Studies On The Identification And Selection In The Germplasm Resources Of Lettuce (Lactuca Sativa L.)

Developing new varieties of lettuce(Lactuca Sativa L.), to satisfy the demand of production. Identification and selection of germplasm resources and breeding is a basic work. The experiment used 55 germplasm materials, morphological characteristics and biological characteristics, quality and resistance of these germplasm materials were be investigated and studyed and selected excellent properties germplasm resources. Results are as follows:(1) Coefficient variation of lettuce existed difference, the lowes is only 8.82%, while the highest is 98.85%, the main quantity character of leaf lettuce have rich heredity multiplicity, it contained very big potential in the idioplasm variation and the innovation aspect. Head lettuce's leaf characters and the output characters have rich genetic information and choice of potential, plant height, plant breadth, Number of head-forming leaves are stability.(2) Comprehensive various heat resistance identification and physiological and biochemical properties obtains: The heat-resistance leaf varieties are S4, S24, S19, W9, W15, The heat-sensitive leaf varieties are S2, S6, S7, S10, S11; The heat-resistance head varieties are: S11, J18, J20, The heat-sensitive head varieties are J1, J2, J7; the 7 semi-head varieties have the extremely heat-risistance and commercial.(3) In the low temperature, the quantity of growing and the rate of increasing may applied in cold resistance identification. The varieties S24, J14, J15, J12, W15, W12, W9 are grown higher in the low temperature, adapt the cold condition. But the varieties S25, J16, S21, S20 are grown slowly, they do not suit to cultivate in the cold condition ; the head lettuce varieties J6, J11, J2 , J17not only have the low rate of increasing ,but also heading loosely, the variety J1 cannot normally heading; contrary, the rate of increasing of the varieties J8, J9, J18, J19, J20 are all bigger than 25g/d in later period, they are the cold-resistance head varieties ; semi-head varieties have the good cold-risistance.(4) The disease resistance leaf lettuce varieties are S1,S15,S22,S25,W9,W12,W16,J4,J12,J14,J15,J16 .The disease resistance head lettuce varieties were J6,J8,J11,J20,J1,J18,W19, W1,W3,W4.(5) All the 34 leaf lettuce varieties collected seeds, while only seven head lettuce varieties collected seeds, because the head lettuce in head formation stage require the suitable temperature and different varieties exist great difference. for the head lettuce is strict in collecting method and time. seed Collecting is very difficult, Therefore, the seed Collecting method of head lettuce still need to continue study.