A Growth Model to Estimate Shoot Weights and Leaf Numbers in Tea

Abstract

Increases in plant weight are strongly correlated with the amount of solar radiation that the plants receive. However, tea (Camellia sinensis) growth models are limited in their ability to integrate solar radiation into the predictions. In this study, we developed a predictive model for estimating tea shoot weights based on solar radiation and air temperatures. We combined information on daily solar radiation and daily air temperature to estimate the dry weight and fresh weight of a shoot in a tea crop. In addition, the range of shoot weights and leaf numbers could be estimated based on weather records. The estimated dry weight increases per unit of solar radiation for air temperatures of < 15, 15–17, 17–19, 19–21, 21–23, 23–25, 25–27, 27–29, and >29°C were 0.043, 0.074, 0.075, 0.334, 0.480, 0.283, 0.122, 0.079, and 0.028 g MJ–1, respectively. The model results suggest that the estimated shoot weights were highly correlated with the observed weights for both dry weight (r = 0.75, p < 0.001) and fresh weight (r = 0.79, p < 0.001). The estimated fresh weight ranges of shoots having two to six leaves were 0.31–3.48, 0.16–3.53, 0.44–5.60, 0.66–6.74, and 2.09–9.91 g, respectively. This study provided a statistical procedure that can be used to estimate the growth of tea crops for agricultural researchers. The results provide a means of assessing production and planning harvesting dates for tea farmers in Taiwan.Core Ideas A method to predict the weight of tea shoot was developed using field investigations. Data of solar radiation and air temperature were used to estimate shoot weights. The highest dry weight increases to solar radiation was 0.48 g MJ–1 at 21 to 23°C. The estimated weight range of shoots can be used to schedule dates for shoot plucking.