Vegetative Growth Of Tomato Research Articles

Relationship between Cold Tolerance during Seed Germination and Vegetative Growth in Tomato: Germplasm Evaluation

Cold tolerance (CT) of 31 tomato accessions (cultivars, breeding lines, and plant introductions) representing six Lycopersicon L. sp. was evaluated during seed germination and vegetative growth. Seed germination was evaluated under temperature regimes of 11 ± 0.5 °C (cold stress) and 20 ± 0.5 °C (control) in petri plates containing 0.8% agar medium and maintained in darkness. Cold tolerance during seed germination was defined as the inverse of the ratio of germination time under cold stress to germination time under control conditions and referred to as germination tolerance index (TIG). Across accessions, TIG ranged from 0.15 to 0.48 indicating the presence of genotypic variation for CT during germination. Vegetative growth was evaluated in growth chambers with 12 h days/12 h nights of 12/5 °C (cold stress) and 25/18 °C (control) with a 12 h photoperiod of 350 mmol.m-2.s-1 (photosynthetic photon flux). Cold tolerance during vegetative growth was defined as the ratio of shoot dry weight (DW) under cold stress (DWS) to shoot DW under control (DWC) conditions and referred to as vegetative growth tolerance index (TIVG). Across accessions, TIVG ranged from 0.12 to 0.39 indicating the presence of genotypic variation for CT during vegetative growth. Cold tolerance during vegetative growth was independent of plant vigor, as judged by the absence of a significant correlation (r = 0.14, P > 0.05) between TIVG and DWC. Furthermore, CT during vegetative growth was independent of CT during seed germination, as judged by the absence of a significant rank correlation (rR = 0.14, P > 0.05) between TIVG and TIG. A few accessions, however, were identified with CT during both seed germination and vegetative growth. Results indicate that for CT breeding in tomato, each stage of plant development may have to be evaluated and selected for separately.

Comparison of salt tolerance during seed germination and vegetative growth in tomato by QTL mapping

The purpose of this study was to determine the genetic relationship between salt tolerance during seed germination and vegetative growth in tomato by comparing quantitative trait loci (QTLs) which confer salt tolerance at these two developmental stages. A salt-sensitive Lycopersicon esculentum line (NC84173; maternal and recurrent parent) was hybridized with a salt-tolerant accession (LA722) of Lycopersicon pimpinellifolium, and BC1and BC1S1populations were developed. The BC1population was used for RFLP mapping and the BC1S1population for evaluation of salt tolerance during germination and vegetative growth. The results indicated the presence of a small but significant correlation (r = -0.22, p < 0.05) between rate of seed germination and the percentage of plant survival under salt stress. Seven and five QTLs were identified for salt tolerance during seed germination and vegetative growth, respectively. While in most cases the location of QTLs for germination was different from that for vegetative growth, there were some coincidences in QTL locations; this was consistent with the small phenotypic correlation observed between the two traits. The overall results indicated that, in these tomato genetic materials, salt tolerance during seed germination was independent of that during vegetative growth. However, simultaneous improvement of tolerance at the two developmental stages should be possible through marker-assisted selection and breeding.Key words: Lycopersicon esculentum, L. pimpinellifolium, salt tolerance, seed germination vegetative growth, restriction fragment length polymorphism (RFLP), quantitative trait loci (QTLs).

Comparison of salt tolerance during seed germination and vegetative growth in tomato by QTL mapping

The purpose of this study was to determine the genetic relationship between salt tolerance during seed germination and vegetative growth in tomato by comparing quantitative trait loci (QTLs) which confer salt tolerance at these two developmental stages. A salt-sensitive Lycopersicon esculentum line (NC84173; maternal and recurrent parent) was hybridized with a salt-tolerant accession (LA722) of Lycopersicon pimpinellifolium, and BC1 and BC1S1 populations were developed. The BC1 population was used for RFLP mapping and the BC1S1 population for evaluation of salt tolerance during germination and vegetative growth. The results indicated the presence of a small but significant correlation (r = -0.22, p < 0.05) between rate of seed germination and the percentage of plant survival under salt stress. Seven and five QTLs were identified for salt tolerance during seed germination and vegetative growth, respectively. While in most cases the location of QTLs for germination was different from that for vegetative growth, there were some coincidences in QTL locations; this was consistent with the small phenotypic correlation observed between the two traits. The overall results indicated that, in these tomato genetic materials, salt tolerance during seed germination was independent of that during vegetative growth. However, simultaneous improvement of tolerance at the two developmental stages should be possible through marker-assisted selection and breeding.Key words: Lycopersicon esculentum, L. pimpinellifolium, salt tolerance, seed germination vegetative growth, restriction fragment length polymorphism (RFLP), quantitative trait loci (QTLs).

Absence of a genetic relationship between salt tolerance during seed germination and vegetative growth in tomato

AbstractTwo approaches were used to determine the relationship between salt tolerance during seed germination and vegetative growth in tomato. First, F4 progeny families of a cross between a breeding line, ‘UCT5’ (salt sensitive at all developmental stages), and a primitive cultivar, ‘PI 174263’ (salt tolerant during germination and vegetative growth), were evaluated in separate experiments for salt tolerance during germination and vegetative growth. There were significant differences among the F4 families in both the rate of seed germination and the plant growth (dry matter production) under salt stress. There was, however, no significant correlation between the ability of seeds to germinate rapidly and the ability of plants to grow under salt stress. In the second approach, selection was made for rapid germination under salt stress in an F2 population of the same cross and the selected progeny was evaluated for salt tolerance during both germination and vegetative growth. The results indicated that selection for salt tolerance during germination significantly improved germination performance under salt stress; a realized heritability estimate of 0.73 was obtained. Selection for salt tolerance during germination, however, did not affect plant salt tolerance during vegetative growth; there was no significant difference between the selected and unselected progeny based on either absolute or relative growth under salt stress. Obviously, in these genetic materials, salt tolerance during germination and vegetative growth are controlled by different mechanisms. Thus, to develop tomato cultivars with improved salt tolerance, selection protocols that include all critical developmental stages would be desirable.

Effect of N Source on Photosynthesis and Plant Dry Matter Yield of Tomato

The objective of this study was to determine if winter legume or grain cover could support net photosynthesis (Pn) and plant dry matter production comparable to recommended rate of synthetic N. The following winter/spring fertility treatments were applied: 1) 0 N winter/0 N spring, 2) 0 N winter/90 kg·ha–1 N spring, 3) 0 N winter/180 kg·ha–1 N spring, 4) 0 N winter+abruzi rye/0 N spring, 5) 0 N winter+hairy vetch/0 N spring, and 6) 0 N winter+crimson clover/0 N spring. `Mountain Pride' tomato was planted in all plots in spring. Plant dry weight and Pn were measured at flowering, fruiting and prior to senescence. The highest Pn (22.78 μmol CO2/m2 per s) and leaf dry weight (115.2 g/plant) were obtained at fruiting, while highest branch dry weight (194.5 g/plant) occurred prior to senescence. There was significant increase in plant dry weight during reproductive growth phase. Tomato plants receiving supplemental N from crimson clover or hairy vetch had Pn and plant dry weight comparable to those receiving synthetic N. The results of this study indicated that legume cover crops were as effective as commercial N fertilizer for supporting photosynthesis and vegetative growth of tomato.

Genetic basis of physiological traits related to salt tolerance in tomato, Lycopersicon esculentum Mill.

AbstractGenetic relationships between salt tolerance and expression of various physiological traits during vegetative growth in tomato, Lycopersicon esculentum Mill., were investigated. Parental, F1, F2 and backcross progeny of a cross between a salt tolerant (PI174263) and a salt sensitive tomato cultivar (‘UCT5’) were evaluated in saline solutions with electrical conductivity of 0.5 (non‐stress) and 20 dS/m (salt stress). Absolute growth, relative growth, tissue ion content, leaf solute potential and the rate of ethylene evolution were measured. Growth of both parents was reduced under salt stress; however, the reduction was significantly less in PI174263 than ‘UCT5’, suggesting greater salt tolerance of the former. Under salt stress, leaves of PI174263 accumulated significantly less Na+ and Cl− and more Ca2+ than leaves of ‘UCT5’. Across parental and progeny generations, growth under salt stress was positively correlated with leaf Ca2+ content and negatively correlated with leaf Na+ content. In contrast, no correlation was observed between growth and either leaf solute potential or the rate of ethylene evolution under salt stress. Generation means analysis indicated that under salt stress both absolute and relative growth and the Na+ and Ca2+ accumulations in the leaf were genetically controlled with additivity being the major genetic component. The results indicated that the inherent genetic capabilities of PI174263 to maintain high tissue Ca2+ levels and to exclude Na+ from the shoot were essential features underlying its adaptation to salt stress and that these features were highly heritable. Thus, tissue ion concentration may be a useful selection criterion when breeding for improved salt tolerance of tomato using progeny derived from PI174263.

Genetic analysis of salt tolerance during vegetative growth in tomato, Lycopersicon esculentum Mill.

AbstractBreeding for salt tolerance in tomato has been impeded by insufficient knowledge of the genetic control of tolerance. The genetic basis of salt tolerance during vegetative growth was investigated by growing a salt‐tolerant (PI174263) and a salt‐sensitive tomato cultivar (UCT5) and their F1, F2 and backcross progeny in saline solutions with electrical conductivity of 0.5 (control) and 20 dS/m (salt‐stress). The relative salt‐tolerance of each generation was determined as the percentage of growth (i.e. dry matter production) under salt‐stress relative to growth under control conditions. In all generations, shoot growth was significantly reduced by salt stress. The reduction was largest in UCT5 (56.1%) and smallest in the F1 (27.4%), followed by PI174263 (32.3%). Analysis of the absolute and relative growth under salt‐stress indicated that genes contributing to vigour might be different from genes conferring tolerance. Generation means analyses of the absolute and relative growth indicated that the majority of the genetic variation among generations were due to simple (additive and dominance) genetic effects; nonallelic interactions, although significant, were far less important. Partitioning of the total genetic variance by weighted least‐square regression analysis and variance component analysis indicated that 88% or more of the variation was due to additive genetic effects. A moderate estimate of narrow sense heritability (0.49 ± 0.09) was obtained for shoot DW under salt‐stress treatment. The results indicate that tomato salt‐tolerance during vegetative growth can be improved by breeding and selection.

Genetic Analysis of Salt Tolerance during Vegetative Growth in Tomato

Breeding for salt tolerance in tomato (Lycopersicon esculentum Mill.) has been restricted by insufficient knowledge of the genetic control of tolerance. The genetic basis of salt tolerance during vegetative growth was investigated by growing a salt tolerant (PI174263) and a salt sensitive tomato cultivar (UCT5) and their F1, F2, and backcross progeny in saline solutions with electrical conductivity of 0.5 (control) and 20 dS·m–1 (salt-stress). The relative salt tolerance of each generation was determined as the percentage of growth (i.e., dry matter production) under salt-stress relative to growth under control conditions. In all generations, shoot growth was significantly reduced by salt-stress. The reduction was largest in UCT5 (56.1%) and smallest in the F1 (27.4%) followed by PI174263 (32.3%). Analysis of the absolute and relative growth under salt-stress indicated that genes contributing to vigor might be different from genes conferring tolerance. Generation means analyses of the absolute and relative growth indicated that the majority of the genetic variation among generations were due to simple (additive and dominance) genetic effects; nonallelic interactions, although significant, were far less important. Partitioning of the total genetic variance by weighted least square regression analysis and variance component analysis indicated that 88% or more of the variation were due to additive genetic effects. A moderate estimate of narrow sense heritability (0.49 ± 0.09) was obtained for shoot dry weight under salt-stress treatment. The results indicate that tomato salt tolerance during vegetative growth can be improved by breeding and selection.

Genetic Basis of Physiological Traits Related to Salt Tolerance in Tomato

Genetic relationships between salt tolerance and expression of various physiological traits during vegetative growth in tomato were investigated. Parental, F1, F2, and backcross progeny of a cross between a salt tolerant (PI174263) and a salt sensitive cultivar (UCT5) were evaluated in saline solutions with electrical conductivity of 0.5 (non-stress) and 20 dS·m–1 (salt-stress). Absolute growth, relative growth, tissue ion content, leaf solute potential and the rate of ethylene evolution by leaf petioles were measured. Growth of both parents were reduced under stress, however, the reduction was significantly less in PI174263 than UCT5 suggesting greater salt tolerance of the former. Under salt-stress, PI174263 accumulated in the leaf significantly less Na+ and Cl– and more Ca2+ than UCT5. The F1 hybrid performed intermediate relative to parents and the backcross populations approached recurrent parents in both growth response and ion accumulation. In all generations, leaf solute potential decreased and the rate of ethylene evolution increased under salt-stress, however, there were little or no differences among generations under either treatment. Across generations growth under salt-stress was positively correlated with Ca2+ and negatively correlated with Na+ accumulation in the leaf. In contrast, growth was not correlated with either leaf solute potential or the rate of ethylene evolution. Generation means analysis indicated that Na+ and Ca2+ accumulations were genetically controlled with additivity being the major genetic components. The results indicated that the inherent genetic capabilities of PI174263 to maintain high tissue Ca2+ levels and to exclude Na+ from shoot were essential features underlying its adaptation to salinity. Thus, tissue ion concentration may be a useful selection criterion when breeding for improved salt tolerance of tomato using progeny derived from PI174263.

Soil management for irrigated vegetable production. I. The growth of processing tomatoes following soil preparation by cultivation, zero-tillage and an in situ-grown mulch

A sequence of lettuce and tomato crops was grown in a field experiment on a sandy loam soil in order to study the relationship between soil tillage and plant growth under the near optimal water and nutrient conditions which are characteristic of vegetable production. This paper describes the performance of processing tomato crops, grown over two seasons under a range of soil management systems. The soil management systems included a cultivated and a zero-tillage treatment, as well as a zero-tillage treatment which followed a crop of subterranean clover (Trifoliurn subterraneum L.). The subterranean clover was sown in autumn and senesced in early summer to form an in-situ mulch. The bulk density of the soil in the zero-tillage treatment was high, and this was associated with a large reduction in vegetative growth, compared with the cultivated treatment. The bulk density of the soil was also high in the treatment where the subterranean clover was grown, but the vegetative growth of tomatoes was equal to that in the cultivated treatment. Despite the large differences in vegetative growth among treatments, there was no significant difference in the fruit yield. These results show that processing tomatoes can be successfully grown under zero-tillage when irrigation and fertilizer are well managed, and that vegetative growth and fruit yield are poorly correlated. The in-situ mulch of subterranean clover improved the physical conditions of the soil compared to the zero-tillage treatment, successfully controlled weeds and reduced soil erosion, but at the cost of having land out of production during the winter.

Effects of Salt Stress Applied in Balanced Nutrient Solutions at Several Stages during Growth of Tomato

Deleterious effects of salt stress on vegetative growth of tomato were most pronounced when plants were exposed to saline conditions during the early seedling stage. Growth rates remained severely restricted following removal of stress during this period, but plants stressed at later times resumed growth at rates similar to control values soon after they were returned to base nutrient solutions. While bud and flower formation were delayed by salt stress, the effect followed the previous trend and was most pronounced when plants were stressed during early vegetative growth. There were no indications that tomato declined in salt tolerance at the time of budding or flowering. The increase in water content of control plants during the early days of growth suggests that a rise in succulence is to be expected under nonstress conditions. However, imposition of stress during this period caused a marked decrease of water in the tissues, and contrary to the normal state, succulence declined during the sensitive see...