Abstract
Dry seeding advances establishment and harvest of rainfed rice and may help the crop escape late-season droughts. Early establishment, however, may expose the crop to early and mid-season droughts and periods of low radiation during the grain formation phase. We conducted experiments in the 1992 and 1993 rainy seasons at Tarlac, Philippines, to investigate factors that may hinder the performance and yield of dry-seeded rice cv. IR72. The treatments included three seeding dates and three water regimes (totally rainfed, irrigated from seeding to complete emergence followed by rainfed, and fully irrigated). Drought stresses between panicle initiation and flowering, with a matric potential of -25 kPa to -60 kPa in the 0-10 cm soil layer, reduced final biomass by 20%–30%. The same stresses occurring during the vegetative stage delayed flowering 3-5 d, but did not reduce total biomass at harvest. High plant density of the dry-seeding culture (325-450 seedlings m–2) resulted in excessive vegetative growth (1600 -2200 tillers m–2 at maximum tillering stage). Inter- and intra-plant competition and low radiation (especially in typhoons) during anthesis and grain filling resulted in a high rate (40-70%) of tiller abortion, delay in flowering of later tillers, low percentage of filled spikelets (30-60%), and low yield (2.5–4.3 t ha–1), despite high biomass production (13-15 t ha–1). Selecting new varieties and devising cultural practices that ensure adequate plant population and weed competitiveness in drought years and avoid excessive vegetative growth in years with low radiation are research challenges to make full use of the potential of dry seeding to increase the productivity of rainfed lowland rice.
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Claims 9
Claim · model-written summary
Drought between panicle initiation and flowering reduced rice final biomass by 20%–30%.
- Taxon
- rice
Oryza sativat0 - Treatment
- Drought stresses between panicle initiation and floweringe0
- Outcome
- final biomasse0
- Direction
- reducede0
- Value
- 20%–30%e0
- Qualifier
- matric potential of -25 kPa to -60 kPae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Drought stresses between panicle initiation and flowering, with a matric potential of -25 kPa to -60 kPa in the 0-10 cm soil layer, reduced final biomass by 20%–30%”
t0“Rice”
Claim · model-written summary
Vegetative-stage drought delayed rice flowering by 3-5 d.
- Taxon
- riceOryza sativat0
- Treatment
- stresses occurring during the vegetative stagee0
- Outcome
- floweringe0
- Direction
- delayede0
- Value
- 3-5 de0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The same stresses occurring during the vegetative stage delayed flowering 3-5 d”
t0“Rice”
Claim · model-written summary
Vegetative-stage drought did not reduce rice biomass at harvest.
- Taxon
- riceOryza sativat0
- Treatment
- stresses occurring during the vegetative stagee1
- Outcome
- total biomass at harveste0
- Direction
- did not reducee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but did not reduce total biomass at harvest”
e1“stresses occurring during the vegetative stage”
t0“Rice”
Claim · model-written summary
High plant density in dry-seeded rice produced excessive vegetative growth.
- Taxon
- riceOryza sativat0
- Outcome
- excessive vegetative growthe0
- Direction
- excessivee0
- Value
- 1600 -2200 tillers m–2e0
- Qualifier
- 325-450 seedlings m–2e0
- Setting
- dry-seeding culturee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“High plant density of the dry-seeding culture (325-450 seedlings m–2) resulted in excessive vegetative growth (1600 -2200 tillers m–2 at maximum tillering stage)”
t0“Rice”
Claim · model-written summary
Competition and low radiation during flowering and grain filling caused 40-70% rice tiller abortion.
- Taxon
- riceOryza sativat0
- Outcome
- tiller abortione0
- Direction
- high ratee0
- Value
- 40-70%e0
- Qualifier
- competition and low radiatione0
- Setting
- during anthesis and grain fillinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inter- and intra-plant competition and low radiation (especially in typhoons) during anthesis and grain filling resulted in a high rate (40-70%) of tiller abortion”
t0“Rice”
Claim · model-written summary
Competition and low radiation delayed flowering of later rice tillers.
- Taxon
- riceOryza sativat0
- Outcome
- flowering of later tillerse0
- Direction
- delaye0
- Setting
- competition and low radiatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“delay in flowering of later tillers”
e1“competition and low radiation”
t0“Rice”
Claim · model-written summary
Competition and low radiation were linked to 30-60% filled rice spikelets.
- Taxon
- riceOryza sativat0
- Outcome
- percentage of filled spikeletse0
- Direction
- lowe0
- Value
- 30-60%e0
- Setting
- competition and low radiatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“low percentage of filled spikelets (30-60%)”
e1“competition and low radiation”
t0“Rice”
Claim · model-written summary
Competition and low radiation were linked to low rice yield of 2.5–4.3 t ha–1.
- Taxon
- riceOryza sativat0
- Outcome
- yielde0
- Direction
- lowe0
- Value
- 2.5–4.3 t ha–1e0
- Setting
- competition and low radiatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“low yield (2.5–4.3 t ha–1)”
e1“competition and low radiation”
t0“Rice”
Claim · model-written summary
The authors recommend selecting varieties and practices that maintain population and weed competitiveness in drought years while limiting excess growth in low-radiation years.
- Taxon
- riceOryza sativat0
- Outcome
- Selecting new varieties and devising cultural practicese0
- Qualifier
- drought years and avoid excessive vegetative growth in years with low radiatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Selecting new varieties and devising cultural practices that ensure adequate plant population and weed competitiveness in drought years and avoid excessive vegetative growth in years with low radiation are research challenges”
t0“Rice”
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