An efficient greenhouse method to screen potato genotypes for drought tolerance

Potato (Solarium tuberosum L.) is the third food crop in the world. China is the biggest potato producer worldwide where 60% of the potato crop is cultivated in arid and semi-arid climates, Only a few varieties with high drought tolerance were released in China. It is important to accelerate the selection of drought resistant cultivars in a fast, simple and efficient method. Ten advanced clones, which were selected based on the results from two-years drought evaluation trials, along with two widely-adopted cultivars in China with contrast-drought resistance were evaluated under well-watered condition and water restriction condition. Plant traits related to gas exchange, chlorophyll, specific leaf area (SLA) and leaf dry matter content (LDM) were collected at 0, 20, 40 and 60 days after water restriction. Moreover, tuber number and tuber yield were measured at harvest. Tuber number and weight were reduced by drought. The drought index (DI) of the pot trial had a strong correlation with that of the field trial. Net photosynthesis and stomatal conductance were related to yield in the early stages. SLA and LDM had significantly positive and negative correlations respectively with DI after water restriction. Genotype C93 had the highest DI and yield stability followed by C112, C46 and C82 in the pot trial. All had better performance than the best local variety Tacna. Our findings suggested that the four clones above can be good candidates for drought tolerance breeding. SLA and LDM could be the low-cost and efficiency indicators for potato drought resistance selection after tuber initiation.