Assessment of Cotton Cultivar Resistance to Cotton Leaf Curl Disease in Multan District

Abstract

In Pakistan, cotton enjoys prominent position in agriculture economy. The cotton is known for a best source of fiber along with natural oil and widely known as a white gold. Cotton is cultivated mostly in Punjab and Sindh provinces of Pakistan while Balochistan is an emerging market for organic cotton cultivation. The cotton production is threatened by Cotton leaf curl disease (CLCuD) caused by begomoviruses exclusively transmitted by whitefly, Bemisia tabaci. The present study was conducted to ascertain the resistance level in cotton cultivars against CLCuD in Multan district. During cotton seasons 2018-19 and 2019-20, a survey was carried out in Multan district covering all four tehsils viz. Multan city, Multan Saddar, Shujabad and Jalapur Pirwala. The resistance level in cotton cultivars were evaluated using CLCuD rating scale followed by diagnostic PCR amplifying the partial coat protein gene sequence. The two cotton varieties IUB-2018 and MNH-992 were rated susceptible during 2018-19 and 2019-20 with mean disease severity index of 38.49% and 35.94%; 47.91% and 47.87% respectively. The seven cotton varieties IUB-2013, IUB2015, MNH-886, BS-15, BS-18, SS-32 and FH-142 were rated susceptible to highly susceptible during 2018-19 and 2019-2020 with a mean severity index of 46.77% and 61.87%; 48.87% and 63.25%; 61.92% and 61%; 58.39% and 67.55%; 60.68% and 67.50%; 51.75% and 49.25%; 48.37% and 50.80 respectively. During the surveyed seasons, absence of resistant, tolerant and moderately tolerant cotton cultivars were observed. The study reflected an urgent need to release new cotton cultivars resistant to CLCuD for a better cotton production.