Non-destructive leaf area estimation in chestnut

In this research, an equation for estimating the leaf area was derived for the chestnut tree by using 18 chestnut genotypes and by measuring the lamina width, length and leaf area without damage being caused in 2004–2005. Multiple regression analysis for the genotypes was separately performed. The proposed leaf area (LA) estimation model is: LA = 3.36 + 0.11L² − 0.26L²/W² + 1.1W², R² = 0.988, where LA is the leaf area, W is the leaf width and L is the leaf length. The model was validated by measuring leaf samples of the SE-21-2 genotype in different climate conditions in 2004–2005.     

A simple model for estimating leaf area of hazelnut from linear measurements

Simple, accurate and non-destructive models determining leaf area of plants are important for many experimental comparisons. Determining the individual leaf area (LA) of hazelnut (Corylus avellana L.) involves measurements of leaf parameters, such as length (L) and width (W), or some combinations of these parameters. Two-year investigation was carried out during 2005 (on 20 genotypes) and 2006 (on one cultivar) under open field conditions, respectively, to test whether a model could be developed to estimate leaf area across genotypes and environments. Regression analyses of LA versus L and W revealed several models that could be used for estimating the area of individual hazelnut leaves. A linear model having LW as the independent variable (LA = 2.59 + 0.74LW) provided the most accurate estimate (R² = 0.982, MSE = 29) of hazelnut LA. Validation of the model having LW of leaves measured in the 2006 experiment coming from other genotype grown under different environmental conditions showed that the correlation between calculated and measured areas was very high.     

Calibration and validation of regression model for non-destructive leaf area estimation of saffron (Crocus sativus L.)

Leaf area measurements are required in several agronomical and physiological studies. Usually, there is an interest for measurement methods that are simple, quick and that will not destroy the leaf. The objectives of this study were to establish equations to estimate leaf area (LA) by using length (L), width (W) and dry weight (DW) of saffron leaves. Leaves of different sizes were collected from the experimental area at different time intervals. Leaf area was measured with an automatic measuring device and leaf dimensions were determined with a ruler. An equation for estimating the leaf area from L and W was developed and validated with the area of leaves collected during different periods. Regression analyses of LA versus L, W, LW and DW led several models that could be used for estimating the area of individual saffron leaves. A exponential model having L as the independent variables [LA = 191.33e^(L)0.0037] provided the most accurate estimate (R² = 0.9373, RMSE = 27.68) of saffron leaf area. Validation of the regression model showed that the correlation between measured and simulated values by the use of this equation was very high.     

Non-destructive leaf area estimation model for faba bean (Vicia faba L.)

In this study, a leaf area estimation model was developed for faba bean (Vicia faba L.) using the linear measurements such as lamina length (L) and width (W) by stepwise regression analysis. Leaflets from fourteen faba bean genotypes, including three cultivars (Eresen-87, Filiz-99 and Lara), two lines (FLIP85-172FB and FLIP86-116FB) and nine local genotypes, were used to develop the model in 2003-2004. The proposed leaf area (LA) estimation model is LA = 0.919 + 0.682LW, R² = 0.977. In 2004–2005 growing season, this model was validated by measuring new leaf samples from the different level of the plant canopy (lower, middle and upper) of faba bean cvs. Eresen-87 and Filiz-99 sown in both autumn and late winter. Produced model in this study can be reliably used for estimating area of leaf samples from the different level of the plant canopy of faba bean cvs. Eresen-87 and Filiz-99 sown in both autumn and late winter.     

Estimation of individual leaf area,fresh weight,and dry weight of hydroponically grown cucumbers (Cucumis sativus L.) using leaf length,width, and SPAD value

Non-destructive and mathematical approaches of modeling can be very convenient and useful for plant growth estimation. To predict individual leaf area, fresh weight, and dry weight of a cucumber (Cucumis sativus L.), models were developed using leaf length, leaf width, SPAD value, and different combinations of these variables. Eight regression equations, commonly used for developing growth models, were compared for accuracy and adaptability. The three nonlinear models developed were as follows: individual leaf area (LA) = −210.61 + 13.358W + 0.5356LW (R² = 0.980^***), fresh weight (FW) = −2.72 + 0.0135LW + 0.00022LWS (R² = 0.956^***), and dry weight (DW) = 0.25 − 0.00102LS + 0.000077LWS (R² = 0.956^***), where L is the leaf length, W the leaf width, S the SPAD value, and LWS = L × W × S. For validation of the model, estimated values for individual leaf area, fresh weight, and dry weight showed strong agreement with the measured values, respectively. Leaf dry weight, especially, was estimated with a higher degree of accuracy through the use of a SPAD value, as well as leaf length and width. Therefore, it is concluded that models presented herein may be useful for the estimation of the individual leaf area, fresh weight, and dry weight of a cucumber with a high degree of accuracy.     

Estimating leaf area of plantain

The area of leaves of plantain (Musa acuminata × Musa balbisiana) was traced on graph paper. Then the length (L) and the maximum width (W) were measured. A known leaf area from each leaf was taken and both the sample and the remaining leaf blades were dried and weighed. Using known leaf area and their dry weights, the leaf area of each whole leaf was determined. From the regression equation, a coefficient for estimating the true leaf area from the L × W measurements was determined to be 0.8 (approx.) which was statistically significant (P = 0.05).Using a mathematical method (independent of the first method), the coefficient for estimating the true leaf area of plantain was found to be 0.7854. A significant correlation (r, 0.001 = 0.73) was also found between the area traced on graph paper and that determined using the coefficient 0.8 (L × W).     

Establishment of in vitro tissue cultures from Echinacea angustifolia D.C. adult plants for the production of phytochemical compounds

The establishment of in vitro cultures of Echinacea angustifolia D.C. was obtained directly from sections of flower stalks of adult plants. The shoot formation was obtained from this plant material placed on a modified MS basal medium named CH supplemented with 0.5 mg L⁻¹ 6-benzylaminopurine (BA). The in vitro propagation procedure of E. angustifolia consisted of three distinct phases: an initial regeneration phase from stalk sections (IP shoots on basal medium with 0.25 mg L⁻¹ BA), an elongation phase on active charcoal and an axillary proliferation of the shoots (AP shoots on basal medium with 0.5 mg L⁻¹ BA).Regenerating calli were established from leaves of in vitro shoots cultured on CH medium supplemented with 3 mg L⁻¹ BA and 0.5 mg L⁻¹ indole-3-butyric acid (IBA). Developed shoots from the callus cultures were subcultured on the CH medium with 0.5 mg L⁻¹ BA (leaf regenerated shoots: LR shoots). The secondary metabolite content of the in vitro plant material was compared with that of the greenhouse growing plants. The quali-quantitative LC-DAD-ESI-MS analysis on the extracts from axillary proliferation shoots (AP shoots) showed significant production of caffeic acid derivatives while leaf callus and LR shoots, accumulated mainly alkamides. These results showed that the proper choice of the procedures for in vitro multiplication allowed us to obtain plant biomass able to produce the active compounds typical of E. angustifolia plants.     

Mapping leaf area of urban greenery using aerial LiDAR and ground-based measurements in Gothenburg,Sweden

Leaf area of urban vegetation is an important ecological characteristic, influencing urban climate through shading and transpiration cooling and air quality through air pollutant deposition. Accurate estimates of leaf area over large areas are fundamental to model such processes. The aim of this study was to explore if an aerial LiDAR dataset acquired to create a high resolution digital terrain model could be used to map effective leaf area index (L_e) and to assess the L_e variation in a high latitude urban area, here represented by the city of Gothenburg, Sweden. L_e was estimated from LiDAR data using a Beer-Lambert law based approach and compared to ground-based measurements with hemispherical photography and the Plant Canopy Analyser LAI-2200. Even though the LiDAR dataset was not optimized for L_e mapping, the comparison with hemispherical photography showed good agreement (r² = 0.72, RMSE = 0.97) for urban parks and woodlands. Leaf area density of single trees, estimated from LiDAR and LAI-2200, did not show as good agreement (r² = 0.53, RMSE = 0.49). L_e in 10 m resolution covering most of Gothenburg municipality ranged from 0 to 14 (0.3% of the values >7) with an average L_e of 3.5 in deciduous forests and 1.2 in urban built-up areas. When L_e was averaged over larger scales there was a high correlation with canopy cover (r² = 0.97 in 1 × 1 km² scale) implying that at this scale L_e is rather homogenous. However, when L_e was averaged only over the vegetated parts, differences in L_e became clear. Detailed study of L_e in seven urban green areas with different amount and type of greenery showed a large variation in L_e, ranging from average L_e of 0.9 in a residential area to 4.1 in an urban woodland. The use of LiDAR data has the potential to considerably increase information of forest structure in the urban environment.     

Water status,leaf area and fruit load influence on berry weight and sugar accumulation of cv. ‘Tempranillo’ under semiarid conditions

Berry weight (BW) and sugar concentration (SC) are relevant indices in viticulture since they can be easily measured and, when considered together, give a relatively fair estimation of grape quality. This work aims to evaluate the influence of water availability, leaf area and fruit load on BW and SC, estimating the relative importance of these factors. Leaf area (LA), berry number (BN), yield (YLD), water potential in summer (ψ_pd-s), BW and SC were measured in 16 and 17 ‘Tempranillo’ vineyards in 1999 and 2000, respectively. In all the vineyards, according to local practices, the irrigation amount decreased as summer progressed. The study vineyards comprised a broad range of situations concerning leaf area, fruit load and water status in summer. Average leaf water potential in summer and LA/BN ratio, when considered together, estimated properly BW (R² = 0.91; P < 0.001) and, in a similar way, ψ_pd-s and LA/YLD ratio estimated SC (R² = 0.74; P < 0.001). The relative weight of ψ_pd-s in both relationships was much higher than that of any of the LA:fruit ratios, showing that, under semiarid conditions, water availability plays the main role in regulation of berry growth and sugar accumulation and, therefore, the highest attention should be paid in these areas to irrigation management, seeking the degree of stress that allows optimizing the combination of yield and berry quality in each situation.     

Development of a disease severity rating scale for plane tree anthracnose

Anthracnose caused by the fungus Apiognomonia veneta (Sacc. et Speg.) Höhnel., is the most important and frequent disease affecting mature ornamental plane trees (Platanus×hybrida Brot.=P.×acerifolia (Ait.)Willd.) of central Spain. Symptoms of the disease are: leaf vein and petiole necrosis, bud death, defoliation, proliferation of shoots growing in whorls, short internodes, cankers, necrotic lesions and twigs and branches growing in angles. Based on our previous experience, a disease severity rating scale (DSRS) has been established, consisting of six levels: 0=healthy, 1=initial, 2=low, 3=medium, 4=high and 5=dead. In order to achieve a better and more efficient measure of disease intensity we tried to quantify this visual scale using mathematical criteria. In 2000, 610 mature trees up to 200 years old, divided into 4 age classes, were selected and systematically evaluated using a visual estimation based method. The trees were located in central Spain, mainly in two periurban areas of the town of Aranjuez (south of Madrid) and in three urban areas of Madrid city. Trees were observed in late spring, summer and winter. We recorded visual estimation of disease severity, foliage cover, healthy new shoots, dead branches, shoot growth in whorls and branch growth in angles. The statistical relationship between the parameters, disease severity and all the variables recorded (defoliation, healthy new shoots, etc.) has been evaluated. “Leaf density”, “dead branches” and “healthy shoots” were the variables that help to discriminate better between the different levels of the DSRS. A clearer definition of the different phases of disease severity will facilitate the application of possible control methods and the prediction of the behaviour of other Platanus spp.     

Methyl jasmonate plays a role in fruit ripening of ‘Pajaro’ strawberry through stimulation of ethylene biosynthesis

The role of methyl jasmonate (MJ) in strawberry (Fragaria × ananassa Duch. cv Pajaro) fruit ripening was investigated by monitoring its endogenous concentrations in fruit at various stages of development and the effects of exogenously applied MJ at these stages on ethylene biosynthesis. The concentration of endogenous trans-MJ was significantly higher in the white fruit (31.7–162.2 ng g⁻¹) and decreased sharply in half and fully ripe fruit. Higher concentrations of endogenous trans-MJ at the white stage of strawberry fruit development followed by a decline during fruit ripening indicate that MJ may play an important role in modulating fruit ripening. Significantly increased ethylene production was measured in the fruit when MJ was applied at white, half ripe and at fully ripe stage. The application of MJ (50 μM) resulted in significantly highest ethylene production and increased activities of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase as compared to all other treatments. The effect of exogenously applied MJ on ethylene production, ACC synthase and ACC oxidase activities was dependent on concentration of MJ applied and on fruit developmental stage. In conclusion, MJ in strawberry modulates fruit ripening, as its concentration is higher in white fruit and is declined with the progression of ripening and exogenous application of MJ increases ethylene production, activities of ACC oxidase and ACC synthase depending upon the concentration of MJ applied and fruit developmental stage.     

Effects of nutrient solution electrical conductivity and sulfur, magnesium, and phosphorus concentration on sesquiterpene lactones in hydroponically grown lettuce (Lactuca sativa L.)

The effect of nutrient solution electrical conductivity (EC) and sulfur (S), magnesium (Mg), and phosphorus (P) levels on the content of the primary sesquiterpene lactones (SLs), lactucin, 8-deoxylactucin, and lactucopicrin, in hydroponically grown lettuce was assessed. Lettuce grown at 4 EC levels (0.5, 1.0, 2.0, and 3.0 dS m⁻¹) displayed significant differences in leaf area index, number of leaves, plant height, fresh weight per plant, and chlorophyll content that were highest at EC 2.0 dS m⁻¹. Lactucin (5.5 μg g⁻¹ dry weight), 8-deoxylactucin (7.5), lactucopicrin (35.8), and total SLs (48.7) concentraions were highest at EC 0.5 dS m⁻¹. Four S (8, 16, 48, and 80 mg L⁻¹) and Mg (6, 12, 36, and 60 mg L⁻¹) levels and 3 P (8, 16, and 48 mg L⁻¹) levels were assessed for their effect on individual and total SLs. S and P had the greatest effect on SL levels. Plants in the lowest S level had significantly higher lactucin, lactucopicrin and total SLs. Each of the SLs was higher in the highest P level while Mg influenced only the lactucopicrin level in a quadratic manner. The results indicate that solution culture conditions can strongly influence the SL concentration and therefore bitterness and acceptability of lettuce.     

Cross-pollination improves ‘Orri’ mandarin fruit yield

‘Orri’, a selection of ‘Orha’ mandarin [Temple (Citrus temple hort. ex Y. Tanaka) × Dancy (Citrus tangerina hort. ex Tanaka)], is a new high-quality Israeli mandarin which, in the last decade, has become one of the leading varieties in Israel. ‘Orri’ has an excellent taste, the rind is deep orange in color and easily removed, and it contains few or no seeds. However, ‘Orri’ grown in Israel suffers from inadequate yield and no published studies have yet addressed this problem. In the present study we determined that ‘Orri’ productivity depended on conditions being favorable to cross-pollination. Under cross-pollination conditions a positive correlation (R² = 0.97) was found between yield per tree and number of fruits per tree, and more than 90% of the fruits exceeded 60 mm: the most profitable size range. These data suggest that the number of fruits per tree, and not fruit size, is the limiting factor for yield improvement in ‘Orri’ orchards. Studying seed set showed that ‘Michal’ mandarin (Citrus reticulata Blanco) is a compatible pollenizer for ‘Orri’ flowers: the number of seeds per ‘Orri’ fruit increased as the distance from ‘Michal’ trees decreased. The present study demonstrated that cross-pollination of ‘Orri’ resulted in yield improvement, yet at the price of increased seed set.     

Characterization of tetraploid plants regenerated via protoplast culture of Iris fulva and their crossability with Japanese irises

Characteristics such as flower form, size and color of outer and inner perianths, anthocyanins in outer perianths, size, color and fertility of pollen and self-fertility of diploid and tetraploid lines regenerated via protoplast culture of Iris fulva were examined and compared with those of the diploid wild line. Among these characteristics, flower form, inner and outer perianth sizes of the tetraploid lines were noticeable, because these lines had upward flower forms and bigger flowers than diploid lines. Furthermore, reciprocal crosses between diploid or tetraploid lines of I. fulva and I. ensata and those of I. fulva and I. laevigata were performed. Three seedlings were obtained from the cross of tetraploid I. fulva × diploid I. laevigata through embryo rescue. One of them was identified as the interspecific hybrid between tetraploid I. fulva and I. laevigata by flow cytometoric (FCM), cytological and molecular (RAPD) analyses. This is the first report on production of hybrids from these lines. I. fulva has unique brown flowers, and this trait could be very useful for flower color breeding of I. laevigata which lacks this color. Therefore, the hybrid of I. fulva (4×) × I. laevigata may be the best available gene source for brown color breeding of this species.     

Use of a cyclic high-pressure sodium lamp to inhibit flowering of chrysanthemum and velvet sage

Photoperiod is commonly controlled in the commercial production of ornamental crops to induce or prevent flowering. Flower induction in short-day (SD) plants can be prevented or delayed when the natural daylength is short by providing low-intensity lighting during the dark period. A stationary high-pressure sodium (HPS) lamp with an oscillating aluminum parabolic reflector (cyclic HPS) has been developed to provide intermittent lighting to greenhouse crops. We determined the efficacy of a cyclic HPS lamp at preventing flowering in SD plants garden chrysanthemum [Chrysanthemum × grandiflorum (Ramat.) Kitam.] ‘Bianca’, pot chrysanthemum ‘Auburn’, and velvet sage (Salvia leucantha L.) relative to traditional night interruption (NI) lighting strategies. Plants were grown in a glass-glazed greenhouse at a mean daily temperature of 19.5–20.7 °C with natural SD photoperiods. NI lighting was delivered during the middle of the night (2230–0230 h) from a 600 W cyclic HPS lamp mounted at one gable end of the greenhouse or from incandescent (INC) lamps that were illuminated for the entire 4 h (CONT INC) or for 6 min every 30 min for 4 h. Plants under cyclic HPS were grown at lateral distances of 1, 4, 7, 10, or 13 m from under the lamp. Control plants were grown under an uninterrupted 15 h skotoperiod. As the distance from the cyclic HPS lamp increased from 1 to 13 m, the maximum irradiance measured during the NI decreased from 25.4 to 0.3 μmol m⁻² s⁻¹ and time to visible inflorescence (VI) and the number of nodes at VI decreased. All species had a VI within 54 d, but ≤10% of plants flowered when grown at a lateral distance of 1 or 4 m from the cyclic HPS lamp or under CONT INC. Plants grown without NI had a VI 2 to 15 d earlier and flowered 7 to 24 d earlier than plants grown at 10 or 13 m from the cyclic HPS. All garden chrysanthemums flowered under cyclic INC, whereas velvet sage and pot chrysanthemum had 15% and 35% flowering, respectively. These results indicate that a cyclic HPS lamp can be used effectively to delay flower induction and prevent flowering in these species when NI is delivered at ≥2.4 μmol m⁻² s⁻¹.     

Phosphorus toxicity in the Proteaceae: A problem in post-agricultural lands

South African Proteaceae are adapted to the low soil phosphorus (P) concentrations of the Cape Floristic Region. The efficient P uptake by Proteaceae means that these plants experience phosphorus (P) toxicity at lower rhizosphere [P] than crop plants. This is only problematic when cultivating Proteaceae (and many plants from this region) on previously agricultural land with high residual soil [P]. In this study we hypothesize that P toxicity will result in element imbalances in leaves of Proteaceae and information from this study aims to facilitate ameliorative treatments. Phosphorus toxicity was induced on-farm in Leucadendron ‘Safari Sunset’ (Proteaceae) with subsequent mapping of element distribution in non-necrotic leaf tissue using micro particle-induced X-ray emission spectrometry. Phosphate supply up to 0.01 mM in a fertigation solution resulted in increased stem length of Leucadendron ‘Safari Sunset’ while P concentrations in excess of this resulted in decreased stem length, increased leaf [P] up to 0.25% (w/w) and, between 1 mM and 5 mM P supply, typical P toxicity symptoms were observed. High P supply (5 mM P) resulted in increased leaf [P] in most leaf tissues including the epidermis, where calculations from an equilibrium speciation model indicated that there was 30% more dissolved PO₄³⁻ in the epidermis compared to leaves at low P supply (0 mM added P on soil with 34 mg P kg⁻¹). Concomitantly, bundle sheath and epidermal [Ca] were reduced and 10% more Ca was predicted to be adsorbed and precipitated as hydrapatite at high P supply. High P supply resulted in increased leaf [Cl] and [Mn] in all tissues studied; decreased total leaf [Fe], bundle sheath, xylem, phloem and epidermal [Fe] and decreased total leaf [Zn] and xylem and phloem [Zn]. The observed symptoms of P toxicity in Leucadendron ‘Safari Sunset’ (necrosis in some plants, chlorosis and leaf rosetting) co-occurred with (1) excess PO₄³⁻, which may bind Ca in the epidermis (leading eventually to necrosis); (2) reduced [Fe] and increased [Mn] (leading to chlorosis) and (3) reduced total and vascular [Zn] (leading to leaf rosetting).     

Effect of foliar applied phosphatic fertilizer on absorption pathways, yield and quality of sweet persimmon

Pot and field experiments were conducted to identify nutrient absorption pathways, growth, yield and quality of sweet persimmon using ³²P tagged fermented mono-calcium di-hydrogen phosphate (FMCP) and normal FMCP fertilizer, respectively. In pot experiment, lower surface treated leaf absorbed higher amount of radionuclide phosphorus than upper surface treated leaf and phosphorus absorption increased with the increase in duration. The highest radioactive phosphorus absorption obtained was 8.88 × 10⁴ and 3.57 × 10⁴ Bq/g dry weight of leaf against dorsal and ventral treated leaf surfaces at 96 h after fertilizer application. During experimentation, stomata were closed from 2 to 10 h after application of FMCP fertilizer and nutrient absorption was higher in the lower surface than the upper surface. As a result, phosphorus was absorbed through cuticle by diffusing in aqueous pores in lower surface of leaf. Alternate day and night (24–96 h), lower surface also performed higher amount of phosphorus absorption than upper surface of leaf due to stomatal activity and aqueous pores because lower surface contains higher number of stomata than upper surface of sweet persimmon. It may be concluded that aqueous pores as well as stomata can be important pathways for the absorption of foliar applied FMCP fertilizer. In field experiment, foliar application of normal FMCP fertilizer increased the vegetative growth, number of effective flowering buds and decreased insect–disease infestation of sweet persimmon over control. Sweet persimmon yield increased due to the fact of decreasing trend of fruit dropping by foliar fertilization. Maximum fruit number (1110 and 1449 per tree) was observed in T₄ (foliar spray @ 7.5 ppm P of FMCP fertilizer) and T₅ (alternate foliar spray of 10 and 7.5 ppm P of FMCP fertilizer) treatments in 2005 and 2006, respectively. In T₄ and T₅ treatments, the average fruit yield increased by 153.0 and 211.4 kg tree⁻¹ in 2005 and 2006 over control, respectively. FMCP fertilizer gave maximum fruit yield in T₄ and T₅ treatments in 2005 and 2006, respectively and it differed from other foliar treatments including control. Treatment T₅ increased fruit hardness (2.32 kg/Ø 5 mm), ⁰brix content (14.0%) and reduced acidity (0.018%) in 2005. These results allow us to infer that foliar application of FMCP fertilizer was not only augmenting the fruit yield of sweet persimmon but also improved the quality of produce.     

PLBs induction and clonal plantlet regeneration from leaf segment of commercial hybrids of Phalaenopsis

Induction of Protocorm-like bodies (PLBs) from leaf segments is a clonally propagation technology that used somatic embryogenesis regeneration from in vitro buds of floral stalks, and is a potential alternative for replacement actual low-yield and high-cost clonal propagation of Phalaenopsis orchids. The objective of this work was to evaluate induction of PLBs in leaf segments of two commercial hybrids of Phalaenopsis, arranged in culture media with different combinations of plant growth regulators. The leaf segments (0.4–0.5 cm²) used for PLBs inductions were obtained from young in vitro-induced shoots from inflorescence stalks. They are cultivated in NDM culture media, supplemented with combinations of plant growth regulators Naphthaleneacetic Acid, Thidiazuron and Benzyladenine. The flasks were kept for 60-d in darkness and then for cold white light with photon flux density of 35–40 μmol m^?2 s^?1. The cultivar ‘Ph908’ showed a higher percentage of leaf segments with PLBs (45%) and number of PLBs (25 per leaf segment), in medium containing 0.25 mg L^?1 of TDZ, whereas ‘RP3’ showed only 10% containing PLBs and 2 PLBs per leaf segment in NDM with 1.0 mg L^?1 NAA, 20 mg L^?1 BA and 0.125 mg L^?1 TDZ.     

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.     

Water-use efficiency and evapotranspiration of mango orchard grown in northeastern region of Brazil

Knowledge of evapotranspiration (ET) and water-use efficiency (WUE) is essential in crops management mainly in arid and semiarid regions where water resources are scarce for irrigation. Field experiments were conducted at a commercial farm to obtain the WUE and ET of mango orchard growth in a semiarid environment of northeastern region of Brazil. Measurements were performed within a randomly selected experimental plot with the spacing of 10 m × 5 m between rows and plants. Soil water balance method was used to obtain the mango orchard evapotranspiration while the Penman–Monteith method (FAO/56) was used for determination reference evapotranspiration (ET_o). Soil water content was determined by six tensiometer sets installed at 0.20 m layer intervals from the soil surface down to 1.20 m soil depth. The experimental plot was irrigated with a sprinkler irrigation system based on four irrigation levels (T1 = 70%, T2 = 80%, T3 = 90% and T4 = 100% of ET_o. Results showed that ET and WUE are strongly influenced by soil water availability. Mango yield varied from a minimum value of 28.06 ton/ha in treatment T4 to a maximum value of 31.06 ton/ha in treatment T3. Such difference was found to be statistically significant (P < 0.05) by Tukey's test. Results also indicated that WUE values based on irrigation and evapotranspiration were maximum and minimum for low (treatment T1) and high (treatment T4) water levels, respectively.