Causes And Consequences Of Variation In Growth Rate And Productivity Of Higher Plants Pdf
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- Plant morphology
- Environmental Factors Affecting Plant Growth
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This resulted in a reduction in gas exchange parameters and a subsequent decrease in growth variables and nutrient uptake, whereas these parameters increased significantly with increasing K levels.
Moreover, in principal components analysis, these variations were highly clustered under nitrate nutrition and highly separated under ammonium nutrition. Our study shows a clear positive interaction between K and N, suggesting that high K supply relieves ammonium stress while improving growth vigor under nitrate nutrition by enhancing nutrient uptake and assimilate production in wheat plants.
Nitrogen N is a key element required for plant growth, and is one of the most important yield-limiting nutrients in crop production in all agro-ecological regions of the world. Different N forms can affect the physiological and metabolic processes of plants, such as nutrient uptake, enzyme activity, photosynthesis rate, respiration rate, water balance, and signaling pathways, thus eventually influencing plant growth and crop yield 3 , 4 , 5 , 6. K, which is an essential nutrient involved in many important plant physiological processes, can improve crop yield and quality and enhance stress tolerance 23 , Thus, N and K requirements and management of these essential nutrients for crop production have become a focus of research into the interactions between N and K in terms of factors such as form and rate.
Currently, the imbalanced fertilizer use is common in field production in many developing countries. The practice often leads to an excess of soil N combined with a serious and continual depletion of soil K, mainly due to the application of excessive N and inadequate K Over-application of N is a serious problem in intensive agricultural production areas because this leads to enrichment of reactive N constituents in the environmental, soil acidification and also affects the transformation of soil N forms, with consequent impairment of ecosystems 26 , 27 , Thus, we hypothesized that plant growth and crop yield are influenced not only by the amount of available N in the soil, but also by the N forms, and that the process can be regulated by K supply.
Although the individual effects of different N forms on plant growth have been widely studied, the combined effects of various levels of N forms and K supply on wheat growth and crop yield are largely unknown. Similarly, little is known about the effects of K supply relative to N forms on the photosynthetic process and nutrient uptake in wheat plants.
In this study, we investigated the effects of different levels of N forms and K supply on growth in wheat plants, primarily by investigating biomass, growth, gas exchange, and N and K uptake.
These results were also clearly supported by the images collected during the culture stage Fig. Regardless of the N form, the high N rate significantly decreased the root:shoot ratios. A clear positive interaction was observed among N forms and rates and K levels on the biomass of the different organs except the panicle; however, there were no significant differences in the root:shoot ratios among the different K levels.
Effects of different levels of N forms and K supply on the plant growth in wheat seedlings. The P n , g s , and T r values increased significantly with the K levels, while C i decreased.
Independent of K levels, the N concentration of different organs including root, stem, leaf, and panicle were regulated by both N form and rate Fig. Regardless of N forms and rates, the organ K concentrations increased with K levels Fig. Effects of different levels of N forms and K supply on the N a — d and K e — h concentrations in wheat roots, stems, leaves, and panicles. NS, no significant difference. Effects of different levels of N forms and K supply on the N a — d and K e — h accumulations in wheat roots, stems, leaves, and panicles.
The accumulation of N and K was similar to pattern of changes in the K concentration Fig. The results showed that the growth and physiological parameters were significantly separated under the different N forms, with the first two principal components accounting for Principal component analysis PCA of ammonium a , nitrate b , and ammonium plus nitrate c based on growth and physiological parameters under different N rate with K supply treatments.
As shown in Fig. Data represent the mean of five replications. Plant growth is clearly affected by the forms of N supplied as nutrient. In accordance with this, Huang et al. Furthermore, Wang et al.
In contrast to these findings, Walch-Liu et al. Moreover, the effect of N forms on root:shoot ratios is mediated by regulation of the N rate. Lu et al. Zhou et al. However, dynamic changes in root:shoot ratios at various sampling points have also been observed in wheat 35 and sugar beet These results indicate that the effects of N forms on root and shoot growth in different species and at different N rates and sample points are mediated primarily by altering the partitioning of fixed carbon C during photosynthesis in both root and shoot.
These results was consistent with those reported by Guo et al. However, differences in biomass production, gas exchange, root and leaf morphological and physiology observed under conditions of different N forms 5 , 6 , 21 , 40 , 41 , 44 , indicate that the N forms available affect plant growth and photosynthesis. N form and rate affect plant growth by regulating photosynthetic carbon fixation and distribution as well as plant nutrient uptake.
These findings further indicated the influence of N uptake and assimilation on the responses of plants to N forms and rates in C fixation or biomass production. In addition, Guo et al. Walch-Liu et al. Thus, we suggest that plant K uptake may be influenced not only by the amount of available N in the environment, but also by the N forms. Our studies in wheat showed that N forms affect plant growth and the uptake of N and K nutrients; however, the supply level of K also has a significant influence on the regulation of plant growth, photosynthesis and nutrient absorption, with a positive interaction identified between N and K.
This is consistent with the proposed theory that cycling of K in plants can act as an important signal for feedback control of nutrient uptake K is an essential macro-element of nutrition in plants and its uptake is strongly influenced by other elements, such as N.
Based on the proposals of Szczerba et al. These results provide evidence that assimilate partitioning in plants can be improved by changes in K supply.
Some studies suggest that the controversial effects of N forms and K supply on plant growth are related to the availability of photo-assimilates for production, transportation and distribution, further indicating that K plays an important role in yield formation 23 , 47 , However, Zaman et al. Kong et al. It has also been reported that the consequences of N metabolism 55 , N use efficiency 48 and C-N balance 56 are improved by K fertilizer application. Similarly, the results of the present study suggest that a positive synergistic interaction between K and N on assimilate production, nutrient uptake, yield formation and stress tolerance 47 , Our results provide the basis for the development of new nitrogen fertilizer utilization schemes for wetland wheat production.
A split-unit randomized complete block design, with N forms as the main unit and factorial combinations of N rates and K levels as subunits, was used in this study. When the seedlings had an average of 2. Seedlings were grown in a greenhouse under a natural photoperiod. Four days later, the seedlings were transferred to half-strength nutrient solution. After an additional four days, the seedlings were treated with full-strength nutrient solution containing 12 different treatments AN2K0.
Nutrient solutions were changed every 4 d, after drip washing the sand surface with 0. Each treatment group consisted of six plants in a completely randomized design to minimize edge effects. Each treatment group consisted of three plants and was replicated three times in a completely randomized design.
At the heading stage, 60 days after treatments initiation, the light-saturated photosynthetic rates of newly expanded leaves flag leaf were measured simultaneously between and with an infrared gas analyzer XT, Li-Cor, Lincoln, NE, USA.
Data were recorded after equilibration to a steady state. The chlorophyll index was determined as the mean of six SPAD readings from the same leaf at the heading stage.
Wheat plants were harvested and separated into root, stem including sheath and culm , leaf and panicle sections. Sand was washed from the roots before the root volume was measured using the displacement method described by Sattelmacher et al. The leaf area was determined using a photocopy of the leaf and calculated according to the paper area.
The specific leaf weight was then calculated as the ratio of leaf weight to leaf area. The measurements were validated using certified standard reference materials obtained from the Institute for Environmental Reference Materials of the Ministry of Environmental Protection Beijing, China. Samples were analyzed in triplicate and mean values were used in comparisons analysis.
Britto, D. USA 98 , — Glass, A. The regulation of nitrate and ammonium transport systems in plants. Guo, S. Effect of ammonium and nitrate nutrition on some physiological processes in higher plants - growth, photosynthesis, photorespiration, and water relations. Plant Biol. Szczerba, M. Yang, X. Drought-induced root aerenchyma formation restricts water uptake in rice seedlings supplied with nitrate. Plant Cell Physiol. Ding, L. The enhanced drought tolerance of rice plants under ammonium is related to aquaporin AQP.
Plant Sci. Kronzucker, H. Ammonium toxicity and the real cost of transport. Trends Plant Sci. Plant Physiol. Physiological and biochemical processes related to ammonium toxicity in higher plants.
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Tipburn, a leaf marginal apex necrosis, is a serious problem in vegetable production under controlled environments Cox et al. Tipburn is generally considered a calcium-associated physiological disorder Bangerth, ; Thibodeau and Minotti, The necrosis results from the rupturing of laticifer cells Olson et al. Many researchers have reported that tipburn is associated with rapid growth rate and high calcium demand in leaves Collier and Tibbitts, ; Gaudreau et al. The rate of plant growth can be increased by controlling the cultivation environment, and light intensity is an important environmental factor in such stimulation. In a plant factory, which is a closed system equipped with artificial light and a controlled environment system to produce high-quality crops all year-round Kozai, ; Kozai et al.
D. Consequences of a High Growth Potential for Plant Performance in mechanisms which cause variation in any of these traits. We will treat the Rate and Productivity of Higher Plants (Ed. by H. Lambers, M.L. Cambridge.
Phytomorphology is the study of the physical form and external structure of plants. Recent studies in molecular biology started to investigate the molecular processes involved in determining the conservation and diversification of plant morphologies. In these studies transcriptome conservation patterns were found to mark crucial ontogenetic transitions during the plant life cycle which may result in evolutionary constraints limiting diversification.
The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of climate change on community composition change within a relatively short period several decades based on long-term monitoring data from two plots—Dinghushan Biosphere Reserve, China DBR and Barro Colorado Island, Panama BCI —that are located in tropical and subtropical regions. The results indicated that the population growth rate of a majority of populations has decreased over the past few decades.
Plant growth and geographic distribution are greatly affected by the environment. For example, only plants adapted to limited amounts of water can live in deserts. Either directly or indirectly, most plant problems are caused by environmental stress. In some cases, poor environmental conditions e. In other cases, environmental stress weakens a plant and makes it more susceptible to disease or insect attack.
Environmental Factors Affecting Plant Growth
Plant species from unproductive or adverse habitats are often characterized by a low potential relative growth rate RGR. Although it is generally assumed that this is the result of selection for specific trait combinations that are associated with a low rate of net biomass accumulation, few studies have directly investigated the selective dis- advantage of specific growth parameters under a set of different environmental conditions. Aim of the present study was to quantify the impact of inherent differences in growth parameters among phenotypes of a single plant species, Lychnis flos-cuculi , on their performance under different soil nutrient conditions. Growth analysis revealed significant variation in RGR among progeny families from a diallel cross between eight genotypes originating from a single population. A genetic trade-off was observed between these two components of growth, i. The degree of plasticity in RGR to nutrient conditions did not differ among progeny families.
Мы должны немедленно вырубить электроснабжение. Немедленно. Казалось, на директора его слова не произвели впечатления. - Должен быть другой выход. - Да, - в сердцах бросил Джабба. - Шифр-убийца.
Original Research ARTICLE
Сьюзан сладко потянулась и взялась за. Она загрузила программу Следопыт и, приготовившись отправиться на охоту, взглянула на адрес электронной почты, который вручил ей Стратмор. NDAKOTAARA. ANON. ORG У человека, назвавшегося Северной Дакотой, анонимные учетные данные, но Сьюзан знала, что это ненадолго.
Бринкерхофф обнимал Мидж. Соши заливалась слезами. - Джабба, - спросил Фонтейн, - много они похитили. - Совсем мало, - сказал Джабба, посмотрев на монитор. - Всего лишь какие-то обрывки, в полном виде - .
Не сбиваясь с курса. Именно эта целеустремленность всегда изумляла, эта неколебимая верность принципам, стране, идеалам. Что бы ни случилось, коммандер Тревор Стратмор всегда будет надежным ориентиром в мире немыслимых решений. - Так ты со мной, Сьюзан? - спросил .
Все тихо и чисто. Перед сердечным приступом мистер Танкадо не почувствовал ничего, кроме легкого укола.