Seasonal effects of radiation and temperature on growth of greenhouse lettuce in a high insolation desert environment
TL;DR: In this paper, the authors measured the seasonal growth of three lettuce cultivars (Ostinata, Summer Bibb and Grand Rapids) in a greenhouse in a high-insolation desert environment and found that the best predictor of growth was the product of day temperature and the log of radiation.
About: This article is published in Scientia Horticulturae.The article was published on 1984-01-01. It has received 30 citations till now.
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TL;DR: Water content and cation accumulation in euhalophytes appeared to be coordinated to produce a constant osmotic potential gradient within the shoot tissues relative to the external salinity, in contrast, miohalophytes did not appear to regulate osmosis potential as closely as euh alophytes.
Abstract: . Growth rates and levels of minerals, Na+, K+, Mg++, Ca++, and water were measured in dicotyledonous halophytes grown along a salinity gradient from fresh water to 720 mol m−3 NaCl in a controlled environment greenhouse. Ten test species from the families Chenopodiaceae, Aizoaceae, and Batidaceae exhibited growth stimulation by 180 mol m−3 NaCl and were classified as euhalophytes. Ten others from the families Chenopodiaceae, Aizoaceae, Asteraceae, Brassicaceae, Polygonaceae, Boraginaceae, Malvaceae, and Plumbaginaceae showed their best growth on fresh water and were classified miohalophytes. Salt, and particularly sodium, accumulated in all halophytes but to a significantly greater extent among euhalophytes than miohalophytes. The water content of most species increased when grown on 180 mol m−3 NaCl compared to fresh water; but at higher salinities some of the species underwent dehydration. Dehydration of the succulent S. europaca was not coupled to a proportional decrease in growth. Water content and cation accumulation in euhalophytes appeared to be coordinated to produce a constant osmotic potential gradient within the shoot tissues relative to the external salinity. In contrast, miohalophytes did not appear to regulate osmotic potential as closely as euhalophytes.
139 citations
TL;DR: For five years experiments were performed in which lettuce (Lactuca sativa capitata L.) was grown in recirculating nutrient solutions as mentioned in this paper, in which ammonium/nitrate ratios and total nitrogen concentration were varied so as to lower the nitrate content of the lettuce heads.
Abstract: For five years experiments were performed in which lettuce (Lactuca sativa capitata L.) was grown in recirculating nutrient solutions. Both in winter and in summer, ammonium/ nitrate ratios and total nitrogen concentration were varied so as to lower the nitrate content of the lettuce heads. Fresh weight of the heads was mainly determined by global radiation during growth. In winter, when light was poor, the nitrate concentration of lettuce was considerably higher than in summer. Nitrate accumulation by lettuce was reduced when 20% of the total nitrogen in the solution, present as N03-N, was replaced by NH4-N. A further increase in the amount of NH4 in the nutrient solution a few weeks before harvest decreased the nitrate concentration of lettuce even more, while fresh weight of the heads was unaffected. Temporarily omitting all nitrogen resulted in the lowest nitrate concentrations, but also in a sharp decrease in fresh weight. When the N concentration of the solution was decreased in winter from 10 to 2....
95 citations
TL;DR: Using supplementary lighting resulted in significant increases in biomass, head firmness, and tipburn incidence and decreases in production cycle length, compared to natural light during four experiments performed in greenhouses between Sept. 1989 and May 1990.
Abstract: «Karls» and «Rosana», two Boston-type lettuce (Lactuca saliva L.) cultivars, were subjected to various light treatments in greenhouses equipped with one of two propane heating systems. Photoperiods of 16, 20, 24, or 24 hours for 2 weeks after transplanting and then 16 hours (2416) and photosynthetic photon flux of 50 or 100 μmol.m -2 .s -1 provided by supplementary lighting (high-pressure sodium vapor lamps) were compared to natural light during four experiments performed in greenhouses between Sept. 1989 and May 1990. Using supplementary lighting resulted in significant increases in biomass (≤270%),head firmness, and tipburn incidence and decreases in production cycle length (≃30%)
76 citations
TL;DR: Winter was the most favourable growing season for both types of lettuce but mycorrhizal plants cultivated in other seasons different from winter achieved higher or similar shoot biomass than their respective non-inoculated controls in winter.
54 citations
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21,056 citations
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01 Jan 1972
TL;DR: The quantitative analysis of plant growth is presented as a probabilistic procedure to estimate the growth rate of various phytochemical barriers to plant growth.
Abstract: The quantitative analysis of plant growth , The quantitative analysis of plant growth , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
1,278 citations
TL;DR: In this article, the spectral energy distributions of the light were used to calculate the flux densities of photosynthetically active radiation (E ), variously defined as: (1) the energy flux in the waveband 400-700 nm; (2) the expected quantum flux (IQF) in waveband 380-710 nm; and (3) the absorbed quantum flux in wave band 400−700 nm, were also calculated.
509 citations
TL;DR: Growth rate predictions from the cabinet work agreed fairly well with observations made in the field, and the faster-growing cultivars had higher net assimilation rates than the others, but the cultivar-temperature interaction was not statistically significant.
Abstract: SUMMARY
Six lettuce cultivars were grown to a dry weight of about 0.2 g per plant at four constant temperatures with high light intensity and ample nutrients. Relative growth rates (RGR) were sigmoidally related to temperature, averaging 0.11 g/g/day at 10 °C and 0.35 g/g/day at 22 °C. The cultivars Cobham Green and Avoncrisp had higher RGRs than the others, but the cultivar-temperature interaction was not statistically significant. Temperature affected both components of RGR, i.e. net assimilation rate and leaf area ratio, about equally: the faster-growing cultivars had higher net assimilation rates than the others. Growth rate predictions from the cabinet work agreed fairly well with observations made in the field.
39 citations