Estimation of chlorophyll content in pepper leaves using spectral transmittance red-edge parameters

The objective of this work was to monitor the growth status of pepper and provide precise guidance on fertilization through non-destructive detection methods for chlorophyll content based on spectral transmittance.The analysis of the narrower red-edge spectral region(680-760 nm)reduced the requirements for light sources and light detection sensors,and provided a simpler and more accurate method of data acquisition for the process of developing instruments for estimating chlorophyll content in leaves.The red-edge region of spectral transmittance was demonstrated to be closely related to chlorophyll content.Regression models for estimating chlorophyll content with seven different methods were developed using the four red-edge parameters extracted from the red-edge region.The problems of multicollinearity of red-edge parameters and errors in model coefficients were solved by the ridge regression method in the process of building a multivariate regression model.The results indicated that the ridge regression method reduces the errors of the model coefficients and constant terms while improving the detection accuracy,thus the ridge regression model could estimate the leaf chlorophyll content more accurately and repeatedly.

Two-stage seedling cultivation method for sweet peppers combining closed plant factory and solar greenhouse

This study introduced a two-stage cultivation method for sweet pepper seedlings, integrating the strengths of a closed plant factory and solar greenhouse, to mitigate the environmental constraints in Northeast China during the early spring season. In the first stage, seedlings were cultivated in a closed plant factory, followed by a second stage in a solar greenhouse. Four treatments- T1 (9 and 36 d), T2 (12 and 33 d), T3 (15 and 30 d), and T4 (18 and 27 d) - were designed for the first and second stages, respectively, with solar greenhouse-only approach serving as the control (CK). The findings reveal that the two-stage methodology significantly outperformed the control across multiple metrics, including seedling health index, chlorophyll content, photosynthetic capacity, yield, etc. Specifically, T3 emerged as optimal, boosting the health index by 38.59%, elevating chlorophyll content by 39.61%, increasing net photosynthesis by 34.61%, and augmenting yield per plant by 40.67%. Additionally, T3 expedited the time to harvest by 25 d compared to the control. Although the seedling cost for T3 was 0.12 RMB yuan higher, the benefits offset the additional investment. In conclusion, the two-stage cultivation method effectively leverages the advantages of both closed-plant factories and solar greenhouses, resulting in superior seedling quality compared to using only solar greenhouses. It offers a practical and economically viable solution for enhancing the quality and yield of sweet pepper seedlings, thus contributing to the progress in the field of facility seedling cultivation research.