Phenological sensitivity to high temperature stress determines dry matter partitioning and yield in potato

Effect of high temperature stress through different dates of planting and growing inside temperature tunnel were investigated in two contrasting potato cultivars Kufri Surya and Kufri Chipsona-3. High temperature exposure at early, late and tunnel environment delayed tuber initiation and shortened the bulking duration of both the potato cultivars. High temperature significantly decreased crop growth rate, tuber growth rate and net assimilation rate. Under high temperature, K. Chipsona-3 and K. Surya recorded 26–71% and 16–40% reduction in marketable yield. Yield attributes such as number of tubers, mean tuber weight and dry matter of tubers were significantly reduced in K. Chipsona-3. Moreover, higher phenological sensitivity of K. Chipsona-3 under high temperature stress resulted in reduced dry matter partitioning towards tuber. Our results demonstrated that phenological shift under high temperature stress is critical during tuber initiation that decides number of tubers and marketable yield in potato. Temperature inside poly-house tunnel was most detrimental for tuber initiation as well as bulking stage. Thus, precautions should to be taken to explain yield losses under growth chamber or tunnel conditions, which do not represent natural field conditions. Among two potato cultivars, K. Surya showed higher temperature tolerance as compared to K. Chipsona-3 under all high temperature environments. This could be attributed to higher assimilate partitioning efficiency of K. Surya towards tuber during bulking phase.