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ya gal actually let the house !! it's a revelation !! also my best friend in the entire world has come home im the happiest little thing in the world right now ☺️🌻💛✨

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Morpho-agronomical and physiological response of cotton seedlings to low nitrogen supply

Abstract

Among the crop production factors, nitrogen is the most important limiting factor of crop production. The relationship between photosynthesis and nitrogen nutrition has been widely studied in different crops. However, in cotton leaf photosynthetic traits and nitrogen use efficiency are less clear at the seedling stage. It was found that low nitrogen supply significantly reduced cotton growth, photosynthesis, nitrogen content and ultimately the nitrogen use efficiency except root morphological traits. Correspondingly, all the parameters related to gaseous exchange were very sensitive to nitrogen deficiency and therefore reduced. However, the intercellular CO2 concentration and nitrogen efficiency ratio were increased under low N supply. These results suggest the possibility of utilizing these traits as indicators for optimum nitrogen fertilization and development of nitrogen efficient genotypes. Further, this could lead to the development of sustainable agriculture for better crop productivity and profitability as well as environmental protection.

Introduction

Nitrogen (N) availability is one of the most important factors limiting plant growth and productivity in both natural and agricultural environments. It is an essential input in agricultural production and is the main constituent of many macromolecules, secondary metabolites and signaling compounds, which are required for plant growth and development. N fertilizer applications have previously provided an important guarantee for increasing food, feed and fiber production and reducing the pressure of global population growth. However, sub-optimal N supply is a major constraint for crop production, causing up to 50% yield loss (Jones et al., 2013; Iqbal et al., 2015). For this reason, large amounts of N fertilizer are applied to improve plant growth and yield (Glass, 2003; Sarasketa et al., 2014) with an expected threefold increase in application rate in the future (Good et al., 2004). Indeed, large production and consumption of N fertilizer (amount to 30% of worldwide levels) in China have made a significant contribution to Chinese agricultural development (Zhang et al., 2013). However, excess N fertilizer applications for crop production exert adverse environmental impacts, resulting in higher N2O emissions and the eutrophication of freshwater and marine ecosystems (Qiao et al., 2012). Over application of nitrogen has been a common problem in China, resulting in low N use efficiency (NUE) and environmental pollution (Miao et al., 2011).

Beside the over use, nitrogen deficiency has also negative impacts like reducing plant growth and development, photosynthesis, leaf area, and ultimately limits plant productivity (Chen et al., 2016). For a sustainable crop production system, there is a requirement to properly manage nitrogen fertilizer input and increase nitrogen use efficiency. This may be achieved by understanding the relationship between N nutrition and the photosynthetic rate in the leaf (Mu et al., 2016). Photosynthesis depends on many physiological and biochemical processes such as stomatal conductance, intercellular CO2 concentration, photochemical capacity of PSII, and contents and activities of carbon fixation enzymes (Zhao et al., 2005). Photosynthesis has a positive relationship with leaf nitrogen (Uribelarrea et al., 2009). This is because about 70% of leaf nitrogen is located in the chloroplast (Ghannoum et al., 2005). Nitrogen deficiency reduces the content of chlorophyll, Cyt f, coupling factor, N content of thylakoid in light reactions, as well as the electron transport chain (Mu et al., 2016). The decreased photosynthesis in low nitrogen was mainly associated with lower stomatal conductance (Zhao et al., 2005). Therefore, combination of photosynthesis and related parameters are very important to know the crop productivity and finally the nitrogen use efficiency (NUE). Clearly, NUE is a complex trait that must be encoded by many different genes and their environmental interactions, but it can be dissected into two components. Firstly, the ability of the plant to take up N from the soil termed “nitrogen uptake efficiency” and secondly the ability of the plant to transfer N to plant organs and yield, known as “nitrogen utilization efficiency” (Xu et al., 2011). Several studies on model and crop species have highlighted the genetic variability and the complex regulatory mechanisms controlling NUE under low and high N supply (Krapp et al., 2011). Given the importance of the topic, it is surprising that relatively few papers have compared measures of NUE for cotton growing in different environments. However, it can be improved by precision nitrogen management and nitrogen efficient genotypes. For both approaches, it is necessary to diagnose plant nitrogen nutrition status timely and precisely. The importance of optimizing N management together with the selection of efficient genotypes may decrease excess fertilizer applications (Good and Beatty, 2011) which will subsequently reduce nitrogen leaching and environmental damage (Good et al., 2004; Sebilo et al., 2013).

Cotton (Gossypium L.) known as the white gold is the backbone of textile natural fiber in the world, grown worldwide in more than 50 countries (Smith and Cothren, 1999). Among the production inputs, nitrogen has the most vital role in cotton. Nitrogen is an essential element for canopy area development and photosynthesis (Wadleigh, 1944). Providing the right N amount during the plant growth will provide healthy leaves with the photosynthetic capacity needed to support the growth of the reproductive components (Bondada and Oosterhuis, 2001). Therefore, like other crops, cotton also increase the root morphological traits as well as reduces their N assimilation activities in response to low nitrogen supply, so that to adapt to the low nitrogen condition with the allocation of N resources to the leaves, which enhance the photosynthetic rates (Li et al., 2012). Although the relationship between nitrogen deficiency and photosynthesis has been widely studied in other crops, less is known about the response of the photosynthetic system and nitrogen use efficiency in cotton to low nitrogen supply. However, the response may be different depending on the genotypes and species, leading to variations in their growth characteristics, adaptability to the environment, and morphological traits. Cotton morphological and physiological responses to low nitrogen have not yet been investigated, and the use of these traits in breeding programs requires the preliminary characterization. Such information is important not only for improving photosynthesis and nitrogen use efficiency performance under low nitrogen supply but also for the development of potential tools for the diagnosis of plant nitrogen nutrition status. This could be used in both the selection of nitrogen-efficient genotypes and precision nitrogen fertilizer management. Therefore, our study aims at characterizing the performance of cotton morpho-physiological analysis along with nitrogen use efficiency at seedling stage in response to low nitrogen supply.

Source : Morpho-agronomical and physiological response of cotton seedlings to low nitrogen supply

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Blurry pic but had such a nice day w my boo. Watched black panther, smoked a j, had beer at the theatre!!(didn’t know this was a thing) and then bought colour your own weed stickers that we both filled out. Then on top of it the moon was HUGE and beautiful as always. So I just feel happy n at peace for once n wanted to document it 😛