THE year 1992-93 was disastrous for cotton crop because of the severity of the cotton leaf curl virus disease causing large-scale damage to the crop. In the Punjab, over an area of 2.4 million hectares, the lint cotton yield dropped from 849 kg/ha in 1991-92 to 493 to 574 kg/ha.
In the following three years the total consequent losses up to 1994-95 were estimated around 3 million bales valued at about Rs30 billion (Mahabub Ali, 1997). It is still a major threat to our economy. This prompted the government to pay an urgent attention for the preventive measures against this disease and to initiate research to deal with this serious problem. Consequently, breeders started developing resistant varieties, as it is perceived to be the only way to manage this menace which could guaranty high yields even under the prevalence of disease epidemic .
During October 1996, while surveying the cotton fields scientists of Central Cotton Research Institute (CCRI), Sakrand, observed the attack of cotton leaf curl virus (clcv) near Obaoro of Ghotki district in upper Sindh, soon after, these scientists observed this disease in Khairpur district also with minor intensity. Due to fear of spread of this disease in the whole of Sindh, plant breeding section of CCRI, started transferring clcv resistant genes from identified exotic as well as local resistant cultivars in agronomically better varieties and advance strains of this Institute. Consequently, new clcv resistant strains (CRIS-460 through CRIS-471) have been developed. These strains are being tested in yield comparison trials against prevailing commercial checks. Among these strains, CRIS-467 has shown very good performance in preliminary yield trials and now this strain is being tested for second year in national coordinated varietal (NCVT), the final stage of variety test.
The NCVTS are laid out/planned every year by the Director of Research, Pakistan Central Cotton Committee, Karachi, at approximately 22 locations of the country. These trials are the final stage of variety test no cotton variety is released by the concerned provincial seed council until and unless the variety has not completed minimum of two years of experimentation in these trials. The objective of these trials is to test the yield as well as adaptability performance of candidate cotton varieties developed by the different breeders of Pakistan in different ecological zones of the country.
The candidate varieties are coded (VI, V2, V#, and so on) by the Director of Research, PCCC, Karachi, and seed is sent to different testing centres for sowing in randomized complete block design replicated four times as directed by the authority responsible.
CRIS-467 which will be the first CLCV resistant variety of Sindh was also included in these trials during 2000-2001 cotton season.
CRIS-467 will now complete its second year during this season (2001-2002) in NCVT and hopefully at the end of this season it will maintain its superiority in whole of the country and will be released as the first CLCV resistant variety of Sindh.