-->Physiology

Effects of different intensities of red or blue on chlorophyll fluorescence characteristics of bean leaves

2015/12/14 17:02:55

Common bean is widely planted all over the world with a wide variety of ecological conditions. The photosynthesis of bean leaves varies remarkably under different ecological conditions which may be correlated to differing light quality and the light intensity. In order to study the effects of different intensities and qualities of the light on the photosynthesis of plant,bean(Phaseolus vulgaris)leaves were used as the material,and Pulse-Amplitude-Modulation chlorophyll fluorometer was used to record the changes of the chlorophyll fluorescence parameters with different light intensities of red or blue,primary leaves were offered to the treatments in the present work. The results showed that the maximum photochemical efficiency of light adaptation(F_v'/F_m',the efficiency of capture excitation energy in PSⅡ reaction center )decreased with the increase of light intensities of red or blue light,but the values of F_v'/F_m' under blue light were significantly(P<0.05)or very significantly(P<0.01)higher than those under the same intensities of red light. With the increase of light intensities of blue light,the actual photochemical efficiency of PS Ⅱ(Y(Ⅱ),the actual photochemical efficiency of PS Ⅱ under light)and the coefficient of photochemical fluorescence quenching(qP and qL,the proportion of reduction state of PS Ⅱ original electron acceptor-plastoquinone(Q_A)increased but became stable gradually,while the values of Y(Ⅱ),qP and qL decreased with the increase of red light intensities. These meant that the photosynthetic efficiency of bean leaves decreased with the increase of blue or red light intensities. Non-photochemical quenching coefficient(NPQ,the excess energy dissipation by PS Ⅱ antenna system),electronic transmission rate(ETR,ETR increases linearly with light intensity,until it reaches a maximum. This happens when the capacity of all electron sink is reached),and quantum yield of regulated energy dissipation[Y(NPQ),an important indicator of self protection and the ability of PS Ⅱ to deal with excess light energy] increased with the increase of blue light or red light intensity. Compared to under red light,the values of ETR under blue light were higher but the values of NPQ and Y(NPQ) were lower. Quantum yield of non-regulated energy dissipation[Y(NO),the proportion of excess light energy in the form of heat and fluorescence,one of the important indicators of light damage] increased with the increase of red light intensity but decreased with the increase of blue light intensity. These results showed that the photosynthetic efficiency of bean leaves decreased with the increase of light intensities,but the absorbing and utilizing efficiencies of blue light were higher than those of red lights. We believe that this work would be helpful in developing current understanding on the responses of plants to different light intensities and qualities.

Effects of salicylic acid on cold resistence of Paeonia suffruticosa leaves

QIAO Yong-Xu — 2015/12/14 17:02:56

In order to explore the physiological mechanism of salicylic acid(SA)improving ability against chilling injury of plant leaves,20 d old leaves of Paeonia suffruticosa cultivar ‘huhong' were treated by 0,0.5,1.0,1.5 and 2.0 mmol·L^-1 SA under 4 ℃ darkness incubator,and then effects of SA on the contents of H₂O₂,O^-₂·,soluble sugar,soluble protein and malonaldegyde(MDA)content,the activities of guaiacol-dependent peroxidase(POD),superoxide dismutase(SOD)and catalase(CAT),and membrane permeability in leaves of P. suffruticosa were investigated in 0,4,8,12 h later. The results showed that low concentration of SA(<2.0 mmol·L^-1)could reduce chilling injury of leaves of P. suffruticosa,the content of H₂O₂,O^-₂· and MDA,and membrane permeability of leaves of P. suffruticosa. However,it could increase the contents of soluble sugar and soluble protein,and activities of POD,SOD and CAT of leaves of P. suffruticosa. Especially,1.0 mmol·L^-1 SA could decrease contents of O^-₂· and MDA,and reduced chilling injury of leaves of P. suffruticosa. The longer the time of lower temperature treatment was,the stronger the protection of SA to leaves of P. suffruticosa was 2 mmol L^-1 SA did not significantly reduce the low temperature inducing leaf water salinization degree. The degree of chilling injury of leaves P. suffruticosa under 4 ℃ for 12 h whether to 2 mmol L^-1 SA use or not was the same. It was concluded that whether SA can obviously improve ability against chilling injury of leaves P. suffruticosa depended on SA concentration. 1.0 mmol·L^-1 SA reduced chilling injury of leaves of P. suffruticosa,while the lower or higher concentration SA could not obviously increase the cold resistance of leaves of P. suffruticosa. The results can be applied quickly in early spring production of P. suffruticosa,and provide the theoretical reference for ability against chilling injury of other crops.

Dynamic analysis for glucose mobilization and hydrolytic enzyme activity at different germination stages in sweet corn

CHENG Xin-Xin, LIU Yan-Long, NIU Yong-Sheng, LIU Zheng — 2015/12/14 17:02:56

Seed germination is a complex physiological and biochemical process that the storage material is broken into sucrose,glucose and other sugars compounds under the action of enzyme reaction in order to provide the carbon source and energy for seedling growth. In this study,the dynamics of storage carbohydrate mobilization,sucrose synthase activity and amylase were analyzed at different seed germination stages by using two different seeds that the grain nutrients are different are from different countries in sweet corn. The results showed that there were significant differences for storage carbohydrate mobilization between E22 and T26 including the mobilized seed reserve,seed reserve utilization,sucrose,glucose and fructose content. Starch is the key factor of seed germination in sweet corn because of the outstanding material utilization in T26. By comparison,the mobilized seed reserve in T26 was lower,while the seed reserve utilization efficiency was higher. During seed germination,sucrose and glucose contents were higher for E22 in 4-8 d and 6-10 d,while fructose content was higher for T26 in 10 d. Amylases and sucrose synthase activities were increased durining the process of seed germination. Grey correlation analysis showed that the mobilized seed reserve was affected by the amylases during seed germination and seed reserve utilization was constrained by sucrose content,glucose content and fructose content. Improving of seed reserve utilization in sweet corn is of great significance to strengthen the seed germination and seedling growth,to enhance its competitiveness with weeds and to increase production.

Effects of the changes in the contents of K, Ca and Mg in pericarp on the pericarp's coloring of Litchi chinensis cv. Ziniangxi

2015/12/14 17:02:57

In order to study the characteristics of the changes in the contents of K,Ca and Mg in pericarp and its effects on the pericarp's coloring of Ziniangxi litich,a study based on the pericarp was finished. The characteristics of the tendencies of the changes in the contents of K,Ca and Mg and the indicators of coloring in pericarp were detected,and the relationship between the changes in the contents of 3 kinds of mineral nutrients and the pericarp's reddening were analyzed by the methods of the canonical correlation analysis and the unitary exponential regression analysis. The results in the course of the development of the pericarp's reddening were as follows: The content of chlorophyll in pericarp decreased significantly while the content of anthocyanin in pericarp increased significantly. The contents of the total K,the water-soluble K and the total Ca,the water-soluble Ca generally dropped and rose respectively. The content of the water-soluble Mg generally rose. The content of the total Mg changed insignificantly. The contents of the total K,Ca and Mg and those of the water-soluble K,Mg and Ca respectively decreased significantly in sequence at the same time. The unitary exponential regression equations of the content of the anthocyanin to those of the total Ca and K respectively were both significant,and the correlation was respectively positive and negative. The unitary exponential regression equations of the content of the chlorophyll to those of the water-soluble Mg and the total Ca and K were all significant respectively,meanwhile,the former two were both negative,and the latter was positive. In summary,the higher content of the total Ca was the key factor improving the pericarp's reddening,and it would guide to formulate the technical proposals on the fertilizer application for improving the pericarp's reddening of Ziniangxi litchi.

Responses of Lactuca sativa and Festuca arundinacea to the allelopathy of water extracts from Jacaranda mimosifolia flowers

2015/12/14 17:02:58

In order to verify whether there are relevant substances in Jacaranda mimosifolia that can produce the allelopathy to other plants. We studied the allelopathy of the concentration of 0.001,0.025,0.050 g·mL^-1 water extract of the flowers of J. mimosifolia for the seed germination and seedling growth, taking the complete single flowers of J. mimosifolia grown in Wenjiang region as materials,the seeds of Lactuca sativa and Festuca arundinacea as receptor materials, and the water treatment as the control CK. The results were as follows: firstly,the seed germination of F. arundinacea and Lactuca sativa was suppressed by the water extract,especially performance on the germination index, and the comprehensive allelopathies(SE2)were -0.13 and -0.27 respectively; secondly,the seedling height of L. sativa was promoted but its root length and root-shoot ratio were suppressed,and the values of SE3,SE₄,SE5 were 0.13,-0.36,-0.16, while the root-shoot ratio of Festuca arundinacea were promoted but its seedling height and root length were suppressed,and the values of SE3,SE4,SE5 were -0.12,-0.08,0.16 respectively. Meanwhile the MDA contents and root vigor of Lactuca sativa were also suppressed,whose values of SE6 and SE7 were -0.25 and -0.44,the values of Festuca arundinacea were 0.04 and 0.34 reversely. Most of all, when the concentration of the water extracts was 0.025 g·mL^-1, it showed the RI peak and inflection point of some trend in many places, especially the changes in MDA contents and root vigor of receiver plant's leaves. Thus, the experiment proved the existence of allelochemicals in water extract of Jacaranda mimosifolia flowers, Lactuca sativa and Festuca arundinacea,and they had different responses to the allelochemicals,which will provide the relevant theoretical basis to the plant landscape design and maintenance of Jacaranda mimosifolia in the future.

Physiological characteristics of the halophytic plant Kalidium foliatum to salt stress

2015/12/14 17:02:59

At present, more and more serious soil salinization is one of the main environmental factors that limit plant growth and crop yield. Many halophilous plants often grow in the saline-alkaline land. In order to better understand the salt tolerant mechanism of halophytic plants,this paper mainly explored some physiological characteristics of the halophytic plant Kalidium foliatum to salt stress according to some physiological indexes. The halophyte K. foliatum is a kind of very salt-tolerant shrub belonging to Chenopodiaceae with high succulence and grows commonly in saline and alkaline arid-desert regions in Xinjiang. Some physiological parameters were detected including the contents of Na⁺,K⁺,Ca²⁺ and proline,the water potential of plant leaf tissue, the content of membrane lipid peroxidation(MDA)and phenotype observation; gene expression of KfP5CS,encoding protein(pyrroline-5-carboxylate synthetase)as a key enzyme catalyzing to synthesize proline by semi-quantitative RT-PCR were assayed to salt stress. The results were as follows:(1)Na⁺ could accumulate significantly in succulent leaves and roots of K. foliatum,and even the content of Na⁺in leaves was more than roots;(2)With increasing salt concentration,the content of proline and the gene expression of KfP5CS were enhanced significantly under salt stress conditions;(3)Na⁺ and proline as plant effective osmotic regulators, could make the plant cells be still able to absorb water at low water potential from the highly concentrated salt solution,extracellularly;(4)Under 0 and 700 mmol·L^-1NaCl treatments, the contents of MDA in the leaves of K. foliatum were higher than other salt treatments, suggesting that the plants might be subjected to oxidative stress under the both treatments. This phenomenon indicated that the growth environments with the both treatments might be adverse for the plants;(5)From the growth phenotype to salt stress, the biomass of K. foliatum was more under low salt treatments, and the plant growth was better and stronger, indicating the low salt environment seemed to be beneficial to the K. foliatum growth. In summary, the results of the investigation of the K. foliatum plant growth in wild grown environment and under long-term salt stress in our lab showed that it was necessary for the good growth of K. foliatum in a certain salt concentration condition. A relative low salt concentration environment is very optimal for the growth of some very salt-tolerant halophytes like K. foliatum. However, we can also speculate neither salt nor high concentration salt conditions is the stressed environment for the K. foliatum plant growth. The study could provide primary reference for understanding the salt tolerance of K. foliatum and it is also very promising to improve salt tolerance in crops and woods by making use of gene resources of this species and the halophyte K. foliatum could be also used to ameliorate saline-alkaline land by reducing the salt content of soil.