Seed size and water potential effects on water uptake, germination and growth of lentil

Seed size is an important parameter for plant growth and yield. The effects of seed size and water potential on seed water uptake, germination and early growth of lentil (Lens culinaris Medik. cvs. Jor-1 and Jor-2) were investigated. Rate of water uptake by seed size (small, medium and large) from solutions containing different water potentials (0, -0.5 and -1.0 MPa, as polyethylene glycol-8000) was higher in large than in medium or small seeds of both cultivars, regardless of water potential. Rate of water taken into seeds was higher in Jor-2 than in Jor-1. Decreasing water potential (more stress) had adverse effects on rate of water uptake by seeds in both cultivars. In another experiment, with lentils grown in a greenhouse at different soil metric potentials (-0.03, -0.15 and - 0.30 MPa), seed size or cultivar had no effects on germination percentage (GP), but GP was reduced as soil water potential decreased (more stress). In greenhouse soil, shoot dry matter (SDM), root dry matter (RDM), plant height, total root length (TRL) and number of primary branches per plant of 35-day-old plants from large seeds were larger than those of plants from medium and small seeds of both cultivars. Increasing soil water deficit progressively decreased each of these traits. Plants from large seeds had higher SDM, RDM and TRL than those from small seeds at intermediate soil water potential (-0.15 MPa) in comparison with the control (-0.03 MPa) or severe (-0.30 MPa) soil water potentials. Larger seeds produced larger plants than smaller seeds, and this appeared to be more pronounced under intermediate than well-watered or more severe water-stressed conditions. Faster early growth of plants from larger seeds may be advantageous in establishing plants under semiarid conditions.