Crop Protection & Environmental Biology

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Subject: search.filters.subject.Light Intensity

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    Growth, chlorophyll and carotenoids contents of tea (Camellia Sinensis (L) O. Kuntze) under varied light intensity in Southwest Nigeria
    (Elixir International Journal, 2023) Adeosun, A.; Togun, A. O.; Adejumo, S. A.
    The nutritive and anti-oxidative properties of tea have made it the most widely consumed beverage in many parts of the world. Warm climatic conditions arising from high light intensity however, constitutes a major constraint to tea cultivation in South-Western Nigeria. Reduction in the Light Intensity (LI) is therefore, fundamental to the possible expansion of tea production in this zone. A pot experiment was carried out to evaluate the effect of different light intensities on growth, leaf chlorophyll and carotenoids contents of two tea cultivars at two locations (Ibadan and Owena). The experiment was a factorial of eight treatments; Two tea cultivars (143 and 318), Four levels of light intensity-(25%=2.40x104lux, 45%=4.57x104lux, 65%=6.75x104lux and 100%=1.04x105lux: control). These were achieved by using sheds of 4, 2, 1 and 0 palm fronds layers, respectively. The experiment was laid out in completely randomized design with four replications. Data were collected on Number of Leaves (NL), Leaf Area (LA, cm2), Plant Height (PH, cm), leaf abscission as well as chlorophyll and carotenoids contents (mg/g). The data were analyzed using descriptive statistics and ANOVA at α0.05. The result revealed that Cultivar 143 performed significantly better than 318 with 25.23±9.74NL, 665.93±297.54LA in Ibadan and 25.38±9.82NL, 898.23±670.34LA in Owena. Tea plants under 45 and 65% LI had higher NL, LA and PH compared to those grown under 25 and 100% LI in Ibadan and Owena. Highest leaf abscission (15.44±3.89 and 23.13±7.22 dropped leaves in Ibadan and Owena, respectively) was obtained in C143 under 100% LI; while the least (6.84±3.89 and 4.78±7.22 dropped leaves in Ibadan and Owena, respectively) was obtained in C318 under 45% LI. In Ibadan, chlorophyll and carotenoids increased from 1.11±0.83 and 0.30±0.15, respectively in C318 under 100% LI to 3.15±0.83 in C143 under 25% LI and 0.6±0.15 in C318 under 45% LI; while in Owena, chlorophyll and carotenoids increased from 1.05±0.87 and 0.29±0.30, respectively in C143 under 100% LI to 2.97±0.87 and 0.83±0.30 in C318 under 25% LI. Conclusively, light intensities of 45% (4.57x104lux ) - 65% (6.75x104lux) enhanced optimal vegetative growth, reduced leaf abscission, increased chlorophyll and carotenoids accumulation of tea cultivar 143 which was more adaptable to Ibadan and Owena, Southwest Nigeria.
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    Physiological responses of cowpea simultaneously exposed to water deficit stress and varying light intensities at vegetative and reproductive growth stages
    (Update Publishing House, 2022) Adeniyi, O. I.; Adejumo, S. A.; Fofana, M.; Adegbehingbe, F. T.
    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.