A comparison of potato seed tuber yields in beds,pots and hydroponic systems

The objective of this study was to compare potato seed tuber production of cvs. Monalisa and Agata growing in beds, pots or hydroponics, with either single or staggered harvests. All culture systems were established in plastic sheeting-covered greenhouses protected with an anti-aphid network. The beds and 3 L pots were filled with Plantmax^® substrate and placed in suspended beds. The hydroponic system utilized NFT (Nutrient film technique) and 4 m × 15 cm × 7 cm PVC tubes with a 4% slope and the fertilizers were a commercial formula. Each experiment was 4 treatments in factorial Scheme 2 × 2 with 2 cultivars (Monalisa and Agata) and 2 harvest methods (single and staggered). All three experiments were carried out in randomized design with 6 replicates and 7 plants per replicate.     

Influence of ventilation and sucrose on growth and leaf anatomy of micropropagated potato plantlets

Potato single nodes were cultured in vessels containing MS medium supplemented with 10, 20 and 30 g/l of sucrose. Vessels were closed with a clear polypropylene lid with or without 10 mm microporous polypropylene membrane. Sucrose concentration significantly increased plantlet height, shoot fresh weight and chlorophyll a content. Plantlets grown in ventilated vessels were significantly shorter, had lower shoot fresh weight and higher shoot dry weight than those in non-ventilated vessels. The highest leaf chlorophyll a content (21.83 mg/g fresh weight) was found in plantlets grown in ventilated vessels using MS medium with 20 g/l of sucrose, whereas those grown on medium with 10 g/l of sucrose had the highest chlorophyll b content (24.00 mg/g fresh weight). Total chlorophyll content was significantly higher when plantlets were grown in ventilated vessels containing medium with 10 or 30 g/l sucrose than in non-ventilated vessels. There was no significant difference in total chlorophyll content among plantlets grown in ventilated vessels with different concentrations of sucrose. Stomatal density was significantly lower when plants were grown under ventilated conditions. Leaf replica examination showed that stomata under non-ventilated condition were spherical with wide openings whereas, those in ventilated vessels were elliptical with narrow openings. Plantlets grown in non-ventilated vessels had thinner leaves and failed to build up a distinct defined upper epidermis, palisade parenchyma layer and spongy cells. On the other hand, leaves under ventilated conditions showed comparatively well organized layers with small intercellular space. The vascular system of leaves under the ventilated conditions demonstrated very well developed xylem unlike leaves under non-ventilated conditions. Thus, ventilated vessels with the 20 g/l of sucrose under ambient CO₂ in the growth room could successfully promote photomixotrophic culture and produce healthy plantlets.     

Impact of iron stress on biomass,yield, metabolism and quality of potato (Solanum tuberosum L.)

In order to study the influence of variable iron on biomass, economic yield and role of iron in potato (Solanum tuberosum) cv. Chandramukhi metabolism, plants were grown in refined sand at variable iron ranging from 0.001 to 2.0 mM. Exposure of potato plants to Fe stress (i.e. a Fe concentration different from 0.1 mM) shows retarded growth, decreased chlorophyll concentration and Hill reaction activity, induced changes in enzyme activities and concentration of Fe and Mn. The visible symptoms of iron deficiency appeared on day 15 at 0.001 mM Fe as chlorosis of young leaves. The excess of iron (at >0.1 mM Fe) appeared later, after 25 days and the chlorosis was observed on older leaves. Both deficiency (0.001 mM) and excess (>0.1 mM) of iron reduced the tuber yield, deteriorating its quality by lowering the concentration of sugars, starch and protein nitrogen and increasing the accumulation of non-protein nitrogen and phenols in tubers.     

Chlorocholine chloride application effects on photosynthetic capacity and photoassimilates partitioning in potato (Solanum tuberosum L.)

Treatment of potato (Solanum tuberosum L.) with chlorocholine chloride (CCC) applied twice as a foliar spray 25 and 30 days after planting has shown to decrease shoot and stolon growth but increase tuber yield. However, the regulatory role of CCC on translocation of recently fixed photoassimilates into different parts of potato plants has not been fully illustrated. In this study, ¹⁴C-isotope labelling technique was used to estimate the photosynthetic capacity and photoassimilate partitioning among leaves, stems, roots + stolons, and tubers of potted potatoes treated with 1.5 g l⁻¹ CCC. CCC treatment significantly increased tuber dry mass but reduced leaf dry mass. CCC-treated leaves had significantly higher chlorophyll and carotenoid contents and assimilated 22.0% more ¹⁴CO₂ per leaf dry mass than the controls. Compared with the control, CCC treatment reduced the translocation of ¹⁴C-photoassimilates into leaves, stems and roots + stolons but increased that into tubers. CCC-treated leaves exported 14.6% more ¹⁴C-photoassimilates into other parts of the plants. In addition, CCC treatment reduced ¹⁴C-soluble sugar and ¹⁴C-starch accumulation in leaves and stems but enhanced them in tubers and roots + stolons. Collectively, the results indicate that CCC treatment significantly improves the photosynthetic capacity of potato leaves and promotes photoassimilates partitioning into tubers thereby enhancing tuber growth.     

The effect of size and quality of potato microtubers on quality of seed potatoes in the cultivar ‘Superior’

Potato microtubers produced in vitro of the cultivar ‘Superior’ were assessed to decide up to what size it can be used for the seed potato with respect to storability, dormancy period, and sprouting vigor. The larger microtubers lost moisture content more slowly and retained firmness longer when stored at 4 °C. In the sprouting test, the larger ones had less period of dormancy and showed more vigorous sprouting ability. The starch increased with increasing size of the microtuber and showed the distribution of about 70–80% of dry matter content. The amounts of sugars were positively co-related with the size of the potato. The internal factors such as dry matter and carbohydrate content reveal that potato microtuber follows the field-grown potatoes in all aspects. The results suggest that the size of microtubers can be used as an index for grading their quality as seed potatoes, and the size of the microtuber should be at least 0.5 g to be used as seed potato.     

Foliar application of chlorocholine chloride improves leaf mineral nutrition,antioxidant enzyme activity,and tuber yield of potato (Solanum tuberosum L.)

In southern China, potatoes (Solanum tuberosum L.) are grown in the late season and the crops are often subjected to low temperature stress particularly during the tuber bulking stage. Exogenous chlorocholine chloride (CCC) treatment has been found to improve crop performance under suboptimal growth conditions; however, the physiological mechanisms underlying the beneficial effects have not been fully understood. The objective of this study was to investigate the effects of CCC treatment on mineral nutrition, antioxidant enzyme system, and tuber yield of potato (cv. Zhongshu 3) under field conditions. The plants were foliar sprayed twice with 1.5, 2.0 and 2.5 g l⁻¹ CCC at 24 and 28 days after emergence (DAE), respectively; and plants without CCC treatment were serviced as control. Leaf samples were collected on 56 DAE for determination of mineral nutrition contents and antioxidant enzyme activity. Results showed that 1.5 and 2.0 g l⁻¹ CCC treatments significantly increased the contents of P, K, Ca, Mg, Fe, Mn, Zn and Cu in potato leaves. These treatments also increased superoxide dismutase (SOD), peroxidases (POD) and catalase (CAT) activities in the leaves. A positive linear relationship was found between SOD activity and the content of Fe + Mn + Zn + Cu. Tuber yield was significantly increased by CCC treatment. It is concluded that treatment with certain concentration of CCC (e.g. 1.5–2.0 g l⁻¹) improves mineral nutrition and SOD, POD and CAT activities in potato leaves; which might have contributed to the higher tuber yield of the crop grown under suboptimal conditions.     

Starch granule size variation and relationship with tuber dry matter content in heritage potato varieties

Heritage potato varieties in Canada are historic old varieties collected from Canada and various countries before the formal establishment of the Canadian plant variety registration system and may be a valuable gene resource for beneficial traits in potato breeding and bioproducts development. Greater evaluation is the key for the enhanced use of these materials. It is unknown how much variation of starch granules occurs among Canadian heritage potato varieties. We analyzed the starch granule size of 14 potato heritage varieties held in the Canadian Plant Gene Resources collection over 2 years using a squeezed juice and microscopic method recently developed at the Potato Research Centre. The varieties demonstrated considerable variation in starch granule size and shape. The granules showed average lengths ranging from 18 μm in the variety Congo to 32 μm in ‘Russet Burbank’. The largest single granule measured from 64 μm in ‘Congo’ to 91 μm in ‘Crotte d’Ours.’ The granule sizes of the varieties showed a very high correlation (r = 0.975, P < 0.0001) between years. This high reproducibility suggests the existence of genetic factors in determining starch granule size. We also found that the starch granule size is positively correlated with tuber dry matter (in terms of specific gravity) in these heritage potatoes. The results demonstrated reproducible genotypic variation for starch granule size and shape in tubers with a significant correlation to tuber dry matter in these heritage potato varieties, and offers the possibility for and agronomic relevance of genetic modification of starch granules through selective breeding.     

Capability of the ‘Ball-Berry’ model for predicting stomatal conductance and water use efficiency of potato leaves under different irrigation regimes

The capability of the ‘Ball-Berry’ model (BB-model) in predicting stomatal conductance (g_s) and water use efficiency (WUE) of potato (Solanum tuberosum L.) leaves under different irrigation regimes was tested using data from two independent pot experiments in 2004 and 2007. Data obtained from 2004 was used for model parameterization, where measurements of midday leaf gas exchange of potted potatoes were done during progressive soil drying for 2 weeks at tuber initiation and earlier bulking stages. The measured photosynthetic rate (A_n) was used as an input for the model. To account for the effects of soil water deficits on g_s, a simple equation modifying the slope (m) based on the mean soil water potential (Ψ_s) in the soil columns was incorporated into the original BB-model. Compared with the original BB-model, the modified BB-model showed better predictability for both g_s and WUE of potato leaves on the parameterization data set. The models were then tested using the data from 2007 where plants were subjected to four irrigation regimes: non-irrigation (NI), full irrigation (FI), partial root-zone drying (PRD), and deficit irrigation (DI) for 3 weeks during tuber initiation and earlier bulking stages. The simulation results showed that the modified BB-model better simulated g_s for the NI and DI treatments than the original BB-model, whilst the two models performed equally well for predicting g_s of the FI and PRD treatments. Although both models had poor predictability for WUE (0.47 < r² < 0.71) of potato leaves, the modified BB-model was able to distinguish the effects of the irrigation regimes on WUE being that the WUE was generally greater for PRD than for FI and DI plants. Conclusively, the modified BB-model is capable of predicting g_s and of accounting for the differential effects of irrigation regimes on WUE of potato leaves. This information is valuable for further simulating potato water use thereby optimizing WUE under field conditions.     

Somatic embryo,adventitious root and shoot regeneration in in vitro grown quince leaves as influenced by treatments of different length with growth regulators

The purpose of this work was to acquire more information on the capacity of in vitro grown quince (Cydonia oblonga Mill.) leaves to simultaneously regenerate somatic embryos, adventitious roots and shoots, and to evaluate the variations induced on regeneration response by treatments of different length with growth regulators. After 2 days of liquid treatment with 2,4-dichlorophenoxyacetic acid, the leaves were cultured for 0, 3, 6, 9, 12, 15, 18 and 21 days on gelled growth medium containing the basal components of Murashige and Skoog and kinetin (Kin) 4.5 μM + naphthaleneacetic acid (NAA) 0.5 μM. At the end of each treatment period, the leaves were cultured on a transfer medium in the absence or in the presence of a growth regulator combination represented by N⁶-benzylaminopurine (BA) 2.66 μM + gibberellic acid 0.58 μM + indole-3-butyric acid 0.3 μM. The culture period for all the treatments was fixed to 52 days.     

Use of ISSR,SRAP, and RAPD markers to assess genetic diversity in Turkish melons

The genetic relationships among 63 melon (Cucumis melo L.) genotypes collected from various regions of Turkey were determined by comparing their molecular ISSR, SRAP, and RAPD markers with those of 19 foreign melon genotypes to investigate the taxonomic relationships and genetic variation of Turkish melon germplasm. Total 162 polymorphic markers (69, 18, and 75 obtained from ISSR, SRAP, and RAPD primers, respectively) were used to define the genetic similarity among the melon genotypes by dendrogram or two and three dimensional scalings. The average similarity (SM coefficient) between any two pairs of accessions examined as estimated by molecular variation was 0.73 ± 0.48. Within-group genetic similarities ranged between 0.46 and 0.96. Related genotypes or genotypes collected from similar regions were partitioned to similar clusters. Southeastern Anatolian genotypes were distinctly apart from group inodorus and group cantalupensis (sweet) genotypes. This reinforced the position of Turkey in the secondary genetic diversity center of melon. The genetic diversity among Turkish genotypes (H = 0.28 and I = 0.42) was only a little less than that of the world accessions (H = 0.30 and I = 0.45). On the other hand, the percentage of polymorphic loci among Turkish melon genotypes (90.7%) was even higher than that of the world accessions (87.6%).     

Closed cycle subirrigation with low concentration nutrient solution can be used for soilless tomato production in saline conditions

Closed cycle soilless techniques can be adopted to minimize water and fertilizer losses in greenhouse cultivation. There is a general lack of information regarding the soilless cultivation of vegetables with closed cycle subirrigation techniques, specifically when using saline water. In this study, a trough bench subirrigation system (SUB), with two fertilizer concentrations (“100%”, containing 9.8 mol m⁻³ N-NO₃, 1.6 mol m⁻³ P-H₂PO₄, 8.7 mol m⁻³ K⁺, 2.8 mol m⁻³ Ca⁺, 1.8 mol m⁻³ Mg⁺, 4 mol m⁻³ S-SO₄, and “70%”, containing 70% of the macronutrient concentration) in the nutrient solution (NS), was compared with open cycle drip-irrigation (DRIP with “100%” NS). For all the three treatments, NS was prepared using rain water (0.05 dS m⁻¹) and adding NaCl (1 g L⁻¹), in order to simulate moderate saline irrigation water. The effect of the treatments on tomato (Solanum lycopersicum L.) plant growth, yield, fruit quality, water use efficiency (WUE) and fertilizer consumption was evaluated. Substrate and recirculating NS composition were also studied. Subirrigation, regardless of NS concentration, reduced plant height (by 30 cm), leaf area (by 1411 cm²), total fresh and dry weight (by 429 and 48.5 g plant⁻¹, respectively) but not dry matter percentage of the whole plant, with respect to DRIP. Yield was reduced when plants were subirrigated with the higher concentrated NS, but no differences with open cycle DRIP were recorded when the lower NS concentration was used in SUB. Fruit quality was not affected by irrigation system or NS concentration. The higher WUE was obtained with subirrigation. NaCl accumulated similarly over the crop cycle in recirculating NS of both SUB treatments and in growing substrates of all the three treatments. Higher salt concentration was found in subirrigated substrates, in particular in the upper part of the substrate profile. Fertilizers accumulated in the subirrigated substrates when the higher NS concentration was used, but not when the NS concentration was reduced by 30%. The results of this study indicate that tomato can be grown successfully in a closed cycle subirrigation system, using saline water, by reducing the fertilizer NS concentration normally used with traditional open cycle systems.     

Effect of hydrogen cyanamide,mineral oil and thidiazuron in combination with tip pruning on bud break,shoot growth and yield in ‘Bourjasotte Noire’, ‘Col de Damme Noire’ and ‘Noire de Caromb’ figs

Commercial fig production is relatively new to the Mediterranean-type climate Western Cape Province of South Africa. A lack of lateral branch development impedes tree structure development and therefore adequate yields of quality fruit. The chemical rest breaking agents, Lift^® (thidiazuron 3 g L⁻¹) at 6%, Dormex^® (hydrogen cyanamide, 520 g L⁻¹) at 4%, mineral oil at 4% and a combination of mineral oil and Dormex^® at 2% each were evaluated in a split plot design in combination with tip-pruning vs. no-pruning to overcome apical dominance and increase complexity (Experiment 1). During the 2008/2009 season, an additional investigation was conducted to evaluate the use of thidiazuron and hydrogen cyanamide for harvest scheduling (Experiment 2). Dormex^® at 3% and Lift^® at 6%, were applied to dormant trees on 30 June 2008, 3 August 2008, 15 August 2008 or 30 August 2008. In general, Lift^® can be used to increase the number of buds breaking in ‘Bourjasotte Noire’ and ‘Col de Damme Noire’, while tip pruning decreased bud break with a resultant increase in shoot length. Dormex^® and oil combined decreased bud break in these two cultivars but was effective on ‘Noire de Caromb’. Where bud break was increased the resultant N + 1 shoot length was decreased. RBAs increased the number of fruit in both the breba and main crop of ‘Noire de Caromb’, but decreased fruit size of the breba crop. Our data are not conclusive as to what the reason for low lateral bud break might be but leans towards strong AD in seasons with 400 Utah CU or more, but might include some delayed foliation response in seasons with less than 200 Utah CH.     

The impact of sodium chloride on root growth,cell division,and interphase silver-stained nucleolar organizer regions (AgNORs) in root tip cells of Allium cepa L.

To evaluate genetic damage, parameters including root growth, chromosomal aberrations, and interphase silver-stained nucleolar organizer regions (AgNORs) in root tip cells of Allium cepa L. were investigated after treatment with NaCl (40–160 mM). The results showed that NaCl caused a decrease in root growth. All concentrations of NaCl showed an inhibitory effect on dividing cells in root tips of A. cepa L. and caused a reduction in mitotic index values. Upon exposure to NaCl, roots exhibited various mitotic abnormalities, including c-mitosis, anaphase bridge, and chromosome stickiness. In addition, interphase cells with micronuclei, budding nuclei, and unequal-sized nuclei were observed. Moreover, total cell aberration increased with increasing NaCl concentration. For AgNOR parameters, the average number of AgNORs per nucleus decreased in roots treated at all NaCl concentrations. The singular AgNOR area and whole AgNOR area in the nucleus containing 1–3 AgNORs were inversely proportional to NaCl concentrations.     

Comparison of SSR polymorphisms using automated capillary sequencers,and polyacrylamide and agarose gel electrophoresis: Implications for the assessment of genetic diversity and relatedness in almond

In this work we have performed a comparative study of the utilization of three electrophoresis separation methods for the analysis of peach SSR polymorphism in almond and its implications in the assessment of genetic diversity and relatedness. Automated SSR detection and polyacrylamide gel electrophoresis were the most efficient methods and would be able to resolve allelic variation at a finer scale than the electrophoresis in MetaPhor^® agarose. Moreover, automated electrophoresis detection is much more expensive in terms of cost of equipment and cost of the analysis. In addition, SSR detection using polyacrylamide gel electrophoresis showed similar results than automated sequencing, although it is more time-consuming and toxic than electrophoresis in agarose gels. Discrepancies among polyacrylamide and automated capillary, and MetaPhor^® were observed when differences in SSR polymorphisms were between 1 and 5 bp. While the use of MetaPhor^® agarose appears less indicated for genotype characterization, this technique may be the most convenient in other applications, i.e. mapping of population, due to its lower cost and easier routine application. The utilization MetaPhor^® agarose produced a slightly different clustering of genotypes in spite of the big differences observed in the DNA fingerprinting. However, bootstrap values using MetaPhor^® agarose were lower indicating a lower accuracy of this SSR polymorphism analysis method.     

Diurnal variations in gas exchange,chlorophyll fluorescence quenching and light allocation in soybean leaves: The cause for midday depression in CO2 assimilation

Gas exchange and chlorophyll fluorescence quenching analysis were carried out to investigate the diurnal variations in photosynthesis and light allocation in leaves of soybean. Leaf net CO₂ assimilation rate showed a bimodal diurnal pattern and midday depression of CO₂ assimilation was observed at 13:00 h. Depression in CO₂ assimilation at midday was mostly attributed to non-stomatal limitation since the reduction in net CO₂ assimilation rate was not followed by significant reductions in stomatal conductance and intracellular CO₂ concentration. Midday depression in CO₂ assimilation was found to be associated with reversible inactivation of photosystem II reaction centers and increases of antenna heat dissipation and photorespiration in response to the high light intensity. It is likely that PS II down-regulation, heat dissipation and photorespiration co-operated together to prevent the chloroplast from photodamage.     

Water relations between leaf water potential,photosynthesis and agronomic vine response as a tool for establishing thresholds in irrigation scheduling

During the last few years, leaf water potential has been a useful tool in controlling vine water status. However, the time of measurement that could best explain short- and long-term vine responses remains a matter of discussion. The objectives of this work were to study the relationship between vine water status and vine performance and to determine what time of day leaf water potential is best correlated to physiological performance and agronomic vine response. The assay was conducted in Madrid, Spain. Plant material was Cabernet-Sauvignon (Vitis vinifera L.) grafted onto SO₄. Three irrigation treatments were established: T1 was non-irrigated, and T2 and T3 were irrigated with a constant fraction of the ETo, k = 0.45 and 0.2, respectively. Vine water status was monitored through predawn, midmorning and noon leaf water potential. Their relationships with net CO₂ assimilation rate, vegetative growth rate, yield components and must composition at harvest were studied for 3 consecutive years. Shoot growth rate and net CO₂ assimilation rate were better correlated with midmorning and noon leaf water potentials – Ψ_m and Ψ_n – than predawn leaf water potential – Ψ_pd – but all of them were significant. Shoot growth rate was zero for Ψ_pd = −0.48, Ψ_m = −1.12 and Ψ_n = −1.18 MPa. Berry size was better correlated with the water stress integral for predawn (S_Ψpd$S_{{\Psi }_{\text{pd}}}$) although the water stress integral for midmorning (S_Ψm$S_{{\Psi }_{\text{m}}}$) and noon (S_Ψn$S_{{\Psi }_{\text{n}}}$) performed quite well. No relationship was found between the water stress integral and TSS, total acidity or pH. Leaf water potential performed as a good parameter for determining both vine water status and agronomic response, but not for evaluating must composition.