Edades de corte e incidencia de enfermedades de dos sorgos forrajeros y sus rendimientos en materia seca y proteina bruta

Two forage sorghum hybrids ( ATx 623 X GL and FS25A) were grown from April 1985 to February 1987 at the Agricultural Experiment Station of the University of Puerto Rico at Lajas, Puerto Rico to determine the influence of maturity stage increases of 10 days (from the 45th to the 85th day) and how the presence and severity of foliar diseases affect the dry forage and crude protein yields. Dry matter content was higher for FS25A (16.1%) than for ATx 623 X GL (14.9%) whereas total yield for dry matter (DMY) was higher for ATx 623 X GL (3.84 t/ha) than for FS25A (3.51 t/ha). Both content and yield of dry matter increased with maturity stage in both genotypes. The sorghum hybrids did not differ significantly in crude protein content (CPC), but crude protein yield (CPY) was higher for ATx 623 X GL (421.6 kg/ha) than for FS25A (358.9 kg/ha). CPC declined with increased plant maturity. Foliar diseases appeared to limit DFY and CPY in both sorghum hybrids. Downy mildew, leaf blight, rust, grey leafspot, and zonate leafspot appeared seasonally. Leaf blight and downy mildew were the most prevalent from January to May, grey leafspot from May to September, and zonate leafspot from September to November. Rust was severe during all seasons.Se llevo a cabo un estudio con dos híbridos de sorgo forrajero (ATx 623 X GL y FS25A) de abril de 1985 a febrero de 1987 en la Subestación Experimental Agrícola de Lajas para medir la influencia sobre la producción de etapas de corte cada 10 días (desde el 45to al 85 to día) y como la incidencia de enfermedades afecta el rendimiento de forraje seco y proteína bruta. El contenido medio global de materia seca fue mayor en FS25A (16.1%) que en ATx 623 X GL (14.9). Lo contrario ocurrió con el rendimiento de forraje seco, ya que se obtuvo un rendimiento mayor con ATx 623 X GL (3.84 t./ha.) que con FS25A (3.51 t./ha.). El rendimiento de forraje seco y el contenido de materia seca aumentaron a medida que el forraje maduro. Las diferencias entre ambos híbridos en contenido medio de proteína bruta no fueron significativas. No obstante, la media ponderada para el rendimiento de proteína bruta total fue mayor para ATx 623 X GL (421.6 kg./ha.). El contenido y el rendimiento total de proteína bruta disminuyeron significativamente a medida que la etapa de corte aumentó de 45 a 85 días. Los rendimientos de forraje seco y de proteína bruta total también disminuyeron en ambos híbridos debido a la incidencia de enfermedades. Estas enfermedades fueron anublo lanoso ("downy mildew"), tizón ("leaf blight"), roya ("rust"), y mancha foliar ("zonate leafspot"). La época del año fue un factor determinante para la presencia de estas enfermedades. De enero a mayo la enfermedad más prevaleciente fue el anublo lanoso. Sin embargo, de mayo a julio predominó la mancha cercospórica y de septiembre a noviembre la mancha foliar

Requisitos de riego para sorgo en las costas sur y norte de Puerto Rico

Net irrigation requirements (NIR) of sorghum were estimated for three crop durations (3, 3.5 and 4 months), and 5 planting dates at the Fortuna Agricultural Experiment Substation, Juana Díaz, in the south coast of Puerto Rico and the Isabela Agricultural Experiment Substation, in the north coast of Puerto Rico. Modified Blaney-Criddle model was used to estimate monthly consumptive use (CU) with the temperature and rainfall data for these two locations. CU and NIR were highest at Fortuna than at Isabela for all three crop durations. For the January planting, the monthly NIR range (in) was 2.57 to 3.83 for 90 days, 0.71 to 3.83 for 3.5 months and 2.13 to 4.24 for 120 days at Fortuna; and 1.53 to 2.76 for 3 months; 0.00 to 2.76 for 105 days; 1.18 to 3.03 for 4 months at Isabela. Seasonal NIR (in) was 9.36 for 3 months, 11.13 for 3.5 months, 12.79 for 120 days at Fortuna compared with 6.95 for 3 months, 7.40 for 105 days, 8.80 for 4 months at Isabela. At both locations minimum NIR was observed in March for 3 months and in April for 3.5 and 4 months. For all planting dares, seasonal NIR (in) ranged between 8.46 to 9.36, 10.37 to 11.13, and 11.67 to 12.79 for 3, 3.5 and 4 months at Fortuna compared with 5.34 to 6.45, 6.36 to 7.40 and 7.51 to 8.80 for 3, 3.5 and 4 months af Isabela. In both locations minimum total NIR was observed in the November planting, whereas maximum total NIR was observed in the January planting. NIR was also estimated for a 20% rainfall probability which would represent dry years.Se estimó el requisito de riego neto (RRN) del sorgo para 5 épocas de siembra y 3 períodos distintos que terminaban a los 3, 3.5 y 4 meses. El estudio se hizo en las subestaciones agrícolas de Fortuna e Isabela, Puerto Rico. La subestación de Fortuna, Juana Díaz, está localizada en la costa semiárida del sur y la de Isabela en la costa húmeda del norte. Se utilizó el modelo modificado de Blaney-Criddle para estimar el uso consuntivo mensual a base de los promedios de temperatura y lluvia mensual. EL UC y RRN fueron mayores en la subestación de Fortuna para todas las fechas de siembra. En la siembra de enero, el RRN (pulg.) varió de 2.57 a 3.83, 0.71 a 3.83 y 2.13 a 4.24 para los períodos de 3, 3.5 y 4 meses en Fortuna, respectivamente, mientras que en Isabela los valores variaron de 1.53 a 2.76, 0.00 a 2.76 y 1.18 a 3.03 para los mismos períodos. El RRN (pulg.) total para Fortuna fue 9.36, 11.13 y 12.79 para los períodos de 3, 3.5 y 4 meses, respectivamente. Para estos mismos períodos en Isabela los valores fueron 6.45, 7.40 y 8.80, respectivamente. En ambos sitios el RRN mínimo ocurrió en marzo en el período de 3 meses y en abril para los períodos de 3.5 y 4 meses. En todas las fechas de siembra el RRN (pulg.) total varió de 8.46 a 9.36, de 10.37 a 11.13 y de 11.67 a 12.79 en Fortuna y de 5.34 a 6.45, de 6.36 a 7.40 y de 7.51 a 8.80 en Isabela, en los períodos de 3, 3.5 y 4 meses, respectivamente. En ambos sitios el RRN mínimo se observó en las siembras de noviembre, mientras que el RRN total máximo se observó en la siembra de enero. El RRN se estimó también para 20% de probabilidad de lluvia, lo cual representa un año seco

Genetic potential of tropically adapted exotic maize (Zea mays L.) heat-tolerant donor lines in sub-tropical breeding programs

Breeding for heat stress tolerance became a priority in sub-Saharan Africa (SSA), as projections are showing an increase in frequency, duration, and severity. In this study, 14 heat stress tolerant-donor lines (HSTDLs) sourced from CIMMYT-India (males) were crossed with 15 locally adapted elite lines (females) developed within the CIMMYT-Zimbabwe maize-breeding program using the North Carolina Design II mating scheme. The resultant 175 single crosses were evaluated alongside five commercial hybrids and adjacent to the trial of parental lines used in the crosses across two locations representing heat stress and optimal environments in Zimbabwe. The design II analysis showed significant (p < 0.01) general combining ability (GCA) effects for exotic heat donor lines and specific combining ability (SCA) effects on grain yield under heat stress, optimal conditions, and across locations; demonstrating additive and non-additive genetic inheritance of grain yield. High Baker’s ratios observed in this study indicate predominance of additive over non-additive gene effects. Three exotic HSTDLs, namely CAL14138, CAL152, and CAL1440, exhibited significant (p < 0.001) and positive GCA effects under heat stress conditions. The results imply that these exotic lines could serve as valuable genetic resources for introgression of heat tolerant alleles into local maize populations for accelerated yield genetic gains. Single crosses, DJ265-15 × VL1018816 and DJ267-9 × CAL1440, exhibited positive and significant (p < 0.01) and (p < 0.05) SCA effects for grain yield under heat stress conditions, respectively. These crosses can be used for further breeding and can contribute to grain yield performance under heat stress conditions. The exotic HSTDLs, CAL14138, CAL152, and VL109126 showed superior per se performance under heat, optimal conditions, and across environments. Overall data demonstrate the potential of exotic HSTDLs for improving the adaptation of maize to heat stress in sub-tropical breeding programs

Plant Phenotyping and Phenomics for Plant Breeding

As a consequence of the global climate change, both the reduction on yield potential and the available surface area of cultivated species will compromise the production of food needed for a constant growing population. There is consensus about the significant gap between world food consumption projected for the coming decades and the expected crop yield-improvements, which are estimated to be insufficient to meet the demand. The complexity of this scenario will challenge breeders to develop cultivars that are better adapted to adverse environmental conditions, therefore incorporating a new set of morpho-physiological and physico-chemical traits; a large number of these traits have been found to be linked to heat and drought tolerance. Currently, the only reasonable way to satisfy all these demands is through acquisition of high-dimensional phenotypic data (high-throughput phenotyping), allowing researchers with a holistic comprehension of plant responses, or ‘Phenomics’. Phenomics is still under development. This Research Topic aims to be a contribution to the progress of methodologies and analysis to help understand the performance of a genotype in a given environment

Modélisation spatialisée de la production des flux et des bilans de carbone et d'eau des cultures de blé à l'aide de données de télédétection : application au sud-ouest de la France

Les terres agricoles, qui occupent plus d'un tiers de la surface continentale de la Terre, contribuent au changement climatique et sont aussi affectées par ces changements puisque leur production est contrainte par les conditions climatiques et les ressources en eau. L'objectif principal de cette thèse est donc de quantifier et d'analyser la production et aussi les principales composantes des cycles biogéochimiques du carbone et de l'eau des agrosystèmes, pour des années climatiques contrastées, afin d'identifier les meilleures stratégies pour maintenir la production et réduire les impacts environnementaux. Ce travail a été focalisé sur les cultures de blé du sud-ouest de la France. Pour répondre à cet objectif nous proposons une approche de modélisation spatialisée qui combine : i) des données de télédétection optique à hautes résolutions spatiale et temporelle, ii) des modèles de culture semi-empiriques et iii) un ample dispositif de mesures in-situ pour la calibration et la validation des modèles. L'utilisation combinée de ces trois outils offre de nouvelles perspectives pour la modélisation et le suivi des agrosystèmes à l'échelle régionale et globale.The agricultural lands that occupy more than one third of Earth's terrestrial surface contribute to climate change and are also impacted by those changes, since their production is conditioned by climatic conditions and water resources. The main objective of this thesis is therefore to quantify and analyze the production and also the main components of the carbon and water biogeochemical cycles for crop ecosystems in contrasted climatic years, focusing specifically on the winter wheat crop, in order to identify the best strategies for maintaining crop production and reducing environmental impacts. The study area is located in southwest France. We propose a regional modeling approach that combines: i) high spatial and temporal resolutions optical remote sensing data, ii) simple crop models and iii) an extensive set of in-situ measurements for models' calibration and validation. The combined use of these three 'tools' opens new perspectives for advanced agro-ecosystems modeling and monitoring at regional or global scales

Physiological Mechanisms Underlying the High-Grain Yield and High-Nitrogen Use Efficiency of Elite Rice Varieties under a Low Rate of Nitrogen Application in China

Selecting rice varieties with a high nitrogen (N) use efficiency (NUE) is the best approach to reduce N fertilizer application in rice production and is one of the objectives of the Green Super Rice (GSR) Project in China. However, the performance of elite candidate GSR varieties under low N supply remains unclear. In the present study, differences in the grain yield and NUE of thirteen and fourteen candidate varieties with two controls were determined at a N rate of 100 kg ha-1 in field experiments in 2014 and 2015, respectively. The grain yield for all of the rice varieties ranged from 8.67 to 11.09 t ha-1, except for a japonica rice variety YG29, which had a grain yield of 6.42 t ha-1. HY549 and YY4949 produced the highest grain yield, reflecting a higher biomass production and harvest index in 2014 and 2015, respectively. Total N uptake at maturity (TNPM) ranged from 144 to 210 kg ha-1, while the nitrogen use efficiency for grain production (NUEg) ranged from 35.2 to 62.0 kg kg-1. Both TNPM and NUEg showed a significant quadratic correlation with grain yield, indicating that it is possible to obtain high grain yield and NUEg with the reduction of TNPM. The correlation between N-related parameters and yield-related traits suggests that promoting pre-heading growth could increase TNPM, while high biomass accumulation during the grain filling period and large panicles are important for a higher NUEg. In addition, there were significant and negative correlations between the NUEg and N concentrations in leaf, stem and grain tissues at maturity. Further improvements in NUEg require a reduction in the stem N concentration but not the leaf N concentration. The daily grain yield was the only parameter that significantly and positively correlated with both TNPM and NUEg. This study determined variations in the grain yield and NUE of elite candidate GSR rice varieties and provided plant traits that could be used as selection criteria in breeding N-efficient rice varieties

Título en español.

Differences in maturation time and daily grain yield were sought among cultivars and hybrids of sorghum (Sorghum bicolor (L.) Moench) grown in the tropics. Seven lines were used as males in crosses with three cytoplasmic-genetic male-sterile lines to produce 21 hybrids. Formation of the black layer (SL) was used as criterion for physiologic maturity. The male-parental lines and their hybrids were evaluated for grain yield/day from planting to midbfoom (GYMS), from planting to SL formation (GYSL), and from midbloom (MS) to SL formation (GYMS-SL), and for total grain yield at SL formation (GY). When results for the hybrids of each female line were averaged over the seven male-parental lines, hybrids of the female "Redlan' were first to reach MS and BL formation, and they produced the largest GYMS and GYSL. When results for the hybrids of each male-parental line were averaged over the three female lines, hybrids of the males 6, 9, and 10 were among the first to reach MS and SL formation, and were highest in GYMS, GYSL, GYMS-SL, and GY. For individual hybrids, differences in both maturation time and GY contributed to differences in daily grain yield, but the greater influence appeared to be that of GY. However, in five of the seven sets of hybrids having a given male parent (e.g ., A4, S4, and C4), the hybrid (with Redlan in each case) that was first to reach MS produced a GYMS equal to or higher than those of the hybrids that were slower to reach MS. Also in four of the seven sets of hybrids, the hybrid (with Redlan in three cases) that was first to reach SL formation had a GYSL higher than those of the later maturing hybrids. When the male-parental lines were selfed, lines 6, 9, and 10 produced the highest GY, GYMS, GYSL, and GYMS-SL. These lines were among the five earliest. In the tropics high yield/day and rapid maturation rate may be very desirable characteristics, and the current research identified hybrids with these characteristics. Redlan seems promising as a female parent for such desirable hybrids. Males 6, 9, and 10 seem promising as parent for GY, but they have some undesirable agronomic or quality characteristics.Siete líneas de sorgo de grano y sus híbridos (F1) fueron evaluados en la línea experimental del Instituto Mayagüezano de Agricultura Tropical. Tres líneas androestériles, CK-60, Martin y Redlan, se utilizaron como progenitores femeninos. La formación de "black layer" (BL) (tejido oscuro que se forma en la base de la semilla), se utilizó como índice de madurez fisiológica. La BL sirvió de ayuda en la búsqueda de diferencias en la producción de grano por día entre los siete padres e híbridos estudiados. Los progenitores masculinos y sus híbridos fueron evaluados en término de producción de grano por día desde la siembra hasta la mitad de la floración (GYMB), desde la siembra hasta la formación de BL (GYBL), desde la mitad de la floración (MB) hasta la formación de BL (GYMB-BL) y para la producción de grano a la formación de BL (GYBL). Los híbridos con el progenitor femenino androestéril Redlan, fueron los primeros en alcanzar la MB y la formación de la BL, y arrojaron los valores más elevados de GYMB y GYBL. Por otro lado, los híbridos con los progenitores masculinos 6, 9 y 10 fueron los primeros en alcanzar la MB y la formación de la BL. Además, estos arrojaron los valores más elevados en término de GYMB, GYBL, GYMB-BLy GY. Para los híbridos individuales, diferencias tanto en tiempo de madurez y GY contribuyeron a diferencias en producción de grano por día, pero la influencia mayor fue la de GY. Sin embargo, en cinco de los siete grupos de híbridos con un progenitor masculino dado (A4, B4, C4), el híbrido (con el progenitor femenino Redlan en cada caso), que fue el primero en alcanzar la MB produjo un GYMB igual o mayor que aquellos híbridos que fueron menos lentos en alcanzar la MB. En término de los progenitores masculinos, las líneas 6, 9 y lO arrojaron los valores más elevados de GY, GYMB, GYBL y GYMB-BL. Esas líneas estaban entre las cinco más precoces. En los trópicos, en donde se pueden lograr varias cosechas de una misma siembra, híbridos de sorgo o cultivares con un alto rendimiento por día deben ser los más deseables. Este estudio identifica híbridos con esas características