Joaquín Álvarez Hernández

Influence of root temperature on phytoaccumulation of As, Ag, Cr, and Sb in potato plants (Solanum tuberosum L. var. Spunta).

Three consecutive years of field experiments were carried out to investigate the effect of root temperatures induced by the application of mulches for phytoextraction of As, Ag, Cr and Sb using potato plants (roots, tubers, stems and leaflets). Four different plastic covers were used (T1: transparent polyethylene; T2: white polyethylene; T3: white and black coextruded polyethylene; and T4: black polyethylene), taking uncovered plants as control (T0). The different treatments had a significant effect on mean root temperatures (T0 = 16°C, T1 = 20°C, T2 = 23°C, T3 = 27°C and T4 = 30°C) and induced a significantly different response in the As, Ag, Cr and Sb phytoaccumulation. The T3 treatment gave rise to the greatest phytoaccumulation of As, Ag, Cr and Sb in the roots, leaflets and tubers. In terms of the relative distribution of the phytoaccumulated metals (with respect to the total of the plant), As accumulated mainly in the roots and leaflets whereas Ag, Cr and Sb accumulated primarily in the tubers, establishing a close relationship between biomass development of each organ and phytoaccumulation capacity of elements in response to temperature in the root zone. With regard to phytoremediation using the potato plant, it is necessary to ascertain the influence and include the control of the thermal regime of the soil to optimize the phytoextraction of pollutants.

Influence of root temperature on uptake and accumulation of Ni and Co in potato

Summary The impact of root temperature on Ni and Co concentration and accumulation has been studied in organs (roots, tubers, stems and leaves) of Solanum tuberosum L. var. Spunta plants. The response of foliar- and root-urease activity was also determined under the same conditions. Four different polyethylene plastic covers were employed (T1: transparent; T2: white; T3: coextruded black+white; T4: black), using uncovered plants as control (T0). The different treatments had a significant effect on mean root zone temperatures (T0 = 16 °C, T1 = 20 °C, T2 = 23 °C, T3 = 27 °C and T4 = 30 °C) and induced a significantly different response in the Ni and Co distribution in potato organs, since T3 (27 °C) gave higher concentrations of Ni in roots, leaves and tubers. The T1 (20 °C) registered the greatest Co concentration in leaves and roots, while T3 gave higher Co concentrations in tubers. The tubers proved to be the organs with the highest biomass and also the highest Co and Ni accumulation. With respect to the response of the urease activity as Ni-bioindicator, the root urease activity was higher in T1, whereas the leaf urease activity was higher in T3 and T4, coinciding with higher concentrations of leaf Ni. It is necessary to ascertain the relevance and control of the thermal regime of the soil to optimize the phytoextraction (phytoremediation) of elements.

Nitrogen and phosphorus metabolism and yield of capsicum plant (Capsicum annuum L. cv. Lamuyo) in response to increases in NK fertilization

Abstract Capsicum plants were grown under controlled conditions and submitted to individual fertilization with varying rates of NK. N was applied as NH4NO3 (N1: 6 g m‐2, N2: 12 g m‐2, N3: 18 g m‐2and N4: 24 g m‐2) and K as K2SO4 (K1: 4 g m‐2, K2: 8 g m‐2and K3: 12 g m‐2), resulting in 12 treatments of the corresponding crosses between the different rates of N and K. Applying high rates of N and K led to an increase in the absorption and translocation of NO to the shoot, however, the trend of the NR in the two assays studied (NRc and NRi) and that of NH indicate that this latter ion was the main N form assimilated by the plant. The products resulting from this process, mainly proteins, increased with higher N and K rates, which also gave rise to the maximum leaf concentrations of organic and total P forms, while inorganic P was unaffected. The acid phosphatase activity proved to be a good indicator of the nutritional status of P. Finally, yield in Kg plant‐1 was maximum at N3K1, whereas the greatest number of fruits were maximum at the N4K3 rate.Capsicum plants were grown under controlled conditions and submitted to individual fertilization with varying rates of NK. N was applied as NH 4 NO 3 (N 1 : 6 g m -2 , N 2 : 12 g m -2 , N 3 : 18 g m -2 and N 4 : 24 g m -2 ) and K as K 2 SO 4 (K 1 : 4 g m -2 , K 2 : 8 g m -2 and K 3 : 12 g m -2 ), resulting in 12 treatments of the corresponding crosses between the different rates of N and K. Applying high rates of N and K led to an increase in the absorption and translocation of NO to the shoot, however, the trend of the NR in the two assays studied (NRc and NRi) and that of NH indicate that this latter ion was the main N form assimilated by the plant. The products resulting from this process, mainly proteins, increased with higher N and K rates, which also gave rise to the maximum leaf concentrations of organic and total P forms, while inorganic P was unaffected. The acid phosphatase activity proved to be a good indicator of the nutritional status of P. Finally, yield in Kg plant -1 was maximum at N 3 K 1 , whereas the greatest number of fruits were maximum at the N 4 K 3 rate.

Temperature in relation to phosphorus nutrition in Chinese cabbage.

Abstract Chinese cabbage plants [Brassica pekinensis (Lour) Rupr. cv. Nagaoka 50] were cultivated experimentally for two years (1993 and 1994) using a semi‐forcing technique of floating rowcovers, polyethylene (T1), polypropylene (T2), versus no floating row‐covers, control (T0). Five samplings were made, taking four plants per each replication and total phosphorus (P) (Ptotal), inorganic P (Pi), and calculated organic P (Porg) were determined as well as foliar acid phosphatase activity (FAPA). The aerial and root temperatures of the treatments T1 and T2 exceeded those of T0. The Ptotal concentration showed no significant variations with treatment, whereas the Pi concentrations increased in Ti and T2 and Porg decreased in both treatments with respect to T0. The FAPA was influenced a similar way as Pi, raising with temperature. The contents (mg plant‐1) of Ptolal, Pi, and Porg were greater in T1 and T2 than in T0, and this could be due to the fact that the highest temperatures (root and aerial zone) generated by the plastic rowcovers favored the absorption of P, thereby boosting FAPA and the fresh and dry weights, and yield.

Applications in sustainable production

Capsicum plants grown under controlled conditions underwent crossed fertilization with N (four levels) and K (three levels) totalling 12 combination of NK dosages. The plants were sampled throughout their growth cycle and the leaves were analyzed to measure total and soluble Ca and Mg, and their fractions. Soluble Mg showed its lowest leaf level in the treatment N 4 K 3 , whereas the highest value was obtained at N 1 K 3 . Total Mg has the maximum leaf levels at N 1 K 2 , whereas the lowest levels occurred in the treatment N 2 K 1 The various fractions of Mg showed different degrees of importance and in the present study the order of importance was: Pectate-Mg Inorganic-Ca > Pectate-Ca Residual-Ca > Phosphate-Ca.Abstract Capsicum plants grown under controlled conditions underwent crossed fertilization with N (four levels) and K (three levels) totalling 12 combination of NK dosages. The plants were sampled throughout their growth cycle and the leaves were analyzed to measure total and soluble Ca and Mg, and their fractions. Soluble Mg showed its lowest leaf level in the treatment N4K3, whereas the highest value was obtained at N1K3. Total Mg has the maximum leaf levels at N1K2, whereas the lowest levels occurred in the treatment N2K1. The various fractions of Mg showed different degrees of importance and in the present study the order of importance was: Pectate‐Mg<Residual‐Mg<Organic acid anion‐Mg<Organic anion‐Mg<Chlorophyll‐Mg. Soluble Ca showed its lowest leaf level in the treatment N3K3, whereas the highest value was obtained at N4K1. Total Ca has the maximum leaf levels at N4K3, whereas the lowest levels occurred in the treatment N1K2. The increasing NK supply directly or indirectly affects the integration of the ionic forms of Ca in plant tissues as Ca was integrated in proportions which indicated the growing conditions of the crop, with the following order: Oxalate‐Ca > Inorganic‐Ca > Pectate‐Ca ≈ Residual‐Ca > Phosphate‐Ca

Effect of root zone temperature on accumulation of molybdenum and nitrogen metabolism in potato plants

Abstract Changes in root temperature caused by the application of plastic covers were studied in relation to the uptake and content of molybdenum (Mo) in the different organs of potato (Solanum tuberosum L. var. Spunta) plants (roots, tubers, stems, and leaves) and in relation to nitrogen (N) metabolism. For the semi‐forcing technique of mulching, four different covers were used: T 1 (transparent polyethylene), T 2 (white polyethylene), T 3 (coextruded black and white polyethylene), and T 4 (black polythylene). The control treatment had no mulch. The results revealed a positive and significant effect of plastic covers on root temperatures: T 0 = 16°C, T 1 = 20°C, T 2 = 24°C, T 3 = 27°C, T 4 = 30°C. These thermal differences significantly influenced the Mo concentration, particularly in the T 2 and T 3 treatments in the leaves, roots, and tubers. The same temperatures significantly altered N metabolism in both the aerial and underground parts of the plants, and a strong interrelationship was found between Mo and nitrate reductase (NR) activity. The mulching of this crop proved to be a promising technique in phytoremediation.

INFLUENCE OF THERMAL REGIME OF SOIL ON THE SULFUR (S) AND SELENIUM (Se) CONCENTRATION IN POTATO PLANTS

ABSTRACT Three consecutive years of field experiments were carried out to investigate the effect of different root temperatures, induced by the application of mulches on the concentration of sulfur (S) forms (organic-S, total-S and ) and Se in different organs of potato plants (roots, tubers, stems and leaves). Four different plastic covers were used (T1: transparent polyethylene; T2: white polyethylene; T3: white and black coextruded polyethylene, and T4: black polyethylene), using uncovered soil as control (T0). The different treatments had a significant effect on mean root temperatures (T0 = 16°C, T1 = 20°C, T2 = 23°C, T3 = 27°C and T4 = 30°C) and induced a significantly different response in the S forms and Se concentration, showing the T3 treatment (27°C) the greatest concentration of total S and organic S in the stems and leaflets. The Se reached higher levels in the roots and tubers in T3. With regard to possibilities in phytoremediation, it is necessary to control the thermal regime of the soil to optimize the accumulation of elements.

THE INFLUENCE OF THE ROOT ZONE TEMPERATURES ON THE PHYTOEXTRACTION OF BORON AND ALUMINIUM WITH POTATO PLANTS GROWING IN THE FIELD

ABSTRACT The effect of different root zone temperatures on the concentration and content of B and Al in potato plants was examined using four different treatments of plastic mulches: T1: transparent polyethylene; T2: white polyethylene; T3: coextruded black and white polyethylene; T 4: black polyethylene. An open-air treatment (T0) was used as control. The results showed significantly positive effects of the plastic covers on the root-zone temperatures: T0 = 16°C, T1 = 20°C, T2 = 23°C, T3 = 27°C, T4 = 30°C. These different soil temperature conditions significantly altered the B concentrations, with T3 promoting the greatest concentrations and phytoaccumulation. The root zone temperature treatments induced higher concentrations and accumulation of Al in the T2 and T3 treatments in the roots, tubers, and leaves. The T2 and T3 lead to high levels of pectins in the roots, tubers, and leaves. This appears to reflect a possible mechanism of tolerance to the high Al and B concentrations in the analysed organs.

THE RESPONSE OF SHOOT ACCUMULATION OF TRACE ELEMENTS IN CHINESE CABBAGE TO MICROCLIMATE MODIFICATION

In three consecutive years of field experiments (1994–96), three different environmental conditions for the growth of Chinese cabbage (Brassica pekinensis (Lour) Rupr. cv. Nagaoka 50) were established by using two cover treatments (T 1 and T 2) and a control uncovered cultivation (T 0). The T 1 [50 μm polyethylene cover; 20°C air temperature; 61.9% relative moisture; 207 W m−2 irradiance] and T 2 [a 17 gm−2 non-woven fleece; 18°C; 63.4%; 205 Wm−2] gave rise to differences in environmental conditions with respect to T 0 [14°C; 57.5%; 237 Wm−2]. We analysed chloride (Cl), barium (Ba), rubidium (Rb) and tin (Sn) in the whole tops of experimental plants. Chloride removal was high for Brassica pekinensis but considerably lower for Rb, giving intermediate values for Ba and Sn. The influence of environmental factors under T 1 increased trace-element removal and enhanced the usefulness for phytoremedation.

Root zone temperature affects the phytoextraction of Ba, Cl, Sn, Pt, and Rb using potato plants (Solanum tuberosum L. var. Spunta) in the field.

Three consecutive years of field experiments were conducted to investigate how different root-zone temperatures, manipulated by using different mulches, affect the phytoextraction of Ba, Cl, Sn, Pt and Rb in different organs of potato plants (roots, tubers, stems and leaves). Four different plastic covers were used (T1: transparent polyethylene; T2: white polyethylene; T3: white and black coextruded polyethylene, and T4: black polyethylene), using uncovered plants as control (T0). The different treatments had a significant effect on mean root zone temperatures (T0 = 16°C, T1 = 20°C, T2 = 23°C, T3 = 27°C and T4 = 30°C) and induced a significantly different response in Ba, Cl, Sn, Pt and Rb concentration and accumulation. The T3 treatment gave rise to the greatest phytoextraction of Ba, Pt, Cl and Sn in the roots, leaflets and tubers. In terms of the relative distribution of the phytoaccumulated elements (as percentage of the total within the plant), Pt and Ba accumulated mainly in the roots whereas Rb, Sn and Cl accumulated primarily in tubers, establishing a close relationship between the biomass development of each organ and phytoaccumulation capacity of metals in response to temperature in the root zone.