Evaluation of genotypes of industrially important mints for high productivity of sucker propagules under variable durations of cropping

摘要

Field productivity and quality of suckers formed on six Mentha arvensis cultivars MAS-l, Kalka, Shivalik, Gomti, Himalaya and Kosi, and M. spicata cultivar Neer-Kalka and M. cardiaca cultivar MCAS-2 were compared at different planting times in the summer - winter seasons of the Indo-Gangetic plains agroclimate. Among the genetic resources screened, large differences were observed in the sucker yield by weight, length, and number and nodes borne per sucker. The sucker yield was high at about 2.7 million ha~(-1) and 12000 kg ha~(-1) by weight when the mother plants were planted in the field nursery on 26 August or 12 September. The later plantings reduced the number of suckers formed on mother plants. The plantings of 26 September, 13 October and 25October gave very low yields ranging between 800 and 3797 kg in weight and 340-980 thousand suckers ha~(-1). The largest number of suckers over all the plantings, averaging 1.9 million ha~(-1), were formed by M. arvensis 'Kosi' and M. spicata 'Neer-Kalka'. The suckers of these cultivars shared several properties of efficient propagules, they were long (>=26 cm), with low fresh weight (<=3.7 g), of medium thickness (<=5.5 mm) with a large number of nodes (about 14). Contrastingly, M. arvensis 'MAS 1' yielded only 0.9 million suckers ha~(-1), which were small (length 16 cm, and of weight 2.3 g, thickness 3.8 mm with 11 nodes). The suckers of M. arvensis 'Himalaya' and 'Shivalik' produced 1.3 and 0.99 million suckers ha~(-1), respectively; their suckerswere long (length >=22 cm, weighed 5.3 g and of thickness >=6.8 mm). These observations and cultivar-wise economics of essential oil production showed that the relative profits from mint cultivation were cultivar dependent and varied as widely as +1 to -0.07. M. arvensis 'Kosi' and 'Himalaya' and M. spicata 'Neer-Kalka', respectively, produced 3.9, 2.3 and 3.4 million suckers ha~(-1) from sucker nurseries planted on 26 August and 12 September and proved to be most productive for economic commercial production of menthol- and carvone-rich essential oils, respectively. These genetic resources are identified as most suited to sub-tropical agroclimates for high productivity of suckers and essential oil.