Use of in-situ field chambers to quantify the influence of heat stress in chickpea (Cicer arientinum)

Abstract

Chickpeas (Cicer arientinum) are commonly grown in parts of the world limited by heat stress, and this is likely to increase under climate change. In-field heat chambers were used to understand the response of chickpea pollen and yield to stress in-situ, and their utility in screening breeding material for heat tolerance. Replicated plots of a putative heat tolerant and heat susceptible cultivars were sown under commercial agronomic conditions in two seasons. Clear perspex air-conditioned chambers set at 4 °C above ambient temperature were placed over yield plots for 2 weeks at flowering. Chambers set to mimic ambient conditions, open-sided perspex shelters, and un-chambered plots of both cultivars were also randomised throughout the experiment to validate the method. Heat chamber treatment reduced yield between 9 % and 41 % compared to ambient chambers. The ambient conditions during the 2-week trial in both seasons were in the non-stressful range for heat, however both chilling stress and frost were observed. The heated chambers reached temperatures above 35 °C, but not for enough time to cause significant pollen sterility in either season. This was suggested by > 78 % pollen viability found at the conclusion of the heat chamber period. However, a significant chamber effect was observed, with plants under ambient chambers significantly taller than non-chamber and shelter plots. A yield reduction of between 11 % and 24 % was observed in the open-sided perspex shelter compared to the non-chamber treatment. The method will be refined by including set maximum daytime and minimum night temperatures to guarantee the targeted stress during the experimental period. The length of time of chamber application necessary to discriminate heat treatments, but minimise the chamber effects, will also be investigated. Despite this, heat-induced yield differences between genotypes suggests these chambers are a useful tool to screen for heat tolerance and research plant physiological responses.