Sources of resistance in Varh Karela (Momordica balsamina L.) to root knot nematode
Momordica balsamina is commonly known as Varh Karela. The plant has bright green leaves and striking orange to red spindle shaped ripped fruits. It is indigenous to tropical Africa, Asia and India. Root knot nematode is one of the important pest of bitter-gourd and is reported to cause 38 to 48.2% yield losses. In the present study, screening of 14 Var Karela lines viz (MB -3, MB-4, MB-5, MB-6, MB-8, MB-10, MB-11, MB-12, MB-13, MB-14, MB -15, MB-16, MB-30 and MB-35) was done to find the source of resistance as most of the cultivated varieties of bitter-gourd are susceptible to root knot nematode. The screening was carried out under field and the resistance was further confirmed under sick plot conditions. Under field conditions all the cultivars were found free from root galls whereas the Punjab - 14 (cultivated check) was found heavily galled. For confirmation of resistance, the seeds of all the entries along with susceptible check (Punjab -14) were sown in plug trays and transplanted in the sick plot having initial root knot nematode population of 360 2nd stage juveniles per 250cc soil sample. After every two lines of Varh Karela one line of Punjab -14 (susceptible check) was transplanted so as to access the pathogenicity of the nematode. Sixty days after transplanting plants were uprooted from all the entries and the roots were graded on 0–5 scale based on number of galls/root system. In sick plot screening, out of 14 varah karela lines, six genotypes MB -3, MB-4, MB-5, MB-11, MB-13, and MB-16 were found resistant to root knot nematode with average root gall index ranging from (0.1 to 1.0), whereas the other six lines viz., MB-6, MB-10, MB-14, MB-15, MB-30 and MB-35 were moderately resistant with average root gall index of 1.1 to 2.0. Hence, the lines showing resistance for root knot nematode can be further exploited in the resistance breeding programme.