Some Morphological Parameters Involving the Mechanism of Early Yield in Cucumber

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Cucurbit Genetics Cooperative Report 17:24-26 (article 7) 1994

Meng Zhang and Hongwen Cui
Department of Horticulture, Northwestern Agricultural University, YangLing, Shaanxi 712100, P.R. China

With the development of a market economy in China, increased attention is now being given to early maturity breeding. In the past, only a few traits were selected during hybrid development. There was little attention paid to the selection of multiple traits. theoretical studies in tandem and multiple trait selection have been proposed but not well documented. Traits related to early yield were regarded as being directly correlated in cucumber and other crops (Yujhai, 1985; Li and Li, 1985). However, evaluations were subjective in nature. Canonical correlation analysis was used in this study to identify character groups which affect early yield. The aim of this paper is to identify components of early yield in cucumber.

Method. An experiment was conducted at the Horticulture Station of the Northwestern Agricultural University. twenty-four varieties and inbreds were evaluated in a randomized block design with 3 replications. Ten plants of each plot were randomly chosen to evaluate quantitative traits during the early growth period. The traits were divided into four groups according to biological significance. These groups include: 1)early yield component (YC) = fruit length (YC1), number of harvested fruits per plant(YC2 ), and fruit weight (YC3); 2) morphological traits (MT) = the node position of the first pistillate flower (MT1), pistillate flower density (main vine) (MT2), number of pistillate flower (main vine) (MT3), and number of staminate flowers (main vine) (MT4 ); 3) growth period factor (PF) = the days from sowing to the fist pistillate flowering plant in the population (PF1), the days from sowing to pistillate flowering of 50% of the plants (PF2 ), the days from sowing to first staminate flowering plant in the population (PF3 ), the days from sowing to staminate flowering of 50% of the plants (PF4); and, 4) yield physiological basis (PB) = leaf area per plant (PB1) and leaf number per plant (PB2 ). A genotype correlation matrix was used for canonical correlation analysis. These correlation coefficients were tested by the Bartlett method.

Results. The results (Table 1) show that the canonical correlation coefficient of early yield with yield components (yield physiological basis and trait groups) were extremely significant. Data indicated that these two trait groups directly affected early yield Ii.e., more than 97% of the total genetic correlation). This proved that yield components have a direct relationship to early yield. Although the physiological basis of yield correlated significantly with early yield, the coefficient accounted for only 48.6 of total genetic correlation.

The formation of the first canonical variable (FFCV) of yield components (TC) with morphological traits (MT) indicated that they were affected mainly by the action of pistillate flower density (MT2) and the number of pistillate flowers (MT3) to the number of harvested fruit (YC3).

Table 1. Canonical correlation analysis between early yield and character groups in cucumber.

Character group

Canonical correlation coefficient¹

R²

X²

d.f.

Significant
YC 0.98639** 0.97297 59.57437 3 0.000
MT 0.56015 0.31377 6.02460 4 0.197
PF 0.52194 0.27242 5.08362 4 0.278
PB 0.69743** 0.48641 11.32761 2 0.003
YC + PB 0.98731** 0.97478 57.04573 5 0.000
YC + MT + PF + PB 0.99732** 0.99465 60.13021 13 0.000

¹*p = 0.05, **p = 0.01

Table 2. Canonical correlation analysis between early character groups

First group variable

Second group variable

Canonical correlation coefficient¹

X²

d.f

Significance

R²

Generalized correlation coefficient
YC MT λ1 =0.83628* 21.20462 12 0.047 0.69936 p = 0.41911
λ2 =0.38116 3.17704 6 0.785 0.785
λ3 =0.23096 0.82230 2 0.663 0.-5334
YC PF λ1 = 0.85349* 23.38360 12 0.025 0.72845 p = 0.38519
λ2 = 0.45633 3.82895 6 0.700 0.20824
λ3 = 0.14674 0.32650 2 0.849 0.02153
YC PB λ2 = 0.90294** 28.08585 6 0.000 0.95023 p = 0.47830
λ2 = 0.25336 1.06147 2 0.588 0.06419
MT PF λ1 = 0.088451* 31.04834 16 0.013 0.78236 p = 0.34480
λ2 = 0.60495 8.93689 9 0.443 0.36596
λ3 = 0.37992 2.32996 4 0.675 0.14434
λ4 = 0.06927 0.06974 1 0.792 0.00480
MT PB λ1 = 0.55136 6.59391 8 0.581 0.30400 p = 0.36911
λ2 = 0.24711 0.97664 3 0.807 0.06107
PF PB λ1 = 0.54710 7.10821 8 0.525 0.29931 p = 41361
λ2 = 0.31270 1.59492 3 0.661 0.09773

¹ *p = 0.05, **p = 0.01

FFCV of yield components (YC) with growth period factors (PF) showed that moving up the time of pistillate flowering (PF1, PF2) would result in an increase in the number of fruits and lowering of fruit weight. FFCV of morphological traits (MT) with growth and period factors (PF) showed that postponing the time of pistillate flowering and moving up the time of staminate flowering would increase the node position of first pistillate flower and increase the number of staminate flowers.

Discussion.It is not certain that all characters related to early yield affect early yield directly. Some of the characters will affect early yield indirectly through the others. If one considers that all characters which affect early yield directly, one can find the important characters which directly affect the early yield. The canonical correlation analysis of characters lays a foundation for the study of early yield mechanisms. The correlation of canonical variances is caused by the linear correlation of characters. There may be a more complicated linear correlation in the character groupings generalized in the correlation among traits.

Literature Cited

  1. Junti D., G. Shu and L. Teuber. 1990. Generalized genetic parameters of multiple traits. Acta Genetic Sinica 17:161-167.
  2. Li, J. and P. Li. 1985. Correlation and path analysis agronomic characters affecting yield in tomato. J. Northeastern Agr. College. 2:59-64.
  3. Qixin, S. and W. Jinlong. 1987. Application of canonical analysis in crop breeding. J. Bejing Agr. Univ. 13:131-139.
  4. Yuhai, W. 1985. Path analysis of main agronomic characters and yield in cucumber. J, Northeastern Agr. College 2:53-58.