Effect of temperature dynamics on phenological and horticultural performance of different citrus mandarin genotypes growing under a temperature gradient tunnel

Abstract

Citrus is an important fruit crop and primarily cultivated in tropical and subtropical regions of the world. The quality of the citrus fruit is highly vulnerable to rise in temperature and hence impacts the profitability of the growers. With this key objective, a study was conducted on three main mandarin genotypes i.e. G1- Kinnow, G2- Daisy and G3- W. Murcott, which were exposed to elevated temperature regime of +1.51, +2.03 and +2.29ºC from ambient conditions within a Temperature Gradient Tunnel (TGT). The phenological behavior of the genotypes i.e. beginning of bud burst (BBCH1) to fruit maturity (BBCH97) was advanced by 1–15 days in G1, 1–29 days in G2 and 1–17 days in G3 as compared to ambient conditions. The elevated temperature had a depressing effect on fruiting density (4.76-54.30 no/m3), tree yield (5.81-60.20 kg/tree), yield efficiency (9.26-58.52 kg/m3), fruit weight, size and organoleptic traits i.e. TSS. Kinnow exhibited high tolerance to elevated temperatures, as revealed by mild effects on horticultural traits, and plant growth characteristics i.e. plant height, canopy volume, fruit scaring and leaf burning. Moreover, multivariate analysis depicts differential significant associations between horticultural traits and analogous interconnection of mandarins under different temperature regimes. Thus, we conclude that an increased temperature in the future climate change scenario will have negative genotypic-specific effects on the phenological and horticultural performance of citrus cultivars. This differential varietal response can help citrus growers with better management of orchards for profitable production and scientists to adapt to the challenges posed by a futuristic warming climate.