Abstract
A combination of stresses as it occurs on the field poses more challenges to crop production than individual stress. Crops’ response to single stress also differs from that of combined stresses. The morpho-physiological responses of two cowpea varieties (IT89KD-288 and IT99K573-1-1) to a combination of stresses (water deficit stress and high light intensity) were investigated at different growth stages. Three levels of light intensities (L3: 259 Lux- 36%, L2: 394 Lux-55% and L1: 710.2 Lux-100%) were imposed using one, two and zero layer(s) of the net, respectively, while, water deficit stress at four levels (W1: no water stress; 0-5 bars, W2: moderate water stress; 5-15 bars, W3: moderately-severe; 15-40 bars and W4: severe water stress; 40 -70 bars) was imposed differently at vegetative and reproductive growth stages. Data were collected on the cowpea yield, Leaf Temperature (LT), Chlorophyll (C), Photosynthesis (P), Stomatal Conductance (SC) and Canopy Transpiration Rate (CTR). Exposure to W4 under L1 considerably reduced cowpea yield by 80% compared to those grown under L3 and full watering. Reduced light intensity enhanced cowpea grain yield irrespective of water deficit stress and IT89KD-288 was superior to IT99K573-1-1. Reduction in light intensity also increased the SC from 55.18 in L1 to 76.88 in 36 % L3. Full light intensity without water stress (100% light intensity), increased C content, while severe water stress reduced the C content and CTR. Photosynthesis was, however, reduced under low light intensity compared to 100% light intensity. It was also observed that water deficit stress imposed at the reproductive stage did not affect P, CTR and SC unlike that of the vegetative stage. In conclusion, reduced light intensity enhanced cowpea tolerance to water deficit and increased yield. Cowpea response was dependent on growth stage, variety and severity of stress.
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Claims 8
Claim · model-written summary
Severe water stress under full light reduced yield by 80% against low light and full water.
- Taxon
- cowpea
Vigna unguiculatae0 - Treatment
- W4 under L1e0
- Outcome
- cowpea yielde0
- Direction
- reducede0
- Value
- 80%e0
- Comparator
- L3 and full wateringe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exposure to W4 under L1 considerably reduced cowpea yield by 80% compared to those grown under L3 and full watering”
Claim · model-written summary
Reduced light increased grain yield regardless of water deficit.
- Taxon
- cowpeaVigna unguiculatae0
- Treatment
- Reduced light intensitye0
- Outcome
- cowpea grain yielde0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduced light intensity enhanced cowpea grain yield irrespective of water deficit stress”
Claim · model-written summary
IT89KD-288 exceeded IT99K573-1-1 in grain yield.
- Taxon
- cowpeaVigna unguiculatat0
- Material
- IT89KD-288e0
- Outcome
- superiore0
- Direction
- superiore0
- Comparator
- IT99K573-1-1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“IT89KD-288 was superior to IT99K573-1-1”
t0“cowpea”
Claim · model-written summary
Reduced light raised stomatal conductance from 55.18 to 76.88.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- 36 % L3e0
- Outcome
- SCe0
- Direction
- increasede0
- Value
- 76.88e0
- Qualifier
- 55.18e0
- Comparator
- L1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduction in light intensity also increased the SC from 55.18 in L1 to 76.88 in 36 % L3”
t0“cowpea”
Claim · model-written summary
Full light without water stress increased chlorophyll content.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- 100% light intensitye0
- Outcome
- C contente0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Full light intensity without water stress (100% light intensity), increased C content”
t0“cowpea”
Claim · model-written summary
Severe water stress reduced chlorophyll content and canopy transpiration.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- severe water stresse0
- Outcome
- C content and CTRe0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“severe water stress reduced the C content and CTR”
t0“cowpea”
Claim · model-written summary
Low light reduced photosynthesis versus full light.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- low light intensitye0
- Outcome
- Photosynthesise0
- Direction
- reducede0
- Comparator
- 100% light intensitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photosynthesis was, however, reduced under low light intensity compared to 100% light intensity”
t0“cowpea”
Claim · model-written summary
Reproductive-stage water deficit did not affect photosynthesis, transpiration or stomatal conductance.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- water deficit stress imposed at the reproductive stagee0
- Outcome
- P, CTR and SCe0
- Direction
- did not affecte0
- Comparator
- vegetative stagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“water deficit stress imposed at the reproductive stage did not affect P, CTR and SC unlike that of the vegetative stage”
t0“cowpea”
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