanilla is very unlikely (Sasikumar, 2004), akin to the situation in some other vanilla-producing countries (Soto Arenas, 1999; Lubinsky, 2003; Bory et al., 2008b). There is no authentic record of any subsequent introductions to the country.
Over the years of domestication and selection by farmers, some new variants (subcultivars) have been recognized in Mexico and Reunion Islands, but no such variants are reported from India, barring a variegated mutant “Marginata” (Minoo et al., 2006a, 2008b) and some accessions with branched inflorescence and varied leaf size. Somatic crossing over (Nair and Ravindran, 1994) reported in V. planifolia can give rise to new variation, apart from mutation, sexual recombination, or epi-genetic variation.
Genetic diversity analysis of V. planifolia accession in India will be worth attempting as it may help to confirm the existence of genetic variability, if any, in the germ-plasm and help in the breeding program.
Interspecific Hybridization
The variation that exists among the cultivated species of vanilla or even in some related species can be combined to produce new types through hybridization. The secondary gene pool may contain useful genes for self-pollination, root rot and virus resistance, larger fruits, reduced photosensitivity, better aroma profile, and pod indehiscence for incorporating into the cultivated vanilla. Because of incompatibility between some vanilla species, breeders may attempt to raise the progenies of interspecific crosses through in vitro seed culture. Interspecific hybrids between V. planifolia × V. aphylla (Minoo et al., 2006b, 2008a) and V. planifolia × V. wightiana (Rao et al., 1992b) are reported from India.
The xenia/metaxenia aspects too can be looked into inter alia as it is observed that pollen of some vanilla species have a positive effect on the pod size of V. planifolia (B. Sasikumar, personal observation).
Agronomy
Climate and Soil
Vanilla being a climbing orchid, conditions favorable for its vegetative growth as well as flowering are to be provided for the commercial production of vanilla beans. The plant requires warm and moist conditions of humid tropics for proper growth and sustainable production. It thrives well between 10°N and 20°S latitudes, having well-distributed moderate rainfall between 150 cm and 300 cm. The crop tolerates a wide range of temperature, but ideally, the mean minimum temperature during winter months should not go below 12°C and should not exceed 35°C during summer, and the optimum temperature range being of 25°–32°C with a mean relative humidity of 80%. The plant does not tolerate any prolonged duration of drought or water-logging, and exposure to hot sun or to strong winds.