Effect of High Temperature Stress on Pollen Grains in Sunflower (Helianthus annuus L.) Inbred Lines

Abstract

High temperature at reproductive stage causes a decrease in seed set that ultimately results in yield loss in important crops. Limited research is available regarding the effect of high temperature on viability attributes of pollen grain in sunflower. This study was planned to reveal the effects of high temperature stress on pollen grains in sunflower. An experiment was laid out in a triplicated Completely Randomized Design with split-split plot arrangements at the Oilseeds Research Institute, Ayub Agricultural Research Institute Faisalabad during spring 2021. Two temperature treatments T1 = 45° C for 10, 20 and 30 minutes, and T2 = 50° C for 3, 5 and 10 minutes were used on 10 sunflower inbred lines. Normal (untreated) pollen grains were used as control (T0). Data were collected on pollen viability, pollen germination, and pollen tube length. Recorded data were subjected to analysis of variance, Tukey’s HSD mean comparison test, and correlation. According to the results, ORI-1 showed the highest mean for pollen viability, whereas, RL-86 had highest mean for pollen germination and pollen tube length under normal conditions. RL-86 and ORI-73 revealed their ability to withstand both heat stresses as all pollen traits were least affected under high temperature stresses. It is advised to incorporate these inbred lines in future breeding programs aimed at the development of heat tolerant sunflower hybrids. Moreover, correlation studies displayed a positive, strong and highly significant relation of pollen germination with pollen tube length under normal and heat stress conditions revealing their importance in pollen study and reproduction.

Keywords:
Abiotic stress tolerance; pollen germination; pollen tube length; pollen viability; sunflower

HIGHLIGHTS

• Pollen grains of ten sunflower inbred lines were evaluated under normal and high temperature stress conditions.

• Two temperature treatments and three treatment times were used as factors

• Pollen viability, pollen germination percentage and pollen tube length decreased with increasing temperature and time period.

• RL-86 and ORI-73 showed excellent ability to withstand high temperature stress.