Conditions Of Low Availability Research Articles

Effect of rainfall variability on the production of Vigna unguiculata (L.) Walp. in the semi-arid region of Paraíba

Agricultural production in semi-arid areas of the globe is dependent on species adapted to conditions of low availability of resources, such as water. Cowpea (Vigna unguiculata L. Walp.) is a vegetable widely grown in regions with water restrictions, however, even with its good adaptability, it is vulnerable to the effects of prolonged droughts. In this sense, this research aimed to analyze the influence of rainfall patterns on the production dynamics of cowpea during the period of fifteen years (2002-2016) in the municipality of Conceição, Paraíba, Brazil. A correlation matrix was used to analyze the influence of precipitation on the production variables of the cowpea crop, as well as the relationship between these variables. Subsequently, the Principal Component Analysis (PCA) was carried out. The results showed a strong reduction in the production variables of cowpea from the year 2012, which is due to the reduction of rainfall in this period and was proven through the correction matrix, which showed a positive correlation of rainfall mainly with the planted and harvested area. The PCA recorded 91.02% of explanation in the first two axes, and demonstrated that for production and productivity, other factors in addition to good rainfall levels are necessary to increase the productive results of cowpea in the municipality.

Seed characterization and early nitrogen metabolism performance of seedlings from Altiplano and coastal ecotypes of Quinoa

BackgroundEarly seed germination and a functional root system development during establishment are crucial attributes contributing to nutrient competence under marginal nutrient soil conditions. Chenopodium quinoa Willd (Chenopodiaceae) is a rustic crop, able to grow in marginal areas. Altiplano and Coastal/Lowlands are two representative zones of quinoa cultivation in South America with contrasting soil fertility and edaphoclimatic conditions.In the present work, we hypothesize that the ecotypes of Quinoa from Altiplano (landrace Socaire) and from Coastal/Lowland (landrace Faro) have developed differential adaptive responses in order to survive under conditions of low availability of N in their respective climatic zones of Altiplano and Lowlands. In order to understand intrinsic differences for N competence between landraces, seed metabolite profile and germinative capacity were studied. Additionally, in order to elucidate the mechanisms of N uptake and assimilation at limiting N conditions during establishment, germinated seeds of both landraces were grown at either sufficient nitrate (HN) or low nitrate (LN) supply. We studied the photosynthetic performance, protein storage, root morphometrical parameters, activity and expression of N-assimilating enzymes, and the expression of nitrate transporters of roots in plants submitted to the different treatments.ResultsSeeds from Socaire landrace presented higher content of free N-related metabolites and faster seed germination rate compared to Faro landrace. Seedlings of both ecotypes presented similar physiological performance at HN supply, but at LN supply their differences were exalted. At LN, Socaire plants showed an increased root biomass (including a higher number and total length of lateral roots), a differential regulation of a nitrate transporter (a NPF6.3-like homologue) belonging to the Low Affinity Transport System (LATS), and an upregulation of a nitrate transporter (a NRT2.1-like homologue) belonging to the High Affinity nitrate Transport System (HATS) compared to Faro. These responses as a whole could be linked to a higher amount of stored proteins in leaves, associated to an enhanced photochemical performance in Altiplano plants, in comparison to Lowland quinoa plants.ConclusionsThese differential characteristics of Socaire over Faro plants could involve an adaptation to enhanced nitrate uptake under the brutal unfavorable climate conditions of Altiplano.

GENETIC DIVERSITY IN ARABICA COFFEE GROWN IN POTASSIUM-CONSTRAINED ENVIRONMENT

Potassium is a source of non-renewable natural resource, and is used in large quantities in coffee fertilization through basically imported formulations in the form of potassium chloride. An alternative to make production systems more sustainable would be obtaining cultivars more efficient in the use of this nutrient. This study aimed to evaluate the genetic diversity among 20 cultivars of coffee, in conditions of low availability of potassium to identify the best combinations for composing future populations to be used in breeding programs. The experiment was arranged in a randomized block design with three replications of nutrient solution. Agronomic characteristics and efficiencies of rooting, absorption, translocation, biomass production and potassium utilization were evaluated. The clustering analysis was based on the unweighted pair group method with arithmetic mean clustering algorithm (UPGMA) and canonical variables. Variability was observed for most treatments. The multivariate procedures produced similar discrimination of genotypes, with the formation of five groups. Hybridizations between the cultivar Icatu Precoce IAC 3283 with cultivars Catuaí Amarelo IAC 62, Araponga MG1, Caturra Vermelho IAC 477, Catuaí Vermelho IAC 15, Rubi MG 1192 and Catucaí 785/15, and between the cultivar Tupi IAC 1669-33 with cultivars Icatu Vermelho IAC 4045, Acaiá Cerrado MG 1474 and Oeiras MG 6851 are the most promising for obtaining segregating populations or heterotic hybrids in breeding programs aiming more efficiency in potassium utilization.

Analysis of the means of forest harvesting in the Federation of Bosnia and Herzegovina

The development of technology and the means of labour in the technological process of forest harvesting in FBiH mainly depends on the factors related to the specific manner of forest management. The dominant share of mixed tall forests with natural regeneration, the selective manner of management and rather difficult natural conditions have resulted in the application of the cut-to-length method and to a lesser extent, the tree-length and semi-tree-length methods. On the basis of expert classification of the development phases in forest harvesting, it can be noted that wood assortment production in FBiH is currently partially mechanised. With the aim of defining measures for increasing productivity, lowering the costs and a greater humanisation of work, there has been an analysis of the current state of the means of work in all three phases of forest harvesting. The analysis included the following parameters: number of means in different phases, the type, the average age, ownership and technical planned obsolescence. All the data were collected through a survey which included all stakeholders (cantonal forest companies and private contractors). The results showed a satisfactory state only when chainsaws are concerned, i.e. the rather cheap tools. Other equipment (adapted tractors, skidders, trucks, etc.) has largely reached planned obsolescence. Their old age results in a low level of utilisation, i.e. an insufficient amount of working hours per year which eventually leads to a decrease in productivity and increase in expenses. Based on the data, it can be concluded that it is necessary to begin the process of new mechanisation procurement and the replacement of existing, time-worn and technologically obsolete machines with new ones. At the same time, it is clear that, in the conditions of low availability of investment capital and cheap labour force, this has to be a gradual process. In relation with this, the process should start in the most expensive phase - timber extraction, i.e. the phase in which the economic efficiency is unquestionable.

Controls on emergent macrophyte composition, abundance, and productivity in freshwater Everglades wetland communities

The relationships between tissue nutrient content, species-specific productivity, and species abundance were investigated in seven emergent wetland species to determine how important a functional role phosphorus availability plays in controlling specific composition, abundance, and productivity in two naturally occurring Everglades wetland communities (sawgrass and wet prairie). Evidence from our tissue nutrient data suggest that the dominant taxa in each of these communities (Cladium jamaicense in the sawgrass community andEleocharis spp. in the wet prairie community) are strongly limited by phosphorus and that the availability of this nutrient is important in controlling the productivity of each of these taxa.Cladium jamaicense had a significantly higher molar N:P ratio than either of the two other species, which were found to co-exist in the sawgrass community, suggesting that this species has extremely low requirements for phosphorus and, consequently, may be able to most effectively use phosphorus under conditions of low availability. Nutrient availability also seemed to be important toPeltandra virginica, although it seems that this species may be limited by nitrogen as opposed to phosphorus. Unlike bothC. jamaicense andP. virginica, nutrient availability (either nitrogen or phosphorus) was insufficient to explain patterns of productivity or abundance forP. cordata, suggesting that some other environmental factor is more important for this species. In the wet prairie community, bothEleocharis spp. and the second most abundant species,Sagittaria lancifolia, had relationships that suggested that the productivity or abundance of both of these species is regulated by phosphorus availability. In contrast,Panicum hemitomon, an important Everglades plant, did not show either productivity or abundance patterns that could be adequately explained in terms of nutrient availability. It seems more likely that, similar toP. cordata in the sawgrass community, some other environmental variable is more important than phosphorus availability—although the high N:P ratios inP. hemitomon leaf tissue do suggest that this species is phosphorus-limited. Furthermore, leaf tissue N:P data also suggested thatHymenocallis palmeri may be limited entirely by nitrogen, rather than phosphorus.

Ammonium Assimilation in Leaf Tissues of Vigna mungo

Summary The main route of ammonia assimilation in higher plants is through the formation of glutamate and glutamine which are the key metabolites in organic nitrogen metabolism, but the GS/GOGAT pathway works more efficiently under conditions of low availability of ammonia. This has been shown by the Km values for NH 4 + of GS and GDH. This finding is further substantiated by the use of an inhibitor, 1-methionine-dl-sulphoximine (MSO) for glutamine synthetase. This inhibitor blocks assimilation of NH 4 + which is not utilized by glutamate dehydrogenase, and thus gets accumulated in the tissue.

Effect of Ovariectomy on Blood Concentration of Orally Administered Triolein I131 in Bitches on Low and Moderate Fat Intake.

SummaryTriolein I131 was administered to castrate and intact female beagles maintained on 2 levels of dietary fat. Castrate bitches were found to have a greater maximum percentage of administered radioactivity in circulation than intact females. Curves representing blood radioactivity plotted against time were similar after castration to those of some conditions in the human in which deranged lipid metabolism is implicated. Curves produced under conditions of low availability of dietary fat become erratic and presented only slightly different mean peak values when intact and castrate animals were compared.