Influence Of Root Zone Temperature Research Articles

Influence of root-zone temperature on growth and nitrogen fixation in three Iranian grasspea landraces

In order to study the effects of different root-zone temperature (RZT) and two Rhizobium leguminosarum strains (originating from cold area and temperate area) on some grasspea (Lathyrus sativus) landraces (Ardabil, Shahrekord, and Zanjan) of Iran, an experiment was conducted in a controlled-environment chamber. In this experiment, four root-zone temperatures (5, 10, 15, and 25°C) and a constant air temperature were considered. Results showed that there were differences among the grasspea landraces for nodulation and nitrogen fixation, growth and development, and dry matter. Low RZT reduced growth, nodulation, and nitrogen fixation in grasspea landraces. Strains had different effects on landraces. Inoculated plants with strain originating from cold areas produced the most nodule number, and plant nitrogen concentration at 15°C RZT, whereas inoculated plants with strain originating from temperate area produced the most nodule number, and plant nitrogen concentration at 25°C RZT. Nodulation, nitrogen fixation, and nitrogenase activities of inoculated plants with a strain originating from cold areas in inoculated plants were higher at low temperature than in inoculated plants with a strain originating from temperate areas. This experiment also showed that grasspea production is not likely to be successful when RZT is below 10°C, especially during vegetative development. Therefore, in the zones where soil temperature is greater than 10°C RZT, grasspea landraces have normal growth and produce average yields.

Effects of root zone temperature and paraquat in the induction of oxidative stress in Trichosanthes cucumerina L.

We investigated the influence of root zone temperature (RZT) and the aerial application of paraquat on stress defence mechanisms of Trichosanthes cucumerina L. To achieve this objective, T. cucumerina cv Green was grown with roots at 25 and 30°C root zone temperature and maintained at 20 ± 1°C air temperature in a growth chamber. These RZT and air temperature had earlier been shown to favor growth and fruit production in T. cucumerina. Plants at each RZT were subjected to paraquat treatment (+P) and without paraquat treatment (−P). Paraquat (0.2 mmol/L) was applied as aerial spray. Results showed that the individual main effects of RZT and paraquat treatments significantly affected the chlorophyll fluorescence and gas exchange parameters, while the interaction of both treatments had no significant effect. Results showed that the total phenolics and ascorbic acid contents of T. cucumerina at 30°C were significantly higher than at 25°C. The T. cucumerina plants in +P treatment recorded significantly lower maximum photochemical efficiency (Fv/Fm), net photosynthesis (A), transpiration rate (E), intercellular CO2 concentration (Ci) and stomatal conductance (g1) compared to untreated plants. Also, plants raised at 30°C recorded significantly higher Fv/Fm, A, E, Ci and g1 compared to plants raised at 25°C. Plants that were sampled at 48 h after paraquat treatment recorded a higher degree of oxidative damage compared to those sampled at 24 h after treatment. We showed that the degree of damage suffered by T. cucumerina, when treated with paraquat either at 25 or 30°C RZT was similar at 48 h after treatment. We concluded that either at 25 or 30°C, exposure of T. cucumerina to paraquat would impose the same degree of oxidative damage.

The influence of root-zone temperature on growth of Betula pendula Roth.

We have examined shoot and root growth and the concentration of carbohydrates in seedlings of a northern (67°N) and a southern (61°N) ecotype of Betula pendula Roth. cultivated at root-zone temperatures of 2, 6, 12 and 17°C. Three hydroponic experiments were conducted in controlled environments. We used three different pretreatments before seedlings were subjected to the experimental temperature treatments. Actively growing seedlings that were acclimated to the hydroponic solution for 3 weeks at a root temperature of 17°C, continued to grow at all the experimental temperatures, with an expected increase in growth from 2 to 17°C. However, if we started with ecodormant cold stored plants or used seedlings grown actively in perlite, no growth was observed at 2°C and only minor growth was found at 6°C. The highest root temperature always produced the best growth. The concentration of nonstructural carbohydrates was higher in seedlings grown at 2°C than at 17°C, and this is probably due to extensive incorporation of carbohydrates into cell walls and other structural elements at 17°C. We found no evidence for differences between the two ecotypes in root growth, in timing of bud burst, but shoot growth terminated in the northern ecotype in the first experiment because the natural photoperiod was below the critical value. Our study highlights the importance of post-transplantation stress (planting check) related to root growth, and that root threshold temperatures may change according to the way plants are pretreated.

The influence of root zone temperature on growth and flavour precursors in Allium cepa L.

SummaryThe effects of changing root zone temperature (RZT) while maintaining a constant foliar temperature were tested. ‘Granex 33’ onions (Allium cepa L.) were grown at RZTs of 12°C (± 3.0°C), 21°C (± 0.5°C) (control), or 34°C (± 0.7°C) while maintaining the air temperature at 21°C (± 0.5°C). Plants were harvested at maturity and bulbs evaluated for their growth and flavour characteristics. Bulb fresh weight was highest at an RZT of 21°C and lowest for plants grown at other RZTs. Total bulb-S was no different for the 12°C and 21°C treatments, but was significantly lower for bulbs grown at an RZT of 34°C. Bulb soluble solids contents and total pyruvic acid (pungency) levels responded similarly, increasing between 12°C and 21°C, and falling in the 34°C treatment. Concentrations of trans-S-1-propenyl-L-cysteine sulphoxide, and two peptide intermediates, 2-carboxypropyl glutathione and -glutamyl propenyl cysteine sulphoxide were highest at 21°C, and lowest at 34°C. The adverse affect of the high RZT (34°C) treatment was significant, leading to short, highly-branched roots and was clearly detrimental to the growth and development of onion plants, as well as reducing sulphur allocation to the flavour biosynthetic pathway.

The Influence of Root Zone Temperature on Photosynthetic Acclimation to Elevated Carbon Dioxide Concentrations

Soybean (Glycine max‘Clark’) was grown from germination to 21 d after sowing (DAS) at ambient (∼360 μmol mol−1) or elevated (∼720 μmol mol−1) carbon dioxide (CO2) at either one of two soil temperatures, 25 or 30 °C to determine the influence of root zone temperature on root growth and photosynthetic stimulation at ambient and elevated concentrations of carbon dioxide. Although the photosynthetic rate became less stimulate over time, a significant stimulation of whole plant photosynthesis and plant dry weight was observed at the elevated CO2concentration during the experimental period irrespective of soil temperature. At neither carbon dioxide concentration did the warmer soil temperature (30 °C) stimulate whole plant growth compared to a soil temperature of 25 °C, but it did increase root growth relative to shoot (top) growth with a subsequent increase in root/shoot ratio. Increasing soil temperature at either carbon dioxide concentration also significantly stimulated whole plant photosynthetic rate. However, the degree of stimulation was reduced with time irrespective of carbon dioxide concentration so that at 21 DAS no difference in photosynthesis between ambient and elevated soil temperatures was observed. Data from this experiment indicate that for soybean, a higher soil temperature stimulates root/shoot ratio and enhances photosynthetic response to elevated carbon dioxide in the short-term (i.e. days), but increasing root/shoot ratios does not provide a satisfactory explanation of long-term stimulation of photosynthesis at elevated levels of carbon dioxide.

Effects of root zone temperature on root initiation and elongation in red pine seedlings

The influence of root zone temperature on root initiation, root elongation, and soluble sugars in roots and shoots was investigated in a glasshouse using 2-0 red pine (Pinusresinosa Ait.) seedlings lifted from a northern Minnesota nursery. Seedlings were potted in a sandy loam soil and grown in chambers where root systems were maintained at 8, 12, 16, or 20 °C for 27 days; seedling shoots were exposed to ambient glasshouse conditions. Total new root length was positively correlated with soil temperature 14, 20, and 27 days after planting, with significantly more new root growth at 20 °C than at other temperatures. The greatest number of new roots occurred at 16 °C; the least, at 8 °C. Total soluble sugar concentrations in stem tissue decreased slightly as root temperature increased. Sugar concentrations in roots were similar at all temperatures. The results suggest that root elongation is suppressed more than root tip formation when red pine seedlings are exposed to the cool soil temperatures typically found during spring and fall outplanting.

Influence of root-zone temperature on growth, development and yield of cucumber plants cv. Toska

In a first experiment, cucumber transplants (cucumis sativa L. cv. Toska) were grwon at five root-zone temperatures (RZT) ranging from 12° to 36°C. Maximum shoot growth and total leaf area were obtained at 24° and 30°C (RZT). In a second experiment, cucumber transplants were submitted to five RZT (12, 18, 24, 30 and 36°C) and five night air temperatures (NAT) that were maintained either constant at 9°, 13° and 17°C or splitted (in two halfs) at midnight (17°/12°C, 17°/9°C). Root-zone warming to 24° or 30°C increased cucumber plant growth and leaf development, but did not compensate completely the loss of productivity induced by low NAT. Split-night temperature had greater effects under the lowest NAT (17°/9°C) and at high RZT (24° or 30°C). In a third experiment, soil warming caused large increase in yields when cucumber plants were grown in the spring, but had very little effects in the fall.

The influence of root zone temperature on phosphorus nutrition of sugarbeet seedlings

The influence of root zone temperature on phosphorus nutrition of sugarbeet seedlings

EFFECT OF ROOT ZONE TEMPERATURES ON CORN LEAF MORPHOLOGY

Corn plants were grown at constant root zone temperatures of 15°, 20°, and 25 °C using sand culture in the greenhouse. Stages of development were defined, using as a basis the appearance of leaf tips from the whorl, so that morphologically similar plants grown at different root zone temperatures could be compared.The time intervals required by the corn plants to reach specific stages of development increased substantially with decreasing temperatures. The total dry weights of the plants at specified stages of development decreased significantly with increasing temperatures. Plants grown at 25° produced on the average 1.7 leaves more than those grown at 15 °C prior to tassel formation. Lamina lengths and dry weights decreased with increasing temperatures. Lamina widths and areas were greatest at 20 °C. The narrowest laminae were produced by plants grown at 15° and smallest lamina areas at 25 °C. While the diameters of one cell type in the laminae were not affected by temperature, the lengths of two other cell types decreased significantly with increasing temperatures.The variations in morphological characteristics of leaf laminae were interpreted on the premise of a direct influence of root zone temperature on the shoot meristem.

The Influence of Root Zone Temperature on the Growth and Contents of Phosphorus and Anthocyanin of Corn

AbstractIn a greenhouse experiment corn plants were grown in sand cultures using a complete nutrient solution in which only the P level varied. Root zone temperatures of 15°, 20°, and 25°C. were used in this experiment. In addition, 2 weeks after emergence, a number of plants were subjected to a sudden change in root zone temperature. The dry weight yield and the P content of the tops and the roots and the anthocyanin content of the tops were determined at 2 and 3 weeks.Low root zone temperature severely restricted the growth of young corn plants. High P levels never fully counteracted this harmful effect. It was likely that reduced P uptake at low root zone temperature was caused primarily by a depression in root growth, induced by the low root zone temperature. Anthocyanin synthesis was stimulated by both a low root zone temperature and a low P level in the nutrient solution indicating that purpling of corn is not necessarily an indication of P deficiency.