Cucurbit Genetics Cooperative Report 19:2729 (article 10) 1996
The Evaluation of Cold Tolerance in Chinese Cucumber Varieties
Zhongli Ji, Huanwen Meng and Hongwen Cui
Northwestern Agricultural University, Yangling, Shaanxi, 712100, P.R. China
Introduction. The northern part of China is in the temperate growing zone. The cold monsoons of the Northwest are responsible for a longer cold season in China than in other countries of similar latitude. As a result, vegetable production is unfavorable during this season. However, microclimates can be established within greenhouses constructed of plastic, which allow for favorable vegetable production at this time of year. This important horticultural practice is used for the breeding and production of cucumber. The paper examines heat sources used in such greenhouses and their efficiency of operation.
Materials and Methods. Seven cucumber varieties (BG3, BG5, ED6, ED10, FC15, FC17, and ME18) from the breeding program at Northwestern Agricultural University, P.R. China, were evaluated. DH23 cucumber was used as a check variety in the field plot experiments described herein. Experiments were designed such that varieties were arranged in a randomized complete block design with 3 replications, and planttworows in plastic greenhouses from February to June, 1995. Thirty plants were examined in each replication on 4.4m^{2} centers. Air temperature was sampled at a height of 1.5m at the center of the greenhouse and at a given point 1.5m height outside the greenhouse. The air temperature sampling times were 8L00, 14:00, and 20:00 HRS., Peking time. The variables (X_{N} ) recorded were: X = {X_{1} ,X_{2}, X_{3} }; where X = sum for all cucumber varieties examined, X_{1} = total fruit yield, X_{2} = cumulative temperature 10 C from February to June 1995 inside plastic greenhouse and X_{3} = disease resistance of the cucumber varieties (% of undamaged control). The matrix (A) of coefficients of the variables assessed was: A = [0.5, 0.3, 0.2]; where A = matrix of coefficients of the variables assessed; 0.5  coefficient of X_{1}, 0.3 = coefficient of X_{2} , and 0.2 coefficient of X_{3} . Fruit grades (Y_{N} ) of varieties were designated as: Y = [Y_{1}, Y_{2} , Y_{3} }; Y = sum for all cucumber grades assessed, Y_{1} = grades of unimproved (acceptable) varieties examined, Y_{2} = grades of improved varieties examined and Y_{3} = grades of inferior varieties examined.
The operational equation used for X_{1} and X_{2} was:

1 
^{x} 1,2> a_{1} 
u (X_{1} X_{2}) = 
X1a_{2}
a_{1}a_{2} 
a_{1} > x_{1,2} > a_{2} 

0 
a_{2} > x_{1,2} 
where u(x_{1} x_{2} ) = the functional value of the x_{1} and x_{2} , a_{1} = the lower limit of the fruit grades of acceptable varieties, and a_{2} = the upper limit of the fruit grades of inferior varieties. The operational equation used for disease resistance of the cucumber varieties was:
where u(X_{3} ) = the functional value of X_{3} , X_{i} = observation date, X_{max} = the maximal value of the observation date and X_{min} = minimal value of the observation date.
Results and Discussion. Air Temperature. The daily mean air temperature and the cumulative temperature of 10 C were higher inside than outside the plastic greenhouse. The monthly mean air temperature in March was 6.9 C higher inside the greenhouse than outside. The monthly mean air temperature in April was 5.5 C higher inside than outside the greenhouse. The cumulative temperature 10 C in March was 18.6 C higher inside the greenhouse than outside the greenhouse in April (Table 1).
Resistance to Cold Stress. A table of differential criterion was constructed from the observational data and experiences of horticultural experts (Table 2).
Grade Evaluation. Values obtained from equations 1 and 2 allowed for the computation of functional values for total yield of cucumber in each experiment, cumulative temperature 10C, disease resistance ratings, and the functional values of grade matrixes. The results are as follows:
Month 
Mean air temperature 
Cumulative temperature of >10C 



Inside 
Outside 
Inside 
Outside 
March 
14.6 
7.7 
426.6 
0 
April 
19.1 
13.6 
574.3 
408.0 
May 17 
21.5 
16.5 
150.3 
115.1 
Table 2. Differential criterion used for classification of cucumber varieties.
Factors 
Acceptable varieties (Y_{1}) 
Improved varieties (Y_{2}) 
Inferior varieties (Y_{3}) 
Total output (X_{1} ) 
>0.90 
0.700.89 
,0.70 
>10C (X_{2} ) 
>0.90 
0.750.89 
<0.75 
Disease resistance 
>0.95 
0.800.94 
<0.80 
^{1}Cumulative temperature
Table 3. Matrixes used in the calculation of fruit grade evaluation of the cucumber varieties examined.


Fruit Grade Components 
Results of Evaluation 
Code name of cucumber varieties 
Matrixes 
Y^{1} 
Y^{2} 
Y^{3} 
BG3 
B_{3}= 
0.6250 
0.3750 
0 
good seed 
BG5 
B_{5}= 
0.6240 
0.4412 
0.2941 
intermediate seed 
ED6 
B_{6}= 
0.3809 
0.5714 
0.477 
intermediate seed 
ED10 
B_{10}= 
0.2000 
0.3000 
0.5000 
bad seed 
FC15 
B_{15}= 
20.6250 
0.3750 
0 
good seed 
FC17 
B_{17}= 
0.2124 
0.2567 
0.5310 
bad seed 
ME18 
B_{18}= 
0.29140 
0.4412 
0.2647 
intermediate seed 
DH23(CK) 
B_{23}= 
0.4414 

0.2941 
good seed 
BG3 R_{3} = 
Y_{1} 
Y_{2} 
Y_{3} 
X_{1}
X_{2}
X_{3} 
1 
0 
0 
0,6667 
0.3333 
0 
1 
0 
0 
ED10 R_{10 } = 
y1 
y2 
y3 
X_{1}
X_{2}
X_{3} 
0 
0 
1 
0 
0.3333 
0.6667 
0.3333 
0.6667 
0 
BG R_{5} = 
0 
0.6667 
0.3333 
X_{1}
X_{2}
X_{3} 
0 
0.3333 
0.6667 
1 
0 
0 
FC15 R._{15} 
1 
0 
0 

0.6667 
0.3333 
0 
1 
0 
0 
ED6 R_{6} = 
0.3333 
0.6667 
0 

0.3083 
0.6500 
0.0417 
0.8333 
0.1667 
0 
FC17 R_{17} = 
0 
0 
1 

0.1333 
0.2417 
0.06250 
0.3333 
0.6667 
0 
ME18 R_{18} = 
0.3333 
0.6667 
0 

0.2000 
0.2500 
0.2500 
1 
0 
0 
DH23 R_{23} = 
0.6667 
0 
0.3333 

0.3333 
0.6667 
0 
1 
0 
0 
Composite operations (B) for matrix A and matrix R are: B = AOR. Data resulted in the establishment of matrix B which is a comprehensive evaluation for the cucumber varieties. According to Umax, the data resulted in the definition of classes for the cucumber varieties examined (Table 3).
The cold winter monsoon in northern China produces lower winter temperatures than in other countries of identical latitude. For example, latitude is greater in Cologne, Germany (50
˚ 56'N) than in Harbin, China (45
˚ 45'N) but the mean monthly temperatures in December to February are 18.8  21.8 C more in Cologne than in Harbin, China. While the mean air temperature in January is 1.0C in Xi'an, China (34'15'N) and 3.7C in Tokyo, Japan (35
˚ 41'N), the mean air temperature in February is 2.1 C in Xi'an and 4.3 C in Tokyo. Moreover, there are lower air temperatures in Xi'an than in Tokyo. The winter climate of China allows plastic greenhouses to accumulate solar energy which increase inside ambient temperatures. This microclimate is beneficial for vegetable growth.
Literature Cited
 Staub, J. 1995. Problems associated with map construction and the use of molecular markers in plant improvement In: Lester, G.E. and J.R. Dunlap, eds. Proceedings Cucurbitaceae ';94: Evaluation and enhancement of cucurbit germplasm. p. 8691.