Relationship between the Dynamic Characteristics of Tomato Plant Height and Leaf Area Index with Yield, under Aerated Drip Irrigation and Nitrogen Application in Greenhouses

Abstract

The current study was undertaken to investigate the dynamic characteristics of the tomato crop, such as its plant height and leaf area index (LAI), based on the effective cumulative temperature. This was assessed under aerated drip irrigation (ADI) conditions and the application of a specific nitrogen (N) dose, and their relationship with the yield of the crop was formulated. The study was conducted in a greenhouse located in Zhengzhou, Henan province, China. The assessment conditions were the two irrigation methods, ADI and conventional drip irrigation (CK), and the three N application rates, i.e., 0, 140, and 210 kg ha−1. The logistic and Richards models were used to fit dynamic equations for plant height and LAI under the different treatments to quantify the characteristic parameters and understand their relationship with yield. The results revealed that the growth of the tomato plant fitted well with the logistic and Richards model at R2 > 0.98 (p < 0.01), regardless of the treatments. ADI and N application were found to significantly increase the maximum growth rate and average growth rate over the rapid growth period based on the tomato plant height and LAI. They were also noted to reduce the effective cumulative temperature at which plant height entered the rapid growth period (p < 0.05), thereby increasing the time spent in the nutritional growth phase. This is an essential precursor for the better development of subsequent reproductive organs. Tomato yields also confirm it: the highest yield of 85.87 t ha−1 was obtained with 210 kg N ha−1 for the ADI treatment, with an increase of 13.8%, 12.2%, and 39.6% compared to the CK–210 kg N ha−1, ADI–140 kg N ha−1, and ADI–0 kg N ha−1 treatments, respectively (p < 0.05). Grey correlation analysis showed that the characteristic parameters closely related to yield were all from the ADI and N application treatments. Furthermore, it was observed that the effective cumulative temperature and the maximum growth rate of the LAI at which the LAI entered the slow growth phase were the key growth characteristic parameters affecting tomato yield. This study provides a scientific basis for regulating the growth dynamics and yield of vegetables in greenhouse facilities under ADI and N application.