2.1 Plant material and growth conditions
Three-week-old seedlings of tomato (Solanum lycopersicumL.) cultivar ‘Micro-Tom’ were planted in pots containing 150 g of
soil composing of peat, vermiculite and perlite (4:2:1) and grown in a
growth chamber with 24/20⁰C (day and night)
temperatures, constant 60% relative humidity, 16 hours photoperiod and
light intensity of 150 μmol m-2 s-1.
Plants were watered regularly until reproductive development. About
binucleate stage of pollen development of the first flower buds, plants
were exposed to two watering regimes: Well-watered (WW), soil moisture
65 ± 5%, and drought stress (DS), soil moisture 6 ± 3% by withholding
watering in the DS plants. Soil moisture was monitored using HH2 Soil
Moisture Meter (Delta-T Devices, Cambridge, UK) until it decreased to
5%. The soil moisture was then maintained at 6 ± 3% for 4 days,
thereafter normal watering resumed. Meanwhile, the WW plants were
watered normally. Pollen development stages were estimated by
measurement of bud length and staining with 4,
6-diamidino-2-phenylindole (Regan and
Moffatt, 1990).