Efficiency of nitrogen use by sesame genotypes under brazilian semi-arid conditions

Nitrogen (N) is an essential macronutrient for plant growth and rate applications can influence the performance of sesame, and when applied in excess can cause nitrogen loss in the environment, and consequently make the cost of production more costly to the producer. Therefore, the objective of this work was to evaluate the efficiency of nitrogen use by different cultivars of irrigated sesame seeds under the edaphoclimatic conditions of the northeastern semi-arid region in two harvests. The experiments were carried out from February to May (1st harvest) and from July to October (2nd harvest) in 2016. The treatments were arranged in a split plot scheme, in which the plots were the five nitrogen doses (0, 30, 60, 90 and 120 kg ha-1), and in the subplots, the four sesame genotypes (CNPA G2, CNPA G3, CNPA G4 and BRS Seda), the design was in randomized complete blocks with four replications. The nitrogen use efficiency assessments evaluated were: agronomic efficiency (AE), physiological efficiency (PE), agrophysiological efficiency (APE), recovery efficiency (RE) and efficiency of use (EU). The rate that provided the greatest efficiency of use was 30 kg ha-1 of N applied. The cultivar BRS Seda had greater efficiency of use in relation to the other cultivars studied. The crop that had better efficiency of use was the 2nd agricultural harvest.

NPK and sodium content in sesame under salt stress and nitrate/ammonium fertilization / Teores de NPK e sódio no gergelim sob estresse salino e adubação com nitrato/amônio

This study aimed to evaluate the effects of saline water irrigation and fertilization with different nitrate/ammonium proportions on the contents of nitrogen (N), phosphorus (P), potassium (K+) and sodium (Na+) and Na+/K+ ratio in the sesame cv. CNPA G3, through an experiment conducted in drainage lysimeters under greenhouse conditions, in eutrophic Regolithic Neosol with sandy loam texture, in the municipality of Campina Grande-PB, Brazil. Treatments were distributed in randomized blocks, in 5 x 5 factorial scheme, with three replicates, relative to five levels of irrigation water salinity - ECw (0.6; 1.2; 1.8; 2.4 and 3.0 dS m-1) and five nitrate/ammonium proportions - NAP (200:0,150:50, 100:100, 50:150, 0:200 mg kg-1 of NO3 --N/NH4+-N). Increasing ECw levels caused increment in Na+ contents and reduction in N, P and K+ contents in leaf and stem tissues of the sesame cv. CNPA G3. The increase in the Na+/ K+ ratio in leaves and stem of sesame under irrigation with ECw water up to 3.0 dS m-1 can be considered as a mechanism of tolerance to salt stress. There was interaction between the factors (ECw x NAP) for the N content in the leaf tissues, and its highest accumulation was obtained with ECw of 0.6 dS m-1 and NO3 --N/NH4 +-N proportion of 200:0 mg kg-1.

Objetivou-se, neste trabalho, avaliar os efeitos da irrigação com águas salinas e adubação com diferentes proporções de nitrato e amônio sobre os teores de NPK, sódio e relação Na/K no gergelim cv. CNPA G3, em experimento conduzido em lisímetros de drenagem sob condições de casa de vegetação, no Neossolo Regolítico Eutrófico, textura franco-arenosa, no município de Campina Grande, PB. Os tratamentos foram distribuídos em blocos casualizados, em esquema fatorial 5 x 5, com três repetições, referentes a cinco níveis de condutividade elétrica da água de irrigação ­ CEa (0,6; 1,2; 1,8; 2,4 e 3,0 dS m-1) e cinco proporções de nitrato e de amônio - PNA (200:0, 150:50, 100:100, 50:150, 0:200 mg kg-1 de N-NO3-/N-NH4+). Níveis crescentes de CEa promoveu aumento nos teores de Na+ e diminuição nos teores de N P K nos tecidos foliares e caulinar do gergelim cv. CNPA G3; o aumento na relação Na+/K+ nas folhas e caule do gergelim sob irrigação com água de CEa até 3.0 dS m-1 pode ser considerado como mecanismo de tolerância ao estresse salino; houve interação entre os fatores (CEa x PNA) para teor de nitrogênio nos tecidos das folhas, sendo o maior acúmulo obtido com CEa de 0,6 dSm-1 e proporções de 200:0 mg kg-1 de N-NO3- e N-NH4+.

Physiological indices and production of sesame under salt stress and nitrate/ammonium proportions / Índices fisiológicos e produção do gergelim sob estresse salino e proporções de nitrato e amônio

In semi-arid regions, the occurrence of water with high concentration of salts is common, which compromises the growth and consequently the production of crops. Thus, this study aimed to evaluate the gas exchanges and production of sesame, cv. CNPA G3, irrigated with saline water and fertilized with different proportions of nitrate and ammonium, in an experiment conducted using lysimeters in a greenhouse in the municipality of Campina Grande-PB, Brazil. The treatments were arranged in randomized blocks and analyzed in a 5 x 5 factorial scheme, with three replicates, relative to five levels of electrical conductivity of the irrigation water ­ ECw (0.6, 1.2, 1.8, 2.4 and 3.0 dS m-1) and five proportions of nitrate/ammonium - NO3 -/NH4 + (200/0, 150/50, 100/100, 50/150 and 0/200 mg of N kg-1 of soil). Irrigation with water of salinity level higher than 0.6 dS m-1 promoted negative effect on gas exchanges and production components of the sesame cv. CNPA G3. Fertilization with N exclusively in the form of NH4 + promoted increment in CO2 concentration and reduction in its assimilation rate and instantaneous carboxylation efficiency. The highest rate of CO2 assimilation, transpiration and instantaneous carboxylation efficiency were obtained when the plants were irrigated with water of 0.6 dS m-1 and fertilization with 200/0 of NO3 -/NH4 +. Increasing levels of water salinity promoted a decrease in the total seed mass, regardless of the proportion of NO3 -/NH4 +. The sesame cv. CNPA G3 is classified as sensitive to salt stress from the electrical conductivity of water of 0.6 dS m-1.

Nas regiões semiáridas é comum a ocorrência de águas com elevada concentração de sais que comprometem o crescimento e consequentemente a produção das culturas. Deste modo, objetivou-se avaliar as trocas gasosas e a produção do gergelim cv. CNPA G3 irrigado com águas salinas e adubado com diferentes proporções de nitrato e amônio em um ensaio conduzido em lisímetros dispostos em casa de vegetação no município de Campina Grande, PB. Os tratamentos foram distribuídos em blocos ao acaso e analisados em esquema fatorial 5 x 5, com três repetições, relativos a cinco níveis de condutividade elétrica da água de irrigação ­ CEa (0,6; 1,2; 1,8; 2,4 e 3,0 dS m-1) e cinco proporções de nitrato e amônio - NO3 -/NH4 + (200/0; 150/50; 100/100; 50/150 e 0/200 mg de N kg-1 de solo). A irrigação com água de salinidade superior a 0,6 dS m-1 promoveu efeito negativo sobre as trocas gasosas e os componentes de produção do gergelim cv CNPA G3. A adubação com N exclusivamente na forma de NH4 + proporcionou incremento na concentração de CO2 e redução na taxa de assimilação de CO2, eficiência instantânea de carboxilação. A maior taxa de assimilação de CO2, transpiração e eficiência instantânea de carboxilação foram obtidas quando as plantas foram irrigadas com água de 0,6 dS m-1 e adubação com 200/0 de NO3 -/ NH4 +. Níveis crescentes de salinidade da água promoveram diminuição na massa total de sementes, independente da proporção de NO3 - e NH4 +. O gergelim cv. CNPA G3 foi classificado como sensível ao estresse salino, a partir da condutividade elétrica da água de 0,6 dS m-1.

Variability and Genetic Divergence in Sesame (Sesamum Indicum L.).

A collection of 280 sesame genotypes of different ecogeographical origin was evaluated using augumented block design along with four checks. Analysis of variance revealed the presence of significant variability among genotypes for all the characters studied. The highest heritability coupled with highest genetic advance was observed for capsules per plant indicating the predominance of additive gene effects. Whereas lower estimates of heritability and genetic advance was revealed for days to maturity and capsule length suggesting the presence of nonadditive gene action for controlling these traits. Based on diversity the genotypes were grouped into 12 clusters and highest intercluster distance was observed between cluster VI & XII followed by cluster VI & IX, cluster II & VI and cluster III & IV. Among the traits studied capsule per plant and plant height contributed maximum for studying divergence while no contribution from capsule length. Hybridization involving genotypes of cluster VI with KMR 3 (cluster XII) may result in exploiting maximum heterosis to produce desirable transgressive segregants for crop improvement.