Resposta da produtividade de grãos e outras características agronômicas do trigo EMBRAPA-22 irrigado ao nitrogênio em cobertura

As doses e a época de aplicação do nitrogênio (N) podem influenciar as características agronômicas do trigo (Triticum aestivum L.) irrigado e, conseqüentemente, a produtividade de grãos. Neste sentido, foram instalados dois experimentos na Estação Experimental da Universidade Federal de Viçosa, localizada em Coimbra (MG), em 1995 e 1996. Os tratamentos foram constituídos pela combinação de quatro doses de N (30, 60, 90 e 120 kg ha-1), quatro formas de parcelamento (dose total aos 20 dias da emergência (DAE); ½ aos 20 + ½ aos 40 DAE; 1/3 aos 20 + 2/3 aos 40 DAE e 2/3 aos 20 + 1/3 aos 40 DAE) e uma testemunha (sem N em cobertura), dispostos em esquema fatorial 4 x 4 + 1, no delineamento em blocos casualizados com quatro repetições. A altura e o acamamento das plantas, a biomassa seca, o índice de colheita, a massa de mil grãos, o peso hectolítrico e a produtividade de grãos foram influenciados pelas doses de N. Em 1996, o número de espigas por metro quadrado e o número de perfilhos férteis por planta diminuíram, em conseqüência do acamamento precoce das plantas, enquanto o número de grãos por espiga e o número de grãos por metro quadrado aumentaram com o incremento nas doses de N. As formas de parcelamento influenciaram somente o acamamento das plantas

The SPTPoL extended cluster survey

We describe the observations and resultant galaxy cluster catalog from the 2770 deg2 SPTpol Extended Cluster Survey (SPT-ECS). Clusters are identified via the Sunyaev-Zel'dovich (SZ) effect and confirmed with a combination of archival and targeted follow-up data, making particular use of data from the Dark Energy Survey (DES). With incomplete follow-up we have confirmed as clusters 244 of 266 candidates at a detection significance ξ ≥ 5 and an additional 204 systems at 4 4 threshold, and 10% of their measured SZ flux. We associate SZ-selected clusters, from both SPT-ECS and the SPT-SZ survey, with clusters from the DES redMaPPer sample, and we find an offset distribution between the SZ center and central galaxy in general agreement with previous work, though with a larger fraction of clusters with significant offsets. Adopting a fixed Planck-like cosmology, we measure the optical richness-SZ mass (l - M) relation and find it to be 28% shallower than that from a weak-lensing analysis of the DES data-a difference significant at the 4σ level-with the relations intersecting at λ = 60. The SPT-ECS cluster sample will be particularly useful for studying the evolution of massive clusters and, in combination with DES lensing observations and the SPT-SZ cluster sample, will be an important component of future cosmological analyses

Detection of CMB-cluster lensing using polarization data from SPTpol

We report the first detection of gravitational lensing due to galaxy clusters using only the polarization of the cosmic microwave background (CMB). The lensing signal is obtained using a new estimator that extracts the lensing dipole signature from stacked images formed by rotating the cluster-centered Stokes Q U map cutouts along the direction of the locally measured background CMB polarization gradient. Using data from the SPTpol 500     deg 2 survey at the locations of roughly 18 000 clusters with richness λ ≥ 10 from the Dark Energy Survey (DES) Year-3 full galaxy cluster catalog, we detect lensing at 4.8 σ . The mean stacked mass of the selected sample is found to be ( 1.43 ± 0.40 ) × 10 14 M ⊙ which is in good agreement with optical weak lensing based estimates using DES data and CMB-lensing based estimates using SPTpol temperature data. This measurement is a key first step for cluster cosmology with future low-noise CMB surveys, like CMB-S4, for which CMB polarization will be the primary channel for cluster lensing measurements

Utilization of potatoes in the tropics

Meeting: International Society for Tropical Root Crops Symposium, 4th, 1-7 Aug. 1976, Cali, COIn IDL-133

Increasing Wheat Yields Sustainably through Agronomic Means

This paper examines common factors that constrain wheat yields: insufficient nutrients (using nitrogen as an example); problems of late planting and poor crop establishment; suboptimal water management;lodging; and weeds. The authors suggest agromonic practices/ including tillage practices, rotations, and input management potions that can ameliorate important constraints and sustainably improve yields. Examples are drawm largely from rice-wheat systems in the Indo-Gangetic Plains and from wheat systems in northwestern Mexico. These examples indicate that there is still considerable potential for raising wheat yields in a sustainable manner and meeting rapidly expanding demand for wheat in developing countries

Identifying factors that determine kernel number in wheat.

Understanding variation in kernel number per unit area (KNO) is of major importance in understanding yield and in identifying opportunities to increase yield potential. Factors that determine KNO should therefore be identified considering wide ranges in both crop and environmental conditions. Several field experiments with various spring wheat cultivars were conducted over three years in Mexico. Wide ranges in crop and environmental conditions were obtained by varying N application rates and timing and by different planting dates and locations. Crop development from emergence (DC10) to physiological maturity (DC90) was divided in three phases, with the intermediate phase II ranging approximately from early booting (DC40) to final anthesis (DC70). A photothermal quotient (PTQ) during phase II failed to explain the variation in KNO. Biomass at anthesis explained 72% of the variance, but could not explain some deviant situations and the relation was strongly cultivar specific. Biomass accumulation during phase II more accurately (80%) explained the deviant situations, except one particular location, and cultivar differences became even more pronounced. At this location KNO was also well explained by non-grain spike weight at a week from anthesis, with a constant number of kernels per unit spike dry matter, while differences among cultivars tended to disappear. Factors that are identified to determine KNO are discusse