Abstract:

To elucidate the dynamic changes in agronomic traits and nutritional quality of Poa forage under water deficit conditions, 3 native germplasms, namely Poa pratensis, Poa pratensis var. anceps Gaud. cv., Poa crymophila, were used as experimental materials. 3 soil moisture levels were established, including 60% (control), 45% (moderate water stress) and 30% (severe water stress). The growth performance, nutritional quality and drought resistance of the tested materials were investigated systematically. The results showed that: (1) with the intensification of water deficit, the fresh weight, dry weight, plant height, relative water content (RWC), crude protein (CP), ether extract (EE) and relative feed value (RFV) of 3 forage varieties decreased significantly by 1.97%-34.93% (P<0.05); the contents of neutral detergent fiber (NDF) and acid detergent fiber (ADF) increased significantly by 4.61%-13.58%; (2) two-factor analysis showed that the agronomic and quality indicators of forages were jointly affected by genotype and water stress, and these indicators were more sensitive to water deficit; (3) grey correlation degree evaluation indicated that the drought resistance and production performance were ranked as follows: P. pratensis>Poa pratensis var. anceps Gaud. cv.>P. crymophila; (4) path analysis revealed that the direct effects on dry weight were ranked in the order: fresh weight>RWC>plant height>CP>RFV>EE>Ash>NDF>ADF. Among them, fresh weight, RWC, plant height and CP exerted major positive effects. In conclusion, P. pratensis is suitable for popularization in arid and semi-arid regions because of its good growth, stable yield, superior quality and strong drought resistance under water deficit conditions, and can serve as an excellent germplasm resource for artificial grassland establishment and degraded grassland restoration.

Key words: Poa, water deficit, production performance, nutritional quality, grey correlation evaluation