Document Type : Research articles.
Authors
Crop physiology Res. Dep., Field Crops Res. Institi., A.R.C., Egypt.
Abstract
A field trail was conducted at Ismailia Agricultural Research
Station during the two successive seasons 2006 and 2007 to study the
physiological response of sesame cv. "Shandaweel-3" to three levels of
available soil moisture depletion (ASMD) namly wet (20-25%), medium
(45-50%) and dry (65-70%) as well as potassium fertilization at the rates
of 0, 24, 48 kg K2O/fed and spraying 1% K2O alone or in combination
with added 24 kg K2O/fed. Results of combined analysis could be
summarized as follows:
- Increasing soil moisture stress up to 65-70% ASMD significantly
decreased plant height, fruiting zone length, leaf area index (LAI) at
56, 70 and 84 days after sowing (DAS), relative growth rate (RGR),
net assimilation rate (NAR) at 56-70 and 70-84 DAS, total
chlorophyll, carotenoides contents of leaves and chlorophyll
fluorescence. Whereas, proline content in leaves was significantly
increased. Dry treatment significantly reduced 1000-seed weight,
number of capsules, capsules, straw and seed weights/plant, straw and
seed yields/fed as well as total carbohydrates and oil contents in seeds.
Exposing sesame plants to severe water deficit decreased relative
water content of leaves (RWC), seasonal water consumptive use
(WCU), water use efficiency (WUE) and transpiration rate (TR), while
stomatal resistance (SR) was increased. The maximum value of WUE
was obtained when plants received medium treatment compared with
wet or dry treatments.
- Applying 24 kg K2O/fed in combination with spraying 1% K2O
significantly increased plant height, fruiting zone length, LAI at 56, 70
and 84 DAS, RGR at 56-70 and 70-84 DAS, NAR at 56-70 DAS, total
chlorophyll, carotenoides contents of leaves, chlorophyll fluorescence,
1000-seed weight, number of capsules, capsules and seed
weights/plant, straw and seed yields/fed. While, straw weight/plant
was significantly increased when plants received 48 kg K2O/fed.
Proline content of leaves and SR significantly increased without
adding potassium fertilizer. The maximum value of total carbohydrates
and oil contents in seeds, RWC, TR, WCU and WUE recorded the
highest values when plants were treated with 24 kg K2O / fed and
sprayed by 1% K2O.
- The interaction effect between water stress and potassium fertilization
was found to be significant on LAI at 56 DAS, carotenoides content of
leaves at 70 and 84 DAS, chlorophyll fluorescence, leaf proline
content, number of capsules/plant, capsules, seed and straw
weights/plant, total carbohydrates and oil contents in seeds, RWC at
70 and 84 DAS, SR and TR. The maximum value of WUE was
obtained when plants were irrigated at 45-50% ASMD and received 24
kg K2O / fed with spraying 1% K2O.
Keywords
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