Enhancing Pinus pinea cone production by grafting in a non-native habitat

New Forests - Pinus pinea is an interesting species for its valued pine nuts. Despite the high demand for this nut, the species is mostly harvested from natural forests, because the time elapsed...     

Clinical efficacy of the acyclic nucleoside phosphonate 9-(2-phosphonylmethoxypropyl)-2,6-diaminopurine (PMPDAP) in the treatment of feline immunodeficiency virus-infected cats

In in vitro studies, the acyclic nucleoside phosphonate 9-(2-phosphonylmethoxypropyl)-2,6-diaminopurine (PMPDAP) inhibited the replication of feline immunodeficiency virus (FIV). No information about its clinical efficacy is available so far. The aim of this prospective placebo-controlled, double-blinded study was to evaluate the antiviral efficacy of PMPDAP in cats naturally infected with FIV. Twenty cats were randomly assigned to two treatment groups receiving either PMPDAP (25 mg/kg) or placebo twice per week subcutaneously for 6 weeks. The general health status (Karnofsky's score), clinical signs, laboratory, immunological, and surrogate parameters were evaluated. No significant differences were found between PMPDAP- and placebo-treated cats, although cats treated with PMPDAP showed a tendency for improvement in their Karnofsky's score and clinical signs. Haematological side effects were noted in the PMPDAP-treated cats. Thus, PMPDAP may be an option in treating cats if it becomes available for veterinarians, but side effects have been monitored.     

Morpho-physiological traits associated with maize crop adaptations to environments differing in nitrogen availability

The use of genotypes with improved performance for nitrogen (N) capture and use would be of great benefit through reducing production costs and pollution risks in maize cropping. The identification of morpho-physiological traits responsible for a better behavior in a target N environment is useful for cultivar selection, and become crucial for maize breeding improvement. This study analyzed, in a set of Argentinean commercial hybrids of maize, the grain yield (GY) variability in response to soil N availability at several locations representative of the main maize production region of Argentina during 2003–2004 growing season. The objectives of this work were to: (i) detect environmental groups for GY responses, (ii) identify morpho-physiological traits that were associated to winner genotypes in each detected environmental group, and (iii) assess genetic correlations between those traits. To generate more variation in soil N availability two N-fertilizer rates were applied in each experimental site (0 and 250 kg N ha⁻¹, except for Balcarce where only 250 kg N ha⁻¹ was tested). Morpho-physiological traits included in the analysis were related to N and radiation capture, use and partitioning, plant architecture, and leaf senescence. Grain yield components were also included. As expected, environment (E) effect explained the higher portion of GY variation (i.e., 82%), but genotype (G) and G × E interaction (GE) also significantly contributed (i.e., 9% each). Three environmental groups for GY were identified according to N availability. Morpho-physiological traits related to resource capture, use, and partitioning during the post-silking period are proposed as desirables for broad adaptation. In turn, a high N partitioning to grains after silking was associated with good hybrid behavior under high N availability and warm climate. On the other hand, a better grain yield performance when N became more limited appeared strongly related to an efficient canopy to sustain resource capture up to maturity. More studies are required in a wide range of environments to confirm identified traits and underlying physiological mechanisms. Nevertheless, our findings highlight the existence of differences in ideal plant-type for environments differing in N availability to be considered in maize breeding programs.     

Multivariate analysis of morphological characters in Setaria leiantha Hackel

Summary Continuous characters related to plant morphology and seed production were measured in eight populations of Setaria leiantha. Phenotypic variation for 12 traits was analyzed by multivariate methods. A canonical variate analysis provided a preliminary criteria for distinguishing the populations. The first three canonical components account for 93% of the total variance. Seed weight per ear was the most important character to discriminate among populations. The preliminari groups formed will serve as centers of diversity for future collections.     

Salt tolerance variability amongst Argentine Andean potatoes (Solanum tuberosum L. subsp.andigena)

Summary Salt tolerance in Andean potatoes can be a source for this trait in cultivated potatoes or be exploited to expand potato cultivation to more marginal areas. The purpose of this study was to determine salt tolerance in twelve Argentine Andean potato varieties through the response of nodal segments cultured in vitro and to evaluate whether changes in Na⁺, K⁺ or proline accumulation associate with salt tolerance. Genotypes Bianca, Airampia, Sisa Sani and Cuarentilla were the most tolerant. The most susceptible varieties were Balcacha, Runa Rosada, Collareja, Overa, Bianca Redonda and Papa Baya, while Cuarentona and Colorado Ml comprised an intermediate group. These results indicate that variability for salt tolerance exists in this germplasm, and highlights its potential use in breeding programmes. No association was found between the salt tolerance rating and changes in K⁺, Na⁺ and proline accumulation in a salt gradient, thus precluding the use of these parameters as predictors for salt tolerance of these species in in vitro studies.     

Effects of stone pine (Pinus pinea L.) plantation spacing on initial growth and conelet entry into production

New Forests - Stone pine (Pinus pinea L.) is well-known for its fruits, the pine nuts, which are considered a delicacy and are the most expensive dry fruits in the world. This fruit is harvested...     

Analysis of flowering dynamics heritability in the perennial warm‐season grass Paspalum dilatatum

Understanding the flowering cycles of perennial warm‐season grass species may be very important to the design of management practices and breeding. However, developmental dynamics are not well understood. As most plant traits associated with flowering dynamics do not follow a normal distribution, the use of general linear models to describe and compare these variables might be misleading. The aims of this study were (i) to find a methodology to compare panicle accumulation curves and (ii) to estimate heritabilities for flowering curve attributes. Panicle counts were recorded during a complete flowering cycle on a diverse collection of dallisgrass (Paspalum dilatatum). We compared the efficiency of different linear mixed models based on whole plot or individual plant data; then, we adjusted nonlinear regression curves for individual plants to estimate several curve attributes and compared this approach to the area under the curve. Finally, we calculated the broad‐sense heritabilities of the estimated curve parameters. The following reproductive curve attributes were obtained: panicle production potential, panicle accumulation rate and days until 3, 5, 10 and 15 panicles. We found that monitoring individual plants is more efficient when studying flowering attributes. Significant differences among genotypes for several flowering cycle attributes were found. Heritabilities were very high for all flowering cycle initiation and duration attributes. We also showed that the number of days until the emergence of a given low number of panicles can be used as a highly heritable measure to characterize flowering cycles.     

Protocol for automating error removal from yield maps

Precision Agriculture - Yield mapping is one of the most widely used precision farming technologies. However, the value of the maps can be compromised by the presence of systematic and random...     

Oil quality and sugar content of peanuts (Arachis hypogaea) grown in Argentina: their relationship with climatic variables and seed yield

The ratio of oleic to linoleic acids (O/L) and the tocopherol content are important features in determining peanut (Arachis hypogaea) seed shelf life. Soluble carbohydrates are known to be important precursors in roasted peanut flavor. The chemical qualities of Argentine grain are different from those of other countries, but no previous studies that associate grain quality and environmental parameters have been performed. Relationships were determined between O/L, tocopherol and sugar contents, and variations in temperature and rainfall during the grain filling period of Florman INTA peanuts. Dry seed yield was used as another explanatory variable. Multiple regression procedure gave mean temperature (positive coefficient) and total precipitation (negative coefficient) as the explanatory variables for variations in O/L. Total precipitation and dry seed yield (both negative coefficients) were found to be predictor variables for tocopherol and sugar contents. Total precipitation was an explanatory variable included in all of the linear regression models obtained in this study.