Low Temperature Germination in Muskmelon is Dominant

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Cucurbit Genetics Cooperative Report 12:50-52 (article 21) 1989

Haim Nelson and Jack E. Staub
ARO, Newe Ya’ar Experiment Station, Israel, and USDA-ARS, Department of Horticulture, Univ. Wisconsin, Madison, WI 53706

Muskmelon seed (Cucumis melo L.), like most domestic cucurbits, requires 17 to 18°C for germination (threshold temperature). At lower temperatures the membrane transfer from the ‘dry’ to the ‘wet’ phase is very slow, resulting in destructive leakage of solutes (H. Nerson, unpublished data). The existence of germplasm with low-temperature germination potential in muskmelon has previously been reported (1, 2). This report provides preliminary information regarding the inheritance of low temperature germination in this species.

The birdsnest inbred line P202, which possesses an ability to germinate at 15°C (2), was crossed with Noy-Yizreel (NY), an indeterminate cultivar which does not germinate at this temperature. The F1‘s were produced in a greenhouse (Winter 1985) and the F2’s in a field nursery (Spring 1985) at Newe Ya’ar Experiment Station (northern Israel). Seeds were kept at 10°±2°C and 45-55% RH for three years before evaluation of germinability. Four replicates of 25 seeds were germinated in 9 cm petri dishes on Whatman No. 2 blotting paper moistened with 4 ml deionized water under optimal (28°C) and low (15°C) temperatures in the dark. In a greenhouse 10, 15 and 50 replicates (10 seeds each) of parents, and reciprocal F1 and F2 progeny, respectively, were sown in 3 liter pots containing a soil : sand : peat (2:1:1) medium for an emergence test. The maximum day and minimum night temperatures ranged between 25 to 32°C and 18 to 21°C, respectively. Germination (radicle length > 3mm) and emergence (cotyledon above soil) were recorded during a 3 week period to determine final percent and rate (mean days germination – MDG, and mean days emergence – MDE).

The preliminary results (Table 1) demonstrate the low-temperature germination in P202 is dominant. It could be hypothesized that more than one dominant gene (perhaps 2) are involved in the expression of this character. This hypothesis is currently being tested using BC1 families. Germination rates in reciprocal F1 progeny indicates that there is a significant maternal effect. Progeny of P2 X P1 matings having NY maternal tissues are slower to germinate than their reciprocals. This effect was essentially eliminated in F2 progeny germination. The maternal effect in the F1 was probably limited to radicle initiation, since there was no significant difference in emergence rate (MDE) at the suboptimal temperature tested.

Table 1. Germination, and emergence percentage and rate of P202 (P1) and NY (P2) muskmelon and their F1 and F2 progeny.

Percent Germination

Mean days to Germinate

Emergence
28°C
15°C
28°C
15°C
Percentage
MDE1
P1 (P202) 100±0 98±2 1.18±0.08 7.06±0.10 91±5 7.32±0.72
P2 (NY) 91±2 2±2 2.86±0.34 – 85±8 9.96±1.14
F1 (P1X P2 94±2 87±8 1.21±0.08 8.34±0.26 85±10 6.71±0.91
F2 (P1X P2) 75±15 82±9 2.67±0.70 13.48±0.58 85±8 7.90±1.19
F2 (P1X P2) 97±2 87±5 1.09±0.06 9.65±0.59 94±3 6.90±0.75
F2 (P2X P1) 98±2 89±3 1.02±0.03 8.48±0.50 96±1 7.01±0.86

Literature Cited

  1. Hutton, M.G. and J.B. Loy. 1987. Association between cold germinability and seedling cold tolerance in muskmelon. Hort Science 22:1131 (Abstr.)
  2. Nerson, H., D.J. Cantliffe, H.S. Paris and Z. Karchi. 1982. Low-temperature germination of birdsnest type muskmelons. HortScience 17:639-640.