Response of two maize inbred lines to drought and phosphorus stress

Drought and phosphorus deficiency frequently co-occur in the red soil region of southern China and severely limit maize growth and productivity; however, the interactive effects of these two stresses and the genotypic differences in their combined tolerance remain poorly understood. This study evaluated the individual and combined effects of drought and phosphorus supply on the growth of two maize inbred lines (Line1 and Line129) with contrasting stress tolerance. A pot experiment was conducted using a randomized complete block design with three factors: genotype, phosphorus level (low and high phosphorus), and water regime (well-watered and drought). Biomass accumulation, leaf development, root morphology, and plant phosphorus content were measured at the seedling stage. Drought, phosphorus, interaction of drought and phosphorus significantly affcted shoot, root, leaf and sheath dry weight, total root length, distribution and phosphorus content of two lines. Drought caused significantly reduced shoot, leaf and root dry weight, final total leaf area by 36 %, 30 %, 34 %, 30 % in Line 129 under low phosphorus supply, whereas no significant reductions were observed in Line1. Low phosphorus supply increased the root:shoot ratio by 20 % in Line1 and 35 % in Line129 across water regimes, Line1 consistently maintained a higher root:shoot ratio than Line129. We conclude that Line1 was more drought and low phosphorus tolerant than Line129, and our findings are critical for breeding of drought and phosphorus stress tolerant maize in red soil region of southern China.