Leaf Macro Research Articles

The effectiveness of grafting to improve alkalinity tolerance in watermelon

The aim of the present study was to determine whether grafting could improve alkalinity tolerance of watermelon, and to study the changes induced by the rootstock in the shoot growth at agronomical, physiological, and biochemical levels. Two greenhouse experiments were carried out to determine growth, net photosynthetic rate, electrolyte leakage, root Fe(III)-chelate reductase (FCR) activity, mineral composition and assimilate partitioning (experiment 1, 2007), and organic acid concentration in root exudates (experiment 2, 2008), of watermelon plants [ Citrullus lanatus (Thumb.) Matsum. and Nakai cv. ‘Ingrid’] either ungrafted or grafted onto the four commercial rootstocks: ‘Macis’, ‘Argentario’[ Lagenaria siceraria (Mol.) Standl.] and ‘P360’, ‘PS1313’ ( Cucurbita maxima Duchesne × Cucurbita moschata Duchesne) grown in a closed-loop system. Plants were supplied with nutrient solutions having two levels of pH (6.0 or 8.1). The high pH nutrient solution had the same basic composition plus an additional of 10 mM NaHCO 3 and 0.5 g L −1 CaCO 3. Significant depression of shoot, root biomass production, and leaf macro- (N, P, K, and Mg) and microelements (Fe, Mn, Zn, and Cu) under high pH level was observed in both grafted and ungrafted plants. Increasing the concentration of NaHCO 3 from 0 to 10 mM in the nutrient solution significantly enhanced FCR activity of root tips to 2.3 times in high pH treatment in comparison to the control. At high pH level, the percentage of shoot biomass weight reduction was significantly lower in plants grafted onto pumpkins rootstocks in comparison to those grafted onto the bottle gourd rootstocks and the ungrafted plants. Moreover, at high pH level, the highest percentage of root biomass weight reduction was recorded in both grafting combinations ‘Ingrid/P360’ and ‘Ingrid/Macis’. The high pH-related reduction in net assimilation was more severe in ungrafted plants in comparison with the grafted ones. The Fe concentration in leaves was significantly higher in plants grafted onto pumpkin rootstocks (avg. 109.5 μg g −1) in comparison to that of bottle gourd rootstocks and ungrafted plants (avg. 86.7 μg g −1). For plants grafted onto bottle gourd rootstocks and ungrafted plants the high pH level (8.1) in the nutrient solution caused significant decrease in macronutrient leaf concentration especially for P and Mg compared to plants grafted onto pumpkin rootstocks. Increasing the nutrient solution pH from 6.0 to 8.1 increased exudation of organic acids (citric, malic, tartaric and succinic acids). Watermelon plants grafted onto pumpkin rootstocks exuded more citric and malic acids than those grafted onto bottle gourd rootstocks and ungrafted plants especially under bicarbonate-enriched conditions. These results support the hypothesis that uptake of nutrients (e.g. P, Mg, and Fe) from the nutrient solution by pumpkin rootstocks was facilitated by exudation of organic acids from roots.

DRIS Use on Apple Orchard Nutritional Evaluation in Response to Potassium Fertilization

The aim of this work was to use the diagnosis and recommendation integrated system (DRIS) method to evaluate the nutritional status of an apple orchard, cv. Gala/MM106, at Vacaria, State of Rio Grande do Sul, Brazil. Treatments consisted of four levels of annual maintenance potassium fertilization. Data on fruit production and fruit pellicle color were restored from 1995 to 2000, as well as the data on leaf macro and micro-nutrient concentrations. The DRIS indices and nutritional balance index (NBI) for each nutrient were determined using three methods: Beaufils, Jones, and Elwali and Gascho. The results showed that (i) the NBI, calculated from the generated norms, were negatively correlated negative correlated with productivity and fruit coloration, and (ii) the DRIS method, described by Elwali and Gascho and using the F value, was the most suitable for apple tree orchards, because the NBI values obtained with this method best indicated the nutritional status of the plants and provided a more accurate nutritional diagnosis.

CARACTERES MACRO E MICROSCÓPICOS DE FOLHA DE LOURO

Denominado comumente de louro ou loureiro, Laurus nobilis L. é uma árvore de tronco liso, com muitos ramos e folhas, inflorescências amarelas e frutos globosos escuros. As folhas são nitidamente odoríferas e empregadas como condimento alimentar e como digestivo, carminativo e antiespasmódico na medicina popular. Estudos fitoquímicos identificaram componentes do óleo essencial, mucilagem, lactonas sesquiterpênicas, taninos e alcalóides. Em razão da relevância do louro na culinária e na fitoterapia, e à escassez de informações morfoanatômicas para o controle de qualidade, este trabalho tratou da caracterização macro e microscópica foliar dessa espécie. Folhas adultas foram fixadas, seccionadas à mão livre e submetidas à dupla coloração ou a testes microquímicos usuais. As folhas são alternas, simples, inteiras e oboval-lanceoladas. As células da epiderme têm contorno sinuoso e são revestidas por cutícula moderadamente espessada. Estômatos paracíticos ocorrem na face abaxial e alguns tricomas tectores unicelulares estão presentes. O mesofilo é dorsiventral e nele distribuem-se feixes vasculares de pequeno porte com extensão de bainha esclerenquimática. A nervura central possui secção biconvexa e o pecíolo é plano-convexo. Ambos são percorridos por um feixe vascular colateral, envolto por bainha esclerenquimática incompleta. Células secretoras, arredondadas e relativamente grandes, ocorrem na folha.

Growth, leaf nutrient concentration and photosynthetic nutrient use efficiency in tropical tree species planted in degraded areas in central Amazonia

The success of initial tree seedling establishment is related to the capture and use of primary resources such as light and nutrients. The selection of tree species with a greater potential to assimilate carbon and capacity to efficiently utilize nutrients and light would facilitate the revegetation of degraded areas, primarily where irradiance is high and soil nutrient availability low. We analyzed soil physical and chemical characteristics, survival, growth, photosynthesis, chlorophyll a fluorescence, leaf macro- and micro-nutrient content and photosynthetic nutrient use efficiency in young tropical tree species planted in degraded areas in central Amazonia. The species studied were: Bellucia grossularioides, Bombacopsis macrocalyx, Cecropia ficifolia, Cecropia sciadophylla, Chrysophyllum sanguinolentum, Eugenia cumini, Inga edulis and Iryanthera macrophyla. C. sanguinolentum, a late secondary species, exhibited the lowest survival rates, except when compared with B. grossularioides and C. sciadophylla. Photosynthesis varied between 34 and 264 nmol g −1 s −1 for the eight species; species of Cecropia had photosynthetic values eight times greater than C. sanguinolentum. For the photochemical efficiency of photosystem II, C. sanguinolentum presented the highest degree of photoinhibition as a result of an inefficient use of excess irradiance. Leaf macronutrient concentrations varied from 16 to 29, 0.4 to 1.0, 6 to 13, 7 to 22, 1.6 to 3.4 g kg −1 for N, P, K, Ca and Mg, respectively. For photosynthetic nutrient use efficiency, in general, the two species of Cecropia exhibited the highest values, while C. sanguinolentum presented the lowest macronutrient use efficiency. The two species of Cecropia had photosynthetic nitrogen use efficiency seven times greater than C. sanguinolentum. On these highly degraded soils we found that pioneer trees ( Cecropia) are better able to colonize than species from other successional stages. Trees on these degraded soils are primarily limited by P or micronutrients. Despite the remove of the O horizon, N does not appear to limit photosynthetic activity. From this we conclude that species of Cecropia possess ecophysiological mechanisms associated with carbon assimilation and nutrient use that determines success in early establishment and has potential to recuperate degraded areas, especially when compared to C. sanguinolentum. Early secondary species such as I. edulis and E. cumini could also be used with success in forest plantings to recuperate degraded areas when selecting for species, (1) efficient in the utilization of excess energy for photosynthesis, (2) efficient in the use of limited soil nutrients and (3) with high survival and growth rates.

Fertiliser application affects susceptibility of chrysanthemum to western flower thrips – abundance and influence on plant growth,photosynthesis and stomatal conductance

SummaryWe report the influence of plant fertility, principally nitrogen (N) levels, on plant growth, gas exchange and herbivore abundance in chrysanthemum (Dendranthema grandiflora Tzvelev 'Charm') infested with western flower thrips [WFT; Frankliniella occidentalis (Pergande)]. Four levels of a commercial, soluble fertiliser "15-16-17" (elemental analysis: 15N-6.7P-14.1K) were tested at: 0,38,75 and 375 mg l-1 N [0N, 35N, 75N, 375N], which represented 0%, 10%, 20% and 100% of the recommended N-fertilisation rate, respectively. Adult and immature WFT were most abundant at the highest fertility level (375N). At moderate (38N and 75N) to high fertility (375N), WFT infestation depressed plant vegetative and reproductive growth, and altered carbohydrate partitioning. WFT-infested plants had reduced flower bud dry mass (DM) and flower bud number compared to uninfested plants. While WFT infestation reduced leaf area and leaf mass, the specific leaf area (SLA; i.e., leaf thickness) was not affected. However, high fertility plants had greater reproductive and vegetative biomass, greater leaf elemental levels (N, P, Ca, Mg, B, Fe, Mn, Cu and Zn) and a higher SLA (i.e., thinner leaves) than low fertility (0N) plants. Leaf stomatal conductance (gs) was more sensitive to WFT damage than net photosynthesis (Pn). WFT damage caused a reduction in Pn in young and physiologically mature leaves at the highest fertility level, whereas gs was reduced in young, physiologically mature and older basal leaves of plants damaged by WFT at moderate to high fertility. WFT infestation had no effect on leaf macro- and micro-elements, ethylene production or chlorophyll levels. WFT damage reduced vegetative and reproductive growth primarily through reduced Pn and gs.

Nutrient Requirements of Ahipa, a Tuberous-Root Crop

Ahipa is a legume crop of great potential for the production of raw materials (starch, sugar, oil, and proteins) for industrial use. Its ability to fix atmospheric N2 in association with rhizobia and the tolerance to insects makes it an attractive option for low input agriculture schemes. There is little information available on nutrient requirements of ahipa and none about its behavior in Mediterranean soils. Leaf macro and micronutrient concentration in ahipa field-grown plants was compared with critical levels reported for other legume crops. Low leaf phosphorus (P) and potassium (K) concentration, as well as leaf zinc (Zn) and copper (Cu) might show limiting conditions for growth and productivity in some Mediterranean soils. The evolution of N, P, and K uptake and nutrient distribution in different plant parts was studied in ahipa under field conditions. At harvest, seeds showed high N accumulation whereas roots and pod-shells were the main recipients for P and K. The amount of nutrients removed by harvested roots and seeds was calculated in 67 kg N ha−1, 13.7 kg P ha−1, and 80.2 kg K ha−1.

Seasonal changes in durian leaf and soil mineral nutrient element content

The 3–4 year monitoring study showed that fluctuations in durian (Durio zibethintts Murray) leaf and soil nutrient element levels were closely related to seasonal changes in the crop phenology. The leaf sampling method was standardized taking the 5th and 6th mature green leaf from the shoot tip. The best sampling time was determined to be in November where the coefficient of variability for most nutrient elements were the lowest at or lower than 20%. Tentative standards for durian leaf nutrient elements were set up taking the 95% confidence interval of the means at this sampling stage. All the leaf macro elements, nitrogen (N), phosphorus (P), potassium (K), sulfur (S), and the micro elements, zinc (Zn), manganese (Mn), copper (Cu), and iron (Fe) declined or were lower during fruit set and development from September to end of fruit harvest in January. Leaf N was also the lowest in July and leaf P at the tail end of harvest. Soil N, P, and the bases K, Ca, and Mg also exhibited similar trends, lower during fruit development especially in October‐November and were lower during active leaf flushing from March to May.