Establishment of predictive model of litchi flowering rate based on meteorological factors

【Objective】This study aimed to develop a prediction model of litchi flowering rate and a system of warmth damage indicators， thereby providing a scientific basis for flowering quantity estimation， meteorological forecasting and warning， as well as plan making of disaster prevention and mitigation.【Method】Taking the main variety Feizixiao of Hainan litchi as research objects and based on phenological materials and meteorological observation of 8 litchi demonstration orchards from 2011 to 2024， a flowering rate prediction model of Hainan litchi Feizixiao was established using a second-order polynomial surface fitting method， and the spatiotemporal distribution characteristics of warmth damage during litchi flowering induction period in the study area were analyzed.【Result】During the flower bud induction period of litchi Feizixiao， low and high temperatures fluctuated obviously， as chill accumulation （≤15 ℃） and heat accumulation （≥28 ℃） were key meteorological factors affecting the flowering rate. The established second-order polynomial prediction model was expressed as z=-0.53x²+0.81x+0.23xy+0.04y²-0.19y+0.69， with a coefficient of determination （R²） of 0.86， a correlation coefficient between predicted and observed values of 0.951， and the root mean square error and standard deviation of 0.038 and 0.095 respectively， indicating a high prediction accuracy and generalization ability. In terms of the spatiotemporal distribution of warmth damage， higher chill accumulations were found in nor-thern and northwestern cities （counties） such as Baisha， Haikou， Danzhou， Chengmai， and Dingan， where the average chill accumulation>100.0 ℃·d， indicating the sufficient chilling units， adequate flower bud induction， and low frequency of warm damage， with the average flowering rate exceeding 90%. Lingshui at the southern region had the lowest average chill accumulation （38.9 ℃·d）， while Ledong had the highest average heat accumulation （29.2 ℃·d）； the southern regions were more frequently affected by warmth damage， with risks of moderate to severe events， and in 2016 and 2024， it was hit by relatively severe warmth damage.【Conclusion】The established prediction model of litchi flowering rate can provide technical support for monitoring litchi flowering and early warning of warmth damage. As the climate continues to warm in the future， the flowering promotion and shoot growth control of litchi face increasing challenges， so optimizing cultivar composition and strengthening research on climate adaptability are essential to improving yield and quality of litchi.