INFLUENCE OF FOLIAR APPLICATION OF ZINC ON SEED YIELD AND ITS COMPONENTS IN SOME ALFALFA VARIETIES

This study was carried out at the experimental farm College of Agriculture; Abu-Ghraib, Baghdad, Iraq during from end of march 2014 to mid of August 2015. The main objective was to find out the effect of zinc concentration (0, 30, 60 and 90) mg.L -1 on seed yield and its components of four alfalfa varieties (Local, Hamaddan, Vernal and Lodi). Layout of the experiment was R.C.B.D arranged within split –plots with three replications. Zinc concentration were used as main plot, while varieties were used as sub-plot. Results, showed that foliar application of zinc at concentration more than 30 mg.L -1 (60 and 90 mg.L -1 ) resulted in a significant increment in the No. of ovules floret -1 , No. of seed pod -1 , No. of stems m -2 , No. of racemes stem -1 , No. of pods raceme -1 and seed yield. Kg.ha -1 in contrast, percent of ovules abortion was significantly reduced, while 1000 seed weight was not significantly influenced by Zinc concentrations. Highest seed yield (535.0 Kg.ha -1 ) was obtained when Zinc added at level 60 mg.L -1 . Local var. produces higher No. of ovules floret -1 , No. of seed pod -1 , No. of stem.m -2 , and No. of racemes stem -1 and it was significantly different than other varieties except var. Hamddan. Increasing of all these traits resulted in increasing of seed yield in local var. (532.5 Kg.ha -1 . There was high positive correlation between seed yield and each of seed set, No. of stem. m -2 and No. of pods raceme -1 (+ 0.75**, +0.66** and 0.78**) respectively. This result may be indicating that these traits could be used as good selection criteria for breeding and improving seed yield in alfalfa varieties. highest seed yield (620.2 Kg.ha -1 ) can be obtained by seeding local variety. and spray the stands with Zinc at concentration 60 mg.L -1 . Keyword: ovules fertility, seed set, trace elements. ةيقارعلا ةيعارزلا مولعلا ةلجم 1028 : 44 ( 3 :) 345 352 طيبرخ تجلا فانصا ضعب يف ةتانوكمو روذبلا لصاح يف كنزلا شر ريثأت طيـــــبرخ فمخ ديمح ذاتسأ ليصاحملا مسق ةيمقحلا ةعا رزلا ةيمك – دادغب ةعماج hameedkhrbeet@yahoo.com صمختسملا لقح يف ةسا ردلا ةذه تيرجا ةعا رزلا ةيمك / دادغب ةعماج – راذا رهش ةياهن نم ةرتفمل بيرغ وبا 2014 رهش فصتنم ىلا أ ب 2015 كنزلا زيكا رت ريثأت ةسا ردل كلذو ( 0 ، 30 ، 00 و 00 .مغمم ) رتل 1 لصاح يف روذبلا ل ةتانوكمو يمحملا( يه تجلا نم فانصا ةعبر و نادمه Lodi, Vernal, ) . فو ىمع ةفشنملا حاوللاا بيترتب ةبرجتلا تذفن ةاشعملا ةمماكلا تاعاطقلا ميمصت ق تمتحا اذا تا رركم ةثلاثب لا كنزلا زيكا رت م لا فانصلاا تمتحا امنيب ةيسيئرلا تلاماع م زيكرتب كنزلا شر نا جئاتنلا ترهظا . ةيوناثلا تلاماع أ نم ىمع 30 رتل.مغمم 1 ( 00،00 رتل .مغمم 1 ةيونعم ةدايز ىلا ىدا دق ) دع يف ةدحاولا ةريهزلاب تاضيوبلا د ، ةنرقلاب روذبلا ددع ، دع عبرملا رتملاب ناقيسلا د ، دع دحاولا قاسلاب ةيرهزلا تاوونلا د ، تانرقلا ددع ا ونل هر و ةيرهزلا لصاح روذبلا و مل امنيب . تاضيوبلا ضاهجا ةبسن يف يونعم ضفخ ىلا نزو ايونعم رثاتت 1000 ةرذب . طسوتم ىمعا غمب روذبلا لصاحل 535 ك ـه.مغ 1 زيكرتب شرلا دنع 60 رنل .مغمم 1 ىطعا .كنزلا نم يوبلا ددعل طسوتم ىمعا يمحملا فنصلا ناقيسلا ددعو ةنرقلاب روذبلا ددعو ةريهزلاب تاض م 2 ةرونلاب تانرقلا ددعو ىمع ايونعم قوفتو لصاح غمبو نادمه فنصلا ءانثتساب فانصلاا عيمج روذبلا يمحملا فنصلا يف 535.5 مغك . ـه 1 دجو . فانصلاا عيمج ىمع اقوفتم بترا لصاح نيب بجومو ةيونعملا يلاع طا روذبلا . روذبلا ددع نم لكو نرقلاب ناقيسلا ددعو ة م 2 ةرونلاب تانرقلا ددعو غمب ةيرهزلا +0.78**,+0.66**, +0.75** يلاع تجلا نم فانصا ةيبرتل رايعمك تانوكملا ةذه لامعتسا نكمم كلذل عباتتلاب ة نم لصاحلا روذبلا نم لصاح ىمعا نا . روذبلا مت ( ةيمع لوصحلا 620.2 ـه.مغك 1 زيكرتب كنزلا شرو تجلا نم يمحملا فنصلا ةعا رز دنع وه ) 60 مغمم . رتل 1 . ةيحاتفم تاممك تاضيوبلا ةبوصخ : ، روذبلا دقع ، . ىرغصلا رصانعلا *Received:20/12/2017, Accepted:18/3/2018 Iraqi Journal of Agricultural Sciences –1028:49(3):345352 Khrbeet 543 INTRODUCTION Alfalfa (Medicago sativa L) is one of the most perennial legume crops in Iraq and worldwide. It is well known capability of nitrogen fixation and a superior source for forage due to its high nutritional quality and herbage production (1,30). Alfalfa grown for seeds, needs different environmental conditions and specific agronomic practices (6). In Iraq, alfalfa is cultivate mainly for forage production and seed yield is considered to be of only secondary importance. The mean seeds yield under Iraqi condition is low, no more than 250 kg ha -1 (18). This low productivity can be attributed mainly to a lack of suitable guide lines for its management, particularly during the critical period of seed crop. Genetic diversity for seed yield and its components in alfalfa was described between and within population by Bolanos-Agilar and et al. (5), similarly genetic variation was identified for ovule fertility, ovules number and sterility (20, 31). At the experiment carried out in Agricultural Faculty in Turkey (23) to determine alfalfa seed yield and its components in sixteen variety. He found that seed yield per unit area was significantly positively correlated with the number of seeds inflorescence -1 , number of pods inflorescence -1 and seed weight inflorescence -1 , suggested that these yield components may be good selection criteria to improve seed yield of alfalfa cultivars. All nutrients must be available in sufficient quantity in order to be able to get satisfactory seed yield (10). Zinc (Zn) is among those micronutrients which are most often deficient, availability of Zn is largely dependent on soil pH value and it is higher in acid soils, contrary to this, in alkaline soil, its availability is very low. Deficiency is more likely on soils with pH greater than 6.0 (21). Whereas most of soils in central and south of Iraq had pH more than 7.5 (4), therefore addition of Zn as foliar application to foliage rather than soil medium is great importance. Zn is involved in pollen fertility, pollen production and pollen tube elongation (19,24) so that its deficiency can cause to decrease in seed formation and subsequent yield reduction. It is also promoting nodulation in leguminous plants (26). In the present study an attempt has been made to understand the performance of reproductive growth of contrasting alfalfa cultivars under different zinc regimes. MATERIALS AND METHODS This experiment was performed at experimental station of the Coll. Agric., Univ. Baghdad during the period from end of March 2014 to mid of August 2015, soil analysis of the field shows in Table 1. Table 1. Some chemical properties of the


INTRODUCTION
Alfalfa (Medicago sativa L) is one of the most perennial legume crops in Iraq and worldwide.It is well known capability of nitrogen fixation and a superior source for forage due to its high nutritional quality and herbage production (1,30).Alfalfa grown for seeds, needs different environmental conditions and specific agronomic practices (6).In Iraq, alfalfa is cultivate mainly for forage production and seed yield is considered to be of only secondary importance.The mean seeds yield under Iraqi condition is low, no more than 250 kg ha -1 (18).This low productivity can be attributed mainly to a lack of suitable guide lines for its management, particularly during the critical period of seed crop.Genetic diversity for seed yield and its components in alfalfa was described between and within population by Bolanos-Agilar and et al. (5), similarly genetic variation was identified for ovule fertility, ovules number and sterility (20,31).At the experiment carried out in Agricultural Faculty in Turkey (23) to determine alfalfa seed yield and its components in sixteen variety.He found that seed yield per unit area was significantly positively correlated with the number of seeds inflorescence -1 , number of pods inflorescence -1 and seed weight inflorescence -1 , suggested that these yield components may be good selection criteria to improve seed yield of alfalfa cultivars.All nutrients must be available in sufficient quantity in order to be able to get satisfactory seed yield (10). Zinc (Zn) is among those micronutrients which are most often deficient, availability of Zn is largely dependent on soil pH value and it is higher in acid soils, contrary to this, in alkaline soil, its availability is very low.Deficiency is more likely on soils with pH greater than 6.0 (21).Whereas most of soils in central and south of Iraq had pH more than 7.5 (4), therefore addition of Zn as foliar application to foliage rather than soil medium is great importance.Zn is involved in pollen fertility, pollen production and pollen tube elongation (19,24) so that its deficiency can cause to decrease in seed formation and subsequent yield reduction.It is also promoting nodulation in leguminous plants (26).In the present study an attempt has been made to understand the performance of reproductive growth of contrasting alfalfa cultivars under different zinc regimes.

This
experiment was performed at experimental station of the Coll.Agric., Univ.Baghdad during the period from end of March 2014 to mid of August 2015, soil analysis of the field shows in Table 1.
Table 1.Some chemical properties of the soil *

* Analysis carried out in ministry of sciences and technology labs
The previous crop before study establishment was corn (Zea mays L).The grass stand was plowed and fallow for four months before establishment of alfalfa study.The experiment was carried out in a (R.C.B. D) arranged in split plot with three replications.Four levels of Zinc (Zn) (0, 30, 60 and 90) mg.L -1 referred as Z n0 ,Z n1 ,Z n2 and Z n3 respectively as main plots (chelate EDTA 15% Zn was used as a source for Zinc) and four cultivars of alfalfa (Local, Hamaddan, Vernal and Lodi) (Table 2) were randomly assigned on each of the main treatments as a sub-plots P,K and S were added before sowing as recommended (12,14,17) in the end of march 2014 seeds of each cultivar were established in 60 cm drills at seed rate 8 kg ha -1 (12,13).Each sub plot consisted of five rows, each three meters along.Cutting for forage was made when plants reached the 15-20% flowering stage.The stands were not left for seed crop during the first year because in second year the stands reach the best age for seed yield (3).All plots were hand weeded during summer 2014 and subsequent time when it is necessary.Last cutting was made on 10 th Mey 2015 and crop left for seed set because this time lead the plants to reach flowering on the best time for insect's pollinators (Table 3).The intervals of irrigation were organized and last irrigation was done when the stands reached at beginning of pod formation stage (22).Foliar application of nitrogen (1000 mg.L -1) and

Biological Measurement:
In each sub-plot when the stand reached full bloom stage, ten inflorescences were randomly chosen from the middle rows.sub sample of one floret was taken from the middle section of each inflorescence to calculate the number of ovules per floret using microscope, the ovary was removed from the calyx and corolla, the ovules dissected out and then counted.Quadrate (0.6 m -2 ) was taken from the middle row and harvested when the majority of pods had turned brown (11) to determine the number of stems quadrate -1 and then convert to m -2 .Fifty stems were selected at random and following seed yield components were determined: -Number of rasemes.stem -1 Number of pods.rasemes -1 .Number of seeds.pod - .1000 seed weight (g) (T.S.W).Seed yield was estimated from the middle lines, drying were made in the field and threshing was made by hand.% Ovules Abortion was determined according to following equation:

Abortion % =
All data collected from this experiment were analysis according to analysis of variance method as described by Steel and Torrie (25).Means were compared using L.S.D test at 5% level of significant.Simple correlation analysis was carried out using SPSS software version 20.

RESULTS AND DISCUSSION
Number of ovules floret -1 , Seed set and % of ovules abortion: Seed pod -1 (seed set) is an important index which relate to the number of ovules ovary -1 and the success rates of seed set.The ovule number reflects the potential number of seeds that could be produced pod -1 , under Iraqi conditions, alfalfa plants produce seven to twelve ovules floret -1 , but only a few ovules developed successfully into seeds (16).There were also significant differences between varieties in number of ovules ovary -1 and seed set, while there were no significant differences between varieties in % of ovules abortion Table 5 shows that the Local var.produced highest No. of ovules (8.2) and highest seed set (5.29) and it was significantly differed from other varieties except var.

Results shows in
Hamaddan and the latter was not significantly different to each other's.This is not surprising since.Local var. was more adapted to local condition.This results was in agreement with results found by Wang, et al (31) who stated, that there were significant differences in ovules number ovary -1 and ovules fertility among nine varieties of alfalfa.In order to breed high seed yield varieties, plants with more number of ovules ovary -1 may be could result in maximum seeds pod -1 (seed set).positive correlation between No. of ovules and seed set gave a good evidence for previous statement, (Table 9).Table 4. Effect of zinc levels on mean number of ovules ovary -1 , seed set and % of ovules abortion  (23).Foliar application of Zinc (Zn) up to Zn 2 (60 mg.L -1 ) significantly increase the number of racemes stem -1 and number of pods raceme -1 (Table 7) , However, increase the level beyond that limit reduce those two parameters, but such reduction was not significant.In this study the number of raceme appeared over the growing season was higher at Zn 2 (14.49) and Zn 3 (13.28)and lowest at Zn 0 (10.33).

Table 2 . Varieties used in the experimentTable 3 . weather condition during April-End of July 2015 of Abu-Ghraib * *Meteorological data obtained from Al-Raid station, Abu-Ghraib
Table 4 indicate that foliar application of Zn at level 60 mg.L -1 produced highest number of ovules ovary -1 (8.33), seed set(5.63)and less proportion of ovules abortion (32.16) and it was significantly different from other levels of Zn except high level (90 mg.L -1 ) .the soil analysis of this