Autor:innen:
Anna M. Sauer | Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth | Germany
Sara Loftus | Georg-August Universität Göttingen, Biogeochemistry of Agroecosystems
Eva-Maria Görk | Georg-August Universität Göttingen, Biogeochemistry of Agroecosystems
K. Sudhabindu | Centurion University of Technology and Management, Paralakhemundi, Odisha, India
L. K. Erugoti | Centurion University of Technology and Management, Paralakhemundi, Odisha, India
Dr. Jana Kholová | Crop Physiology Laboratory, International Crops Research Institute for Semi-Arid Tropics (ICRISAT), India
Prof. Dr. Michaela A. Dippold | Geo-Biosphere Interactions, Department of Geosciences, University of Tuebingen
Dr. Mutez A. Ahmed | Department of Land, Air and Water Resources, University of California Davis, United States
Water limitation in agriculture is an increasing problem, especially in semi-arid and arid regions undergoing climate change. Sorghum (Sorghum bicolor (L.) Moench) is well adapted to drought stress and is an important staple crop in these areas. A broad genetic variety of locally adapted wild forms and landraces shows a high potential for drought adaptions to increasingly extreme climates.
Thus, M-35, the most popular genotype for decades in the post-rainy season in India, was compared with four landraces from Africa and Pakistan to evaluate their performance under drought conditions. These five genotypes were grown in 2 m deep lysimeters on soils of four different soil textures (silty clay, sandy loam, loamy sand, sand) which were dried during flowering stage to 30% usable field capacity and weighed weekly to assess transpiration. Additionally, two nitrogen (N) source treatments labeled with 15N, mineral N fertilizer versus cowpea organic N residues, were imposed to test the influence of legume pre-crops and biopore-utilization on sorghum’s water and N use.
Although N recovery rates in the mineral N fertilizer treatment were higher than with the pre-crop, the ANOVA test showed no significant effect of N utilization on plant development, transpiration, or yield. Plants in silty clay grew tallest, produced the most biomass, and hence had the highest total transpiration. Interestingly, they also had tendentially the highest transpiration efficiency (TE) and harvest index (HI). These trends were opposite in sand, where especially the otherwise vigorously growing genotypes IS15945, IS8348, and M-35 showed strongly reduced plant height and biomass production. A later flowering time was associated with reduced HI. While the elite line M-35 showed the highest TE irrespective of the soil texture (up to 6 g/kg), it suffered from late flowering and yield loss on soils of all textures, with the effect being more pronounced when growing on a sandy soil. The landraces IS29914 and IS8348 showed stable HI even on sandy soils, irrespectively of their lowest TE.
The study could overall emphasize the high potential of sorghum landraces to overcome more extreme climate conditions imposed by climate change. For future breeding, a combination of high and stable TE as seen in M-35 together with traits such as early flowering shown by some of the landraces could be a promising approach to adapt cultivars to extreme climates and soils with low water-holding capacities.