Optimum Seed Harvest Time of Trifolium lupinaster L. in Relation to Flowering, Pods and Seed Characteristics

Pod splitting is the main cause of the low seed yield of legume forage grasses. In the present study, the flowering pattern, seed maturity characteristics and the optimum seed harvesting time of Trifolium lupinaster L. were investigated to improve seed yield and quality.

All the required observations for this study were completed in the new line nursery from July to October 2022. Flowering habits of populations, individual plants, inflorescences and florets were observed for two consecutive months from July 1 to September 1 and daily temperatures and humidity were recorded. Observations on the state of seed and pod development were made by sampling and measuring in three batches every three days from July 25 to August 23 starting from the 12^th day after the first flower and continuing until the first day of the season. Starting from July 15, seed yield and constitutive factors were measured every 10 d until September 5^th.

The results showed that the flowering period of T. lupinaster L. population lasted for 60 days and the peak opening period was on the 11^th-20^th day after heading began, the florets opened most vigorously at 11:00-13:00 every day and inflorescences were opened more vigorously at 15:00 every day. The opening pattern of florets and inflorescences was greatly affected by temperature and humidity. The fresh weight of pod skin and seeds reached the maximum on the 15^th day after flowering; the length and width of pods and seeds reached the maximum on the 18^th day; the water content of pod skin and seeds began to decrease sharply on the 21^st day, while the pods began to crack and the surface of the seeds dried and hardened; the water content of seeds decreased to below the safe storage moisture at 27 days. Our resuts showed that mid-August was the optimum seed harvesting period for T. lupinaster L.