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A study was conducted with Lotus creticus and Limonium cossonianum to analyze the influence of irrigation regime in nursery on the dynamics of root development after being transplanted with minimum management conditions. Plants were pot-grown in a greenhouse located at the southeastern Mediterranean coast of Spain (37°47′N, 0°54′W). Each plant was potted into 625-mL plastic pot filled with a 1 silica sand medium: 1 peat (v/v) mixture amended with osmocote plus (3.7 g•kg-1 substrate). Drip irrigation was used, with a 2-L•h-1 emitter per plant. Three irrigation treatments were utilized: T6, plants watered 6 days a week at the water-holding capacity (leaching ≈20% of the applied water); T3, plants watered 3 days a week; and T2, plants watered twice a week. T3 and T2 plants received amounts of water at ≈50% and ≈30%, respectively, of T6 plants troughout the nursery period (3 months for Lotus and 45 days for Limonium). After nursery period, plants were transplanted into transparent containers (round acrylic tubes 8 cm in diameter and 100 cm tall) filled with silt loam texture soil, and just one establishment irrigation was applied (30 mm). Containers were covered with a black plastic sheet and isolating material to prevent light influencing and becoming heated. There were three replications. Plant root and top growth were measured every 3 days for 1 month. Results indicate that those plants that were less watered in nursery showed a greater and faster root development especially where depth was concerned. Lotus plants root growth, for the top 20 cm of soil, were not significantly affected by irrigation treatments; between 20 and 40 cm deep, T2 plants at 12 days after transplanting (DAT) had 2.8- and 9.1-times greater root length (RL) than T3 and T6 plants, respectively. At 30 DAT, T2 plants had 1.7- and 6.2-times higher RL than T3 and T6, respectively. Under 40-cm deep (where infiltration of the establishment irrigation water was very limited), only T2 plants developed roots. There was no plant top growth throughout this period. Limonium plants exhibited notably lower root development (≈1/5) than Lotus plants. In the top 15 cm of soil, Limonium plants RL were not significantly affected by irrigation treatment; between 15 and 30 cm deep, T2 and T3 plants, at 10 DAT, had 2.2-times longer RL than T6 plants, and at 30 DAT, T2 plants had 1.4- and 2.1-times greater RL than T3 and T6 plants, respectively. Below 30 cm, only T2 plants developed roots and, even so, very few ones. For this period, a slight plant top growth was observed, there being no significant differences among irrigation treatments. Research suported by CICYT grant AGF-96-1136-C02-02.
The appearance of blossom-end rot (BER) in tomato is related to a decrease in the absorption and translocation of Ca due to excessive salinity in the soil solution. An experiment was conducted to investigate the effects of calcium nitrate (NT), EDTA-Ca (ED) and Aminoquelant-Ca (AQ)—a product containing Ca, B and protein hydrolisate—on the yield and incidence of BER when applied to the leaves of tomato (Lycopersicon esculentum Mill. `Durinta') grown in the open with a drip irrigation using saline water from a well (mean ECw 5.2 dS·m–1). The three calcium treatments and control were replicated four times, with 12 plants per replication, in a completely randomized design. Although yield per plant was higher with AQ, the difference was not statistically significant. Fewer fruit were affected by BER after treatment with ED and AQ than with NT and in the control. Leaf Ca concentration did not differ significantly between treatments. However, leaf B concentration was higher after treatment with AQ. Fruit Ca and B concentrations did not differ significantly in any treatment. The total free amino acids content in leaves was higher after AQ treatment than in the other treatments and control, although no significant difference was observed between the treatments in the fruit.
A study was conducted with Limonium cossonianum O. Kuntze to analyze the influence of irrigation regime in nursery on the dynamics of root development after being transplanted with minimum management conditions. Plants were potgrown in a greenhouse. Each plant was potted into 625-mL plastic pot filled with a 1 silica sand medium: 1 peat mixture (v/v) amended with osmocote plus (3.7 g•kg-1 substrate). Drip irrigation was used with a 2-L•h-1 emitter per plant. Two irrigation treatments were used: T3, plants watered 6 days a week at the water-holding capacity (leaching 20% of the applied water) and T1, plants watered twice a week, receiving an amount of water at 30% of T3 plants troughout the nursery period (45 days). After nursery period, plants were transplanted in the open air at the southeast Mediterranean coast of Spain (37°47′N, 0°′54′W), and just one establishment irrigation was applied (50 mm). There were three replications. Plant root and top growth were measured weekly for 13 months. For the root dynamics study, minirhizotrons were used. Acrylic tubes, 2 m long and 80 mm in outside diameter, were placed at a inclination of 24°, reaching a total depth of 160 cm. The evolution of the root length density (RLD) was measured by seven 23-cm-deep soil layers. Results indicate that those plants that were less watered in nursery showed a greater RLD for the whole soil profile. Plants root growth for the top 46 cm of soil were not significantly affected by irrigation treatments; between 46 and 115 cm deep, T1 plants showed greater RLD than T3 (average values of 0.6 vs. 0.3 cm•cm-3); and under 115-cm deep (where root growth was more limited), there were not significant differences. For the first 6 months, a important plant top growth was observed, there being no significant differences among irrigation treatments. Research suported by CICYT grant AGF-96-1136-C02-02.
The dendrometer has been proposed as a sensitive plant water indicator based on stem growth. However, studies including dendrometers have been mainly focused on fruit trees and less attention has been paid to ornamental shrubs (small plants). In the study described here, stem dendrometers were used to ascertain whether there is any relationship between water status and dendrometric indices in potted ornamental shrubs (1 to 2 cm diameter). For this purpose, three Mediterranean shrubs (Pittosporum tobira, Callistemon citrinus, and Rhamnus alaternus) were studied under water stress recovery conditions in winter, spring, and early summer. At the end of the experiment, an extreme water stress treatment, which resulted in plant death (August) was also studied. Stem diameter variations [maximum and minimum daily stem values (MXDS and MNDS, respectively), maximum daily shrinkage (MDS), and stem growth rate (SGR)], daily evapotranspiration (daily plant ET), and leaf water potential (Ψleaf) parameters were considered throughout the experiment. A regression analysis between dendrometric indices and daily plant ET showed that MXDS and MNDS were sensitive under water stress recovery conditions, especially in severe environmental conditions (spring and summer). The SGR in C. citrinus, the MDS in P. tobira, and both indices in R. alaternus were seen to be sensitive during the stress to death period. Although more studies are needed, the results confirm that the use of dendrometers in small plants may be useful to provide continuous and automated registers of the plant water status under different substrate water content and climatic conditions. However, the response of these indices may imply moderate water stress.