Accessing Drought Tolerance Capacity in Stylosanthes Guianensis Germplasm.

Stylosanthes guianensis (Aubl.) Sw. is a perennial tropical legume native from South America. It is used in grass–legume mixed pastures, protein banks and crop-pasture integrated systems. The Stylosanthes guianensis germplasm collection at Embrapa Cerrados comprises more than 500 accessions. Global climate changes will impose strong modifications, among others, on the rainfall regimes in different ecosystems. The actual crop systems must be modified and adapted to face these changes. One of the strategies is to select plants that will tolerate water restrictions during its growing period. The objective of this research was to access drought tolerance in Stylosanthes guianensis.Ten accessions were selected from the Embrapa Cerrados germplasm collection based on morphoagronomic characteristics and genetic divergence. A greenhouse experiment in a complete randomized design with ten germplasm accessions and three soil field capacities (FC) was established with four replications. Seedlings with 75 days were transferred to 5 kg pots containing a typical Cerrados Oxisol, previously dried. Water was added until 20%, 40% and 60% field capacity was achieved.  Plants height, number of branches and leaves, amount of clorofila A, B and total, and plant stems and leaves dry matter yield were evaluated 75 days after transplanting. Accessions CPAC 135, 1230, 1371, 4199, 4227 and 4285 survived to the 20% field capacity treatment during the 75 days that last the experiment. In general, the plants on the 20% FC treatment achieved only 12% of the performance of the 60% FC, and the 40% FC plants achieved 88% of the performance of the plants growing with 60% FC. Stylosanthes guianensis presented genetic variability in terms of drought tolerance that could be used direct to select new cultivars or to establish a breeding program seeking this characteristic.

This research was sponsored by: “Parceria UNESP/Banco ABN-AMRO-Real