Relationship between Key Environmental Factors and the Architecture of Fruit Shape and Size in Near-Isogenic Lines of Cucumber ( Cucumis sativus L.)

Fruit shape and size are complex traits influenced by numerous factors, especially genetics and environment factors. To explore the mechanism of fruit shape and size development in cucumber, a pair of near-isogenic lines (NIL) and were used. The fruit length and diameter, cell length and diameter, and related gene expression were measured. Both the fruit length, diameter, and cell length and diameter showed sigmate curves in the two lines. The cell length and diameter were significantly positively correlated with fruit length and diameter both in two lines. The expression of and showed significant positive correlations with fruit length and diameter increment in , and there was no correlation in . Furthermore, there were significant positive correlations between fruit size and thermal effectiveness (TE), as well as between fruit size and photosynthetic active radiation (PAR), both in two lines. Two models using logistic regression were formulated to assess the relationships among fruit length and diameter in and , respectively, based on thermal effectiveness and photosynthetic active radiation (TEP). The coefficient values of the models were 0.977 and 0.976 in , and 0.987 and 0.981 in , respectively. The root mean square error (RMSE) was 12.012 mm and 4.338 mm in , and 5.17 mm and 7.082 mm in , respectively, which illustrated the accurate and efficient of these models. These biologically interpreted parameters will provide precision management for monitoring fruit growth and forecasting the time of harvesting under different temperatures and light conditions.