1. Klebernilson O. Lima and Liv S. Severino
SEED GROWTH RATE AND SEED FILLING DURATION OF CASTOR SUBJECTED TO DIFFERENT AIR TEMPERATURES
Klebernilson O. Lima and Liv S. Severino
2014 AAIC Meeting
Athens, Greece

2. The temperature has great influence on the filling of the castor bean
Introduction
The temperature has great influence on the filling of the castor bean
The weight of a seed is determined by the growth rate multiplied by the filling period
Peak temperatures can potentially cause reduced productivity

3. Division and cell expansion
Divisão e expansão celular Enchimento Dessecação
Division and cell expansion
Filling
Desiccation
Temperature can affect differently each of these phases because they consist of quite distinct physiological processes

4. Phase I - Division and cell expansion
The seed is very vulnerable to environmental stresses
Physiological condition of the mother plant

5. Phase II - Filling
Conversion of assimilates in reserve materials (oil and protein)
The seed is less sensitive to most environmental stresses (except temperature and oxygen)
Physiological condition of the mother plant has little influence

6. Phase III - Drying
The seed loses vascular contact with the mother plant
Water loss is controlled by the physical properties of the fruit, seed, and environment

7. Objective
To measure the seed growth rate and seed filling duration of castor seed as influenced by the air temperature and to estimate the cardinal temperatures of this physiological process.

8. Methods
Castor plants of the line CNPA , selected in the breeding program of Embrapa (Brazil),
Cultivated in 15-L pots in a growth chamber.
The plants were fertilized with NPK at planting and with N at flowering time.
Irrigation was made daily.

9. Methods
The plants were raised at 200 µmol m-2 of photosynthetically active radiation and 30 °C of temperature before blooming.

10. The first raceme was tagged when five female flowers were open, the date was registered;
A fruit was collected three time per week until the fruits turned brown.

11. Methods
Immediately after harvesting the fruits, seeds were manually extracted, weighed, measured (length, width, and height), and transferred to an oven to dry for 48h at 80 °C.
After drying, the seed was weighed. Data was used to calculate seed volume and water content.
Calculations were made to detect and discard aborted seeds and seeds that grew significantly ahead or behind the majority of seeds of the same age.

12. When complete, the experiment will cover the range of
Results
The study is on progress, and the treatments with three temperatures were concluded:
26, 30, and 34°c
When complete, the experiment will cover the range of
18 to 42 °C.

13. Results In total, 2114 seed were collected
But some seeds were excluded as
Aborted (12.9%)
Late or early growth (10.6%)
Processing errors (4.2%).

14. A seed is considered aborted when it meets three conditions:
1- The water content is lower than 80%. This criterion ensures that the seed had already left the stage when I was taken. 2) The dry weight of the seed is 60% lower than that estimated for a seed having the same moisture content value. This criterion eliminates the seed that stopped growing at an earlier stage. 3) The seed is less than 40% of the maximum seed weight.

15. Results 26°C 17 days 19 days 36 days 30°C 14 days 18 days 32 days 34°C
TEMPERATURE
DURATION OF THE PHASE OF EXPANSION AND CELL MULTIPLICATION
DURATION OF THE FILLING PHASE
TOTAL TIME
26°C
17 days
19 days
36 days
30°C
14 days
18 days
32 days
34°C
13 days
26 days

16. Results
The higher temperature also caused a reduction in volume that instead of expanding to about 100 mm3, was limited to the volume of 70 mm3.

17. The reduction of the water content (below 80%) demonstrates the seed stage of closed cell multiplication started, and the fill phase. Under temperature of 26 ° C, the castor seed took 17 days in Phase 1 and 19 days in the Phase 2

18. Under the lower temperature (26C), dry weight slowly grew, as noted by the data of water content.
Under temperature of 30 ° C, the dry weight increased rapidly and stabilized around 0.28 g

19. Partial conclusions
Castor seeds were confirmed to be very sensitive to air temperature
The seed maturation can be considerably delayed even by a temperature that would not affect general plant growth.
The cardinal temperatures were not determined because the study is in progress, and only the intermediate temperatures were tested.

20. Thank you! Klebernilson Lima
Trainee – Embrapa Algodão  Graduating in Agroecology – UFCG
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