Effects of ridge direction on growth and yield of tomato in solar greenhouse with diffuse film

Abstract: In the solar greenhouse, which was covered by ordinary film with small haze, the planting pattern of south-north ridge was used in common. In east-west ridge, there could be the shadow on the north side produced by south side of planting line, which caused some problems including that the distribution of light would be uneven, and the growth would be impacted. However, due to the current labor shortage and low production efficiency, there is urgent need for small agricultural machinery used in the solar greenhouse, while the shorter north-south planting ridge has limited the use of agricultural machinery and operation efficiency. Tomato ("Gem 1") plants, were planted on September 20, 2016 in glasshouse. The length of test greenhouse was 60 m, and the span was 8 m, which was located in Fengnan District, Tangshan City, Hebei Province. The greenhouse was covered by film with 55 % haze and 85% light transmittance. This study aimed to analyze the effects of 2 planting ridges on tomato growth and yield. The photoperiod, and physiological and morphological indices of different height of canopy were studied with 2 kinds of tomatoes grown in north-south and east-west ridge, respectively, and the photosynthetic rate and yield were compared. The hypothesis is there exists the feasibility of using the east-west ridge in the scattered light solar greenhouse. To test this hypothesis, a study was conducted in glasshouses covered with scattering glass, converting a portion of the direct solar light into scattered light with different degrees of scattering, without affecting light transmission. Tomato was used in this study. The results showed that in the diffuse light environment, the tomatoes grown in the east-west ridge were the same as those in the north-south ridge, and the light intensity in the canopy increased with the height. And there was no significant difference in the light accumulation between the ridges of the east-west and north-south. In addition, the leaf area index (LAI) of tomato was 4.34 and 4.29 respectively, the chlorophyll SPAD (soil plant analysis development) content was 42.7±1.0 and 43.1±0.6 respectively for the east-west and north-south planting pattern, and the difference did not reach the significant level. In the east-west ridge, the distribution of leaves inclination angle was the same as that in the south-north ridge, concentrated between 60° and 80°. And the net photosynthetic rates of the leaves were 12.8 and 12.4 μmol/(m2·s), and the difference was not significant; from December 2016 to February 2017, the yield of tomato of east-west ridge was 2 537.6 kg, and the other was 2 421.1 kg, and the difference was not significant. It could be seen that there was no significant difference on the growth and yield of tomatoes between the east-west and south-north ridges in the solar greenhouse covered by film with 55% haze. Therefore, the effects of 2 kinds of planting ridges on the growth and yield of tomato in diffuse light in the Chinese solar greenhouse were not significant. Thus, in the solar greenhouse with diffuse light environment, we can not only use the east-west ridge instead of the north-south ridge for tomato planting pattern, but also use the east-west farming pattern for agricultural operation.