Effect of Gypsum and Drought on Pod Initiation and Crop Yield in Early Maturing Groundnut (Arachis hypogaea) Genotypes

Gypsum application and irrigation increased yield in early maturing groundnut genotypes in experiments using line source and conventional irrigation. Response to gypsum varied with genotype; with some gypsum increased yields at all water application rates, in some genotypes there was no response, while with others gypsum increased yield in drought conditions. In a separate study of the effect of gypsum and drought on pod initiation and development in three groundnut genotypes, gypsum did not greatly influence pod initiation when adequate irrigation was applied, but was beneficial when water was withheld during pod set and again during pod filling. Crops where the combination of gypsum and genotype were most advantageous in the first drought period subsequently grew more slowly so that there were no final differences in response to gypsum. Cultivar EC 76446(292) had a higher requirement for gypsum and was more susceptible to drought than the other two genotypes

Hydraulic Press Measurements of Leaf Water Potential in Groundnuts

The hydraulic press was compared with the dew point psychrometer and the pressure chamber methods for measuring leaf water potential (Ψ) in groundnuts (Arachis hypogaea L.). For measurements on the same leaf, regression analysis revealed that the slopes did not differ significantly from unity. An analysis of functional relations between measurements made by the press and the dew point psychrometer or the press and the pressure chamber showed that the error variance of the press was similar to those of the two other methods. Therefore, we conclude that for groundnuts the performance of the press, the dew point psychrometer and the pressure chamber are similar

Isolation of intact mesophyll cells from the leaves of higher plants

A total of 146 species of angiosperms belonging to 35 taxonomically diverse families were screened for the isolation of living mesophyll cells from the leaves. Seventy-three species belonging to 22 families, on mild maceration in mortar with the isolation medium (pH 5.8) containing 0.7 M mannitoJ, 2 mM EDTA, 5 mM MgCl2, 5 mM K2HPO4 and 1 mM NaNO3, followed by fractional centrifugation, yielded intact mesophyll cells as seen under a research microscope. The high frequency of cell release, associated with the high percentage recovery of chlorophyll in cells was a common feature of most of the plant species examined by us. Nearly 87% of the chlorophyll present in the leaf could be recovered from the isolated cells in Dolichos lablab. The isolated cells retained active photosynthetic carbon metabolism as evidenced by high rates of ferricyanide reduction as well as carbon assimilation

Differences in yield determining processes of groundnut (Arachis hypogaea L.) genotypes in varied drought environments

Thirty-six groundnut gentoypes of varied origin were evaluated for their yield, crop growth rates (C), and partitioning to reproductive sinks (p) in three trials. In the trials irrigation and sowing date were used to vary the amount of water available either throughout the crops' life, or through the grain filling phase. Genotype performance across the five environments for these attributes showed that although differences in C existed, differences in the stability of the partitioning were the dominant attribute of genotypes adapted to the drought prone Sahelian region. Data suggested that these differences were more attributable to tolerance to temperature and/or humidity than water stress. Over all treatments canopy temperatures relative to air (CATD) were strongly correlated with the C observed, but not so with yield; and differences between genotypes in the relationship between C and CATD were not statistically significant

Within-individual phenotypic plasticity in flowers fosters pollination niche shift

Authors thank Raquel Sánchez, Angel Caravante, Isabel Sánchez Almazo, Tatiana López Pérez, Samuel Cantarero, María José Jorquera and Germán Fernández for helping us during several phases of the study and Iván Rodríguez Arós for drawing the insect silhouettes. This research is supported by grants from the Spanish Ministry of Science, Innovation and Universities (CGL2015-71634-P, CGL2015-63827-P, CGL2017-86626-C2-1-P, CGL2017- 86626-C2-2-P, UNGR15-CE-3315, including EU FEDER funds), Junta de Andalucía (P18- FR-3641), Xunta de Galicia (CITACA), BBVA Foundation (PR17_ECO_0021), and a contract grant to C.A. from the former Spanish Ministry of Economy and Competitiveness (RYC-2012-12277). This is a contribution to the Research Unit Modeling Nature, funded by the Consejería de Economía, Conocimiento, Empresas y Universidad, and European Regional Development Fund (ERDF), reference SOMM17/6109/UGR.Phenotypic plasticity, the ability of a genotype of producing different phenotypes when exposed to different environments, may impact ecological interactions. We study here how within-individual plasticity in Moricandia arvensis flowers modifies its pollination niche. During spring, this plant produces large, cross-shaped, UV-reflecting lilac flowers attracting mostly long-tongued large bees. However, unlike most co-occurring species, M. arvensis keeps flowering during the hot, dry summer due to its plasticity in key vegetative traits. Changes in temperature and photoperiod in summer trigger changes in gene expression and the production of small, rounded, UV-absorbing white flowers that attract a different assemblage of generalist pollinators. This shift in pollination niche potentially allows successful reproduction in harsh conditions, facilitating M. arvensis to face anthropogenic perturbations and climate change. Floral phenotypes impact interactions between plants and pollinators. Here, the authors show that Moricandia arvensis displays discrete seasonal plasticity in floral phenotype, with large, lilac flowers attracting long-tongued bees in spring and small, rounded, white flowers attracting generalist pollinators in summer.Spanish Ministry of Science, Innovation and Universities (EU FEDER funds) CGL2015-71634-P CGL2015-63827-P CGL2017-86626-C2-1-P CGL2017-86626-C2-2-P UNGR15-CE-3315Junta de Andalucia P18-FR-3641Xunta de GaliciaBBVA Foundation PR17_ECO_0021Spanish Ministry of Economy and Competitiveness RYC-2012-12277Consejeria de Economia, Conocimiento, Empresas y Universidad SOMM17/6109/UGREuropean Union (EU) SOMM17/6109/UG

Semi-arid Crop Responses to Atmospheric Elevated CO2

Invited Mini-Review: Semi-arid tropics host most of the poor and small-holding farmers of the developing world. Global warming is seen largely as a consequence of continuous increase in the emission of carbon dioxide and other greenhouse gases into the atmosphere leading to unusual changes in global temperatures and rainfall patterns. This in turn is expected to increase the water scarcity in the environment, affecting plant growth and metabolism. In this context, we reviewed semi-arid crop responses to elevated CO2 levels in terms of growth, yield components, physiological, biochemical and molecular changes. Predicted rise of carbon-dioxide in the atmosphere may benefit the plants by increasing the crop water use efficiency and net photosynthesis leading to greater biomass, yield and harvest index. C3 and C4 crop plants vary in their degree of response to elevated CO2, which will likely affect the proportion of land area occupied by these crops in future. Stomatal conductance will probably be reduced at higher CO2 concentrations reducing transpiration per unit leaf area and consequently increasing the leaf temperature. The high CO2 is an ameliorative of the adverse effects of drought and acts by altering the plant, biochemical and molecular systems. Understanding of the direct effects of elevated CO2 and its interactions with the other climate variables is needed in order to predict the impact of climate change scenarios on crop growth and food security in future

Correlation between the rates of foliar dark respiration and net photosynthesis in some tropical dicot weeds

The rates of foliar dark respiration and net photosynthesis in attached leaves of 25 C3, C4, and C3-C4 intermediate dicotyledonous weed species were determined using the infrared gas analyzer. The ratio of dark respiration to photosynthesis per unit leaf area in attached leaves of each species was inversely proportional to leaf age. Highly significant, positive linear correlation was observed between the rates of foliar dark respiration and net photosynthetic CO2 uptake in dicot weeds irrespective of the photosynthetic type. The higher foliar dark respiration rate found in some of the weed species can be attributed in part to the higher carbohydrate levels as generated by a rapid photosynthetic CO2 assimilation. The significance of higher dark respiration rate in relation to carbon and energy economy of weeds is discussed