eChapter Name: Marigold
9789390591831
eBook Name: FLOWER PRODUCTION & GARDENING
by B.S. Beniwal, Sonu Kumari Sheoran
Marigold (Tagetes spp.) is an important annual flower crop; native to Central and South America especially Mexico and belongs to family Asteraceae (Compositae). It is commonly known as “Gainda” in India and also called as “Friendship Flower” in United States of America. Loose flowers of marigold are in great demand throughout the year. It is commercially grown in tropical and subtropical regions of India owing to its ease in cultivation, hardy nature, wider adaptability and year round availability of single, semi-double and double flowers of vibrant colours. Marigold is grown over an area of about 66.09 thousand hectares with production of 603.18 thousand MT loose flowers in India. Major states involved in loose flower production of marigold are Karnataka, Madhya Pradesh, Gujarat, Andhra Pradesh, West Bengal, Maharashtra, Haryana and Chhattisgarh. In India, Assam is the only state, which produces marigold for both cut as well as loose flower purpose on an area of about 0.61 thousand hectare (Anonymous, 2016a).
Marigold is a cross-pollinated flower crop and it is pollinated by insects (Kaneko et al., 1990). It bears terminal and solitary inflorescence, known as head or capitulum, which possesses long and hollow peduncle with swollen apex and campanulate involucres (Setshogo, 2005). Capitulum consists of peripheral ray florets and central disc florets. Ray florets are pistillate, ligulate, sessile, epigynous and zygomorphic, whereas, disc florets are bisexual, tubular, sessile, epigynous and actinomorphic (Subrahmanyam, 1996 & Setshogo, 2005).
African marigold (Tagetes erecta L.) is a diploid species (2n = 2x = 24), while, French marigold (Tagetes patula L.) is a tetraploid species (2n = 4x = 48) with basic chromosome no. of x = 12 as revealed by breeding work of various researchers (Towner, 1961, Chen and Lin, 1981, Chen and Lin, 1982, Serrato-Cruz et al. 2000, Zhang et al., 2011). Tagetes erecta and Tagetes tenuifolia are diploid species, whereas, Tagetes patula, Tagetes minuta, Tagetes biflora and Tagetes remotiflora species are tetraploid in nature (De, 2017). On the basis of floral morphology; three different types of male sterile systems i.e. apetaloid, petaloid and gynomonoecious types was observed in African marigold (Prakash et al., 2016). Out of these, apetalous male sterility (femina type) is more reliable and preferred over petalous male sterility because later is more prone to break down (Goldsmith, 1968 & Janakiram, 2004). Apetaloid male sterility was controlled by single recessive gene (Prakash et al., 2016). A monogenic recessive male sterile apetalous mutant was detected from T. erecta population by Khoshoo (1979). Cyto-genetic male sterility is also found in marigold (De, 2017). Petaloid and gynomonoecious male sterile systems were controlled by cytoplasmic inheritance (Prakash et al., 2016). In marigold, cytoplasmic genetic male sterile lines were also developed for commercial production of Fl sterile hybrids (Pratibha et al., 2000).
