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Abstract - 162 - SUI.tLtARY The :present investigation was carried out aiming to study th~ halophytic features of barley plants (Sahrawy cultivar) grovmunder different salinity levels. Some biuchemiQal measurements representing by the analysis of crude protein, total carbohydrates, amino acids and mineral contents in shoots and grains were taken as indications for the $daptabil~ty of such pla~t species. Besides, complementary ~nformations on growth and yield characters were tested t$ evaluate the relevance of the biochenical measurments to pla~t adaptation. On the other direction, the corrective influence of some cytokinins and growth retardants on growth, yield and metabolism were also tested under different levels of salinity. Two pot-experiments were conducted during 1978/79 and 1979/80 seasons under green-house conditions. Seeds were sovm in November, 15 for both seasons in glazed porcelain pots filled with 25 Kg sandy soil of EI-Tahrir Province. Thinning was performed 44 days from sovdng leaving 20 plants per pot. The cytokinins used were kinetin and benzimidazole whereas the growth retardants were Alar and Phosphone. Such growth regulators were applied twice as foliar spray 20 and 44 days fram sovnng in the levels: 20, 10, 500, 500 ppm, respeotively. - 16) - Four HaCl salinity treatments, in addition to control (tap water), were used namely: 6000, 8000, 10000,and 12000 ppm. Salinity treatments were applied 34 days after so,nng. The treatment conditions were arranged in randomized block desingn with 5 replications. Combined fertilizer (NPK) was applied together with the first irrigation of saline water 34 days from sovdng. For both seasons, three samples of shoots were taken stem elongation, boating and heading stages (44, 62 and 80 days from sowing, respectively). At such growth stages, plant fresh weight, plant dry weight, plant height and leaf area as well as the content of total carbohydrates, ctude protein, free amino acids and mineral content were measured. Grain yield per plant and number of tillers as well as some .other characters representing by grain weight per spike, number of grains per spike, lOOO-grain weight, were measured at harvesting time (110 days from sowing). Similarly, the biochemical measurments that carried out in shoots were also determined in grains except of free amino acids that detected only in shoots. Instead, protein amino acids were measured in grains. The obtained results can be summarized as follows: - 164 - :. Salinity Effect2 1. Values of fr cch ·;!eight./plant, Leaf area arid pLan t heigh t vtex:« not grea t Ly aff cc t ed af t CY’ she !,t ) cri.o d 0: salini ty exposure. Howev er-, .;i th pr oLong oo exposure period, the retarding effect of salinity was noticed even under the low’ salinity levels. 2. Dry wei&~t/pl&~t was not greatly affected during the stem c.l onga t.Lon ard boating stages at most levels of salinity. A significant increase, ho~ever, was noticed at the boating stage in plants treated with 6000 ppm level and sometimes with 8000 ppm level. The depressive effect of high salini ty 1 evels app eared only at ’~heheading stage. The lowest level of salini ty (6000 pnn ) ViaS 2till st1.~:.:le..- tive for dry ~eight accumulation. J. Number of tillers was not signific~~tly affected with the application of low salinity level (6000 ppm), whe~eas a signifi cant decrease resul ted ’xith further ri ee Ll salini ty 1 evel . 4. The increase of salinity level has resulted in a significant decrease in grain yield, it ~as enhanced only at the 1st season under low s~linity level (6000 ppm) but being slighly lower than the control at the 2nd season. 5. Numb ar- and Y{eight of grains per spike showed gradual increase vrith increasing salinity levels up to 8000 ppm. - 165 - Values of grain ~eight/spike were more or less similar to the control in the highest salt treatment (12000 ppm), whereas thODe of grain number being still higher. 6. The average weight of lOaO-grains decreased gradually with increasing the level of salinity, in some cases, the lowest salinity level appeared without a marked effect. 7. Total carbohydrate content (gig dry weight) was not greatly affected with most salinity levels at stem elongation and boating stages, a decline in carbohydrate content being noticed at boating stage with the application of either 6000 ppm level or 12000 p)m level. However, the depressive effect of salinity on carbohydrate content became more obvious at the heading stage. 8. Protein content (mg/g dry weight) was not affected at stem elongation stage with the application of 6000- and 8000 ppm tre~tments but tended to decrease with the further rise-in salinity level. In the boating stage, however, the rise in salinity level resulted in a gradual and marked decrease in protein content.” Plants treated ~ith 8000 ppm level showed on the other hand, a marked rise in their protein content. At the heading stage, protein content in plants treated with 6000 ppm salinity level was lower than that of the control, a tendency for recovery was noticed however vdth the rise of salinity level. _. -,’- ..- - ---_.-_ .. _-,. __ .-.~----- - 166 .. 9. Salinity resulted in a marked accillDulatiunof freeamino acids content that being more obvious at the stem elonation stage. The composition of free amino acid pool of barley shoots exhibited remr:.rkablevariations under different levels of salinity and growth stages, as well. The obtained results showee, in general, that salinity had in most samples a pronouncing effect on raising the proportion of amino acids that being de}endent on the activity of Kreb’s cyc~e (K-family), but had, on the other hand, depressive effect for amino acids derived from triose and pyruvic acid (TP-family). Among the former group (K), proline, as a particular recorded a noticeable augment in their content with salinity •. The increas~ in proline content was coincided with a marked decrease in glutarric acid. Aspartic acid was not detected in the free form at any growth stage; instead, B-alanine composed a marked proportion that being increased mostly with increasing salinity level. 10. Gradual accumulation of sodium and chlorides was clearly shovm in most growth stages with the rise in salinity level. On the other hand, potassium content was diminished to some extent at the stem elongation stage with the application of the lowest salinity level (6000 ppm); some fluctuations were noticed, however, vdth further rise in sali~ity level. At the boating stage, however, potassium level remained more or less stable regardless the rise in - 167 - salinity level up to 12000 ppm level, but being diminished gradually at the heading stage with the rise of salinity level. Kg++ content sho~ed in most erowth stages a 2-phase pattern, so it was diminished Gradually ~ith the rise of salinity level:”up to 8000 ppm level, then increased to reach values exceeding those detected in the control ~hen concerning the rise of salinity level from 8000 to 12000 ppm level (2nd phase). Despite the increase in salinity level, Ca++ content, however, appeared in most growth stages more or less similar in the salinized plants but being mostly higher than that of the unsalinized ones. Data reveal, in addition, that salinity had not any marked affect on phosphorus content at the stem elongation and boating stages but being effective only at the heading stage, at which phosphorus content recorded gradual increase by increasing salinity level. 11. Grain analysis reveal that grains produced from plants treated with 6000, 8000 and 12000 ppm salinity levels were lower in th~ir carbohydrate content than those untraated. Vfuereasmore or less similar carbohydrate content to the control was noticed vath the application of 10000 ppm level. Protein content in ·.grainsshowed somwhat increase than the control with the application of 6000 ppm salinity level only, but showed gradual decline with further rise of ·l - 168 - salinity level. Na, K and Mg contents increased in grains with the rise of salinity level. Calcium and phosphorus contents were not greatly affected in most cases. The application of low salinity level (6000 ppm), as being stimulative for protein accumulation in barley grains, induced at the same time a clear effect on amino acid composition and appeared different than that exhibited by high levels of salinity. The application of 12000 ppm salinity level resulted in a greatly altered protein composition, since the detected values for the proportion of amino acids belonging to triose-pyruvic acid family (TP) exceeded those of Kreb~s cycle. The reverse figure appeared, however, when concerning unsaline or low salinity levels. II. Growth Regulators Effects 1. Fresh weight was significantly increased at stem elongation stage vdth the application of growth regulators only at the 2nd.season. Kinetin and to less extent Phosphone were the most effective. Whereas, at boating and heading stages the stimulative effect of growth regulators on fresh weight,that detected at both seasons,was more obvious with the application of Phosphone. Alar, in contrast, was the least effective. The effectiveness of Kinetin appeared, ---- -- --------- - 169 - however, to be more or less similar to that of benzimidazole at boating stage but being lower at heading stage. 2. The applied growth regulators exe~ted in most cases a significant rise in dry weight throughout the growth period particularly when concerning the 2nd season. Comparatively, Phosphone and Kinetin proved in most samples to be the most effective. J. The effect of growth retardants on plant height appeared to be contradictory to that shown with cytokinins. The retarding effect of growth retard~~ts was shovm at both seasons. Cytokinins, however, exhibited always a significant increase in plant height in the 1st season; the same effect was noticed in the 2nd season byt only at heading stage. 4. Leaf area decreased significantly in both season with the application of growth -retardants particularly when concerning later rather than earlier grovah stages. On the other hand, cytokinins appeared more stimulative at the earlier than the later stages. 5. Number of tillers was markedly decreased in both seasons with the application of cytokinins. On the other hand, growth retardants were without a significant effect. 6. Grain yield per plant was significantly increased in ibo th seasons wi th the application of growth regulators, -- -._ .._---~ - 170 - particularly Kinetin and Phosphone. 7. Grain weight per spike increased significantly in both seasons with the application of Kinetin. V~lereas, with other growth regulators, grain weight/spike was significantly increased only in the 2nd season. 8. Number of grains per spike increased significantly in both seasons viith the application of Kine tin and Phosphone. Alar eL~ibited the same effect at the 1st season only. Benzimidazole, in this regard, appeared not effective in both seasons. 9. lOOO-grain weight decreased significantly at the 1st season with the application of Alar and Phosphone. At the 2nd season, a significant increase on lOaD-grain weight exhibited by Phosphone and Kinetin. Benzimidazole, however, had no significant effect on weicht of 1000 groins in both seasons. 10. The application of growth regulators resulted in most cases in a lower carbohYQrate concentration (relative content, mg/g dry weight). Although, at the stem elongation stage, Phosphone and Kinetin resulted in a slight increase in the relative content of total carbohydrates. Absolute content (mg/plant) showed marked increase particularly with Alar and Kinetin at boating and heading stages. On the contrary, marked decrease was recorded with Alar and Phosphone at stem elongation stage and Benzi~dazole at heading stage. - 171 - 11. Crude protein content (relative content) increased during th€ stem e1o~gation and to less extent at the boating stages with most the applied growth regulators, but decreased at heading stage. Absolute content (mg/plant) increased, however, \nth all growth regulators at boating stage, but showed some fluctuations with other growth stages. 12. Free amino acids: a) The application of growth regulators induced in most growth stages a clear increase in the content of total free ami~o acids. At stem elongation stage, the magnitude of such rise appeared greater in case of Alar but tended to decrease gradually vnth the application of Prtosphone, Kinetin and Benzimidazole. Alar at the boating stage was still effective for raising the content of free amino acids, whereas more enhanced effect was noticed with Phosphone and Kinetin. The least rise was noticed, however, vdth Benzimidazole. At the heading stage, however, the stimulative effect of Alar diminished to great extent, whereas that of Phosphone, Kinetin and Benzimidazole was still noticed. b) Data showed, in addition, that the composition of free ami~o acids ap~eared also to be greatly altered with the application of growth regulators. In this regard, the proportion of Kreb’s cycle dependent amino acids (K) recorded a remarkable increase \uth the application of Alar at the stem elongation stage only. Such group of amino acids recorded a similar increase with Phosphone, Kinetin and Benzimidazole only at the heading stage. The increase - 172 - in the proportion of K-group of a~i~o acids appeared to oe mainly attributed to t~e increase in the proportion of B-alanine. On the 0 ther hand, among ami.no acids beloncing to K-group, glutamic acid showed a marked decrease with the application of growth regulators particularly at the stem elongation and boating stages. The reverse effect proved to be true at the heading stage. Proline e7~ibited a marked increase only at stem elongation stage with the a)plica~ion of Alar or Phosphone, whereas the reverse effect was noticed in the other growth stages particularly with cytokinins. Proportion of threonine was diminished in most cases with the application of growth regulators, stimulative effect was noticed only at the stem elongation stage ~~th the application of cytokinins. Accordingly, the ratio of a’nino acids generated from glutamic acid to those generated from aspartic acid (G/A ratio) was in most cases much lower in growth-regulators-treated plants. c) In the other direction, the composition of free amino acids belonging to triosepyruvic acid family (TP) was also a1 tered ”:,t-hi the application of growth reguls..tors. The ratio of pyruvic depe.iderrt amino acids to those of triose (PIT) recorded,vrith most growth regulators, a remarkable rise at the stem elongation and boating stages, ~hereas the reverse being true at the heading stage. The increase in such ratio was attributed mostly to the increase in the proportion of leucine, alanine and sometimes valine. - 173 - 13. Grein analyses reveal that the application of gr-o.r th regulators stimulated in most cases the accumulation of total carbohydrates, whereas the reverse effect was noticed when concerning protein content. Most of the applied growth regulators resulted in the reduction of Na content in grains but being without a~y marked effect on K content. The content of Ca and Mg increased rnarkedly \rithAlar and Benzimidazole·unly, but showed unconsistent effect with other growth regulators. III. Effects of the interaction betv/een levels of salLli ty and growth regulators ,1. All growth regulators,in the 2nd season only, ey~ibited a significant stimulative effect on plant fresh weight during the boating and heading stages under 1000 and 12000 ppm level of salinity. Similar effects were shown by phosphone treatment under 6000 and 8000 ppm level at boating and heading stages. 2. Dry weight/plant was significantly increased at most growth stages in the 2nd season only with the application of Phosphone and Kinetin in most salinity levels. J. Generally, the cytokL:ins, Kinetin and Benzimidazole, exhibited stimulative effect on plant height under most levels of salinity in two seasons. On the other hand, growth retardants, Alar and Phosphone, appeared depressive for plant height at most levels of salinity. - 114 - 4. Leaf area was not significantly affected, in both seasons, by the interaction between salinity levels and growth regulators at stem elongation stage. On the other hand, Alar and Phosphone showed remarkable retarding effect on leaf area under moderate salinity levels (8000 & 10000 ppm) at boating and headin6 stages. However, cytpkinins resulted at heading stage only in a significant increase of leaf area at the high levels of salinity (10000, 12000 ppm) 5. At the 1st season only, cytokinins induced a depressive effect on ti1lering number under the low salinity level (6000 p~m) only. Whereas, the reverse behaviour was observed only with Alar under 8000 ppm level of salinity. No significant effect has been detected at the 2nd season. 6. Kinetin and Phosphone exhibited stimulative effect on grain yield/plant under most of the applied salinity levels. The stimulative effect of Benzimidazole on yield/plant that has been detected at the 2nd season only appeared to be exerted under low rather than high salinity levels. 7. At the 2nd season only, Phosphone and Kinetin induced a stimulative effect on grain weight/spike at most of the applied salinity levels. Benzimidazole appeared effect~ve only at 8000 ppm level. Vfuereas,Alar being effective under 10000 ppm salinity level. No significant effect has been detected at the 1st season. --- -- ----------------------------- --- - 115 - s. Si~nifica~”1t interaction on grain nur:lber/spike ’::as schieved only at the 1st season. Phosphone and Kinetin were efi’ective on rai sing the nuube r of grains/spike at most levels of salinity. Alar, however, appeared stimulative at 10000 ppm salinity level oaly. Benzimidazole appeared without any significant effect. 1000-grain weight decreased significantly under unsaline conditions with Alar and Phosphone 9. The relative content of total carbohydrates increased markedly at stem elongation stage with the application of Alar and benzimidazole under 10,000 P?m salinity level. Also, Benzimidazole was still stimulative for carbohydrute accumu- Laci on at 6000 and 12000 ppm levels. On the other hand, depressive effect was shovm always with Phosphone and Kinetin but being detected at 12000 ppm level when concerning Alar. At the boating stage, relative content of carbohydrates, showed marked increase vrith most of the applied growth regulators at 6000 and 12000 ppm levels, whereas the reverse being true at 8000 and 10000 ppm levels. At the heading stage, Phosphone appeared enhansi,ve for car-bouydz-a t e accumulation at most levels of salinity, whereas no consistent effect was noticed with other growth regulators. 10. The relative content of crude protein that showed somewhat increase at stem elongation stage with the application of growth regulators under unsaline conditions, tended to be counteracted with most levels of salinity. However, - 116 - at the boating stage, growth regulators appeared more effective in inducing crude protein accumulation under saline conditions, particularly hioh salinity levels as compared with their effect under unsaline conditions. Although, at the heading stage, growth regulators exhibited some depressive effect under unsaline conditions; stimulatory effect had been shoym mostly under 6000 & 8000 ppm levels but tended to disappear under other salinity levels. 11. The ability of growth regulators-treated plants to accumulate free a~ino acids under unsaline conditions appeared to be varied greatly with the application of different salinity levels. In this regard, the applied growth regulators were still effective for inducing the accumulation of free amino acids either under the low or the highest salinity levels. Vlhereas, under moderate salinity levels (8000 & 10000 ppm), where the accumulation of free amino acids was more obvious, the application of growth regulators counteracted, in most cases, the ability to accumulate free amino acids. The application of growtt regulators under different levels of salinity had resulted in a clear regulatory effect on the compositional characteristics of free amino acids pool as indicated from the values of the ratios : Kreb’s cycle dependant amino acids/Triose-Pyruvic-derived amino”acids (K/TP ratio), Glutamic-generated amino acids/ - 177 - Aspartic acid-generated runinoacids (G/A ratio) and Triosegenerated amino acids/Pyruvic a~td-generated amino acids (T/P ratio). In this regard, the applied growth regulators induced at any salinity level a clear enhancement for raising the K/TP ratio at the stem elongation stage. However, at the boating stage and heading stage where the enhansive effect of salinity on K/TP ratio was more obvious, growth regulators exhibited variable effect according to the ~ype of growth regulators and salinity level, as well. In the other hand, the effect of 6rowth regulators on G/A ratio appeared less fluctuated as compared with that noticed under most levels of saliDity irrespective to tfietype of the applied growth regulators. The magnitude of such augment in G/A ratio was ~ore greater with the interaction as compared with that of salinity or growth regulators separately. In addition, a clear tendency for raising the ratio; G/A, was noticed wi th growth advancement reaching, in most cases, t~ie highest value at the heading stage. The rise in G/A ratio appeared to be related ~~th the increase in the proportion of proline particularly under lower rather than higher levels of salinity. Glutamic acid, that showed low proportion vdth growth advancement, tended to be accumulated at the boating stage due to the effect of growth regulators under most levels of salinity. Concerning B-alanine, that belonging to aspartic acic group, data reveal that the applied growth regulators particularly cytokinins appeared in most growth stages to oe vrith a depressive effect - 178 - at 6000 ppm level, wher-e a.sthe reverse proved ture at the stem elonation and boating stages.as far as the highest level of salinity is concerned. However, under moderate level of salinity (8000 & 10000 ppm) the application of growth regulators diminished, in most cases, the proportion of B-alanine, though a somewhat increase was noticed with Phosphone. 12. Data of the mineral balance reveal that values of KINa ratio, that showed a substantial decrease with tilerise of salinity level, tended to be corrected with the application of growth regulators at 6000 ppm level at the stem elongation stage as well as under leOOO ppm level at the boating stage. The reverse effect was shovm, hOTIever, lath other levels of salinity. On the other hand, marked depressive effect of growth regulators on KINa ratio was clearly shovm in most levels of salinity at the heading stage. In addition,. the ap)lication of growth regulators enzhanced, in most cases, the rise in the values of Ca+Mg/Na+K ratio at 8000 ppm salinity level, but being less effective at 10000 and 12000 pm levels. On the other hand, the ap~lication of gro\r.th egulators at 6000 ppm level tended, to great extent, to counteract the depressive effect of salinity on K/Ca ratio, vhereas the reverse being true ~v.itht~herise of salinity eve1. 13. Grain analyses showed that carbohydrate content in rains of plants treated with salinity exhibited marked ---~-~ .. _-_... _~~~- - 179 - r€ase, as compared with those of the control, with the application of Phosphone and Alar. Less effect was noticed, however with Benzimidazole, whereas no marked effect could be detected vrhen concerning Kinetin. Protein content decreased in most cases wi~h the interaction treatments, but being increased only under 12000 ppm salinity level. At such high salinity level, Phosphone appeared the most effective for raising protein content in grains. Composi tional characteristics of gz-af.n-ep ro t e.Lncanu.no acids had been greatly altered wi~h the application of growth regulators under different salinity levels. All the applied :growth regulato~s were able to enhance the rise of K/TP ratio under the highest level of salinity, ~hereas any 6f them xtent under the highest level of salinity (12000 ppm). |