TOLERANCE RESPONSE OF MUSKMELON RECOMBINANT INBRED LINES AGAINST SALINITY

Abstract

Muskmelon is the most important vegetable crop of arid and semi-arid regions and salinity is the most prevailing abiotic stress in such areas. Therefore, the present study was conducted to determine salt tolerance of twenty muskmelon recombinant inbred lines (RILs) based on determining of seeds germination rate and percentage in laboratory experiment and measuring of some morphological and horticultural attributes for them in pots experiment under netted house at Horticultural Research InstituteAgricultural Research Centre, Egypt during 2016 and 2017 early summer seasons. These RILs were exposed to four different levels of sodium chloride (NaCl) viz., 0 mM, 50 mM, 75 mM and 100 mM after 15 days from seed sowing. The findings confirmed that the salinity tolerance of any genotype was increased as the reduction or increment rate for this genotype compared to control reduced and vice versa. So, the muskmelon RILs 305 and 307 showed salinity tolerance till 50 mM NaCl and RIL 309 had salinity tolerance till 75 mM NaCl, but none of RILs had salinity tolerance at 100 mM NaCl in all measured traits. Based on these two salinity experiments, these three muskmelon RILs were selected as salt tolerant and were made all the combinations of crosses among them in one direction to produce three F1 hybrids that were grown under greenhouse at Kaha Vegetable Research Farm (KVRF), Kalubia during 2017 late summer season. These three F1s beside their parents and hybrid Gal 23 (used as control) were sown in the two open fields using drip irrigation system at Sadat city, Menofia Governorate, one of them was irrigated with groundwater 955 ppm salinity (used as control) and the other field was irrigated with groundwater 2760 ppm salinity (used as a field dose for salinity tolerance evaluation) during 2018 early summer season. The results of these hybrids evaluation under salinity stress compared to control field showed that the hybrid RIL 309 × RIL 307 had high level of salinity tolerance, hybrid RIL 309 × RIL 305 had moderate level of salinity tolerance and hybrid RIL 307 × RIL 305 had low level of salinity tolerance. Finally, all measured traits didn't differ under salinity stress compared to control field in the hybrid RIL 309 × RIL 307. This indicated that the hybrid RIL 309 × RIL 307 could be used under salinity stress condition.