Effect Of Fertilization And Some Growth Regulators On Growth, Flowering, Fruit Yield And Quality Of Okra:

Said Mowoad Mohamed Eid

The present investigation was carried out throughthe two successive summer seasons of 1982 and 1983 atthe Experimental Farm at the Faculty of Agriculture atMoshtohor. Four experiments were conducted to studythe effect of fertilization and some growth regulatorson vegetative growth, flowering behaviour, fruit yieldand quality of okra plants.The First Experiment:This study was performed to investigate the influenceof three phosphorus levels; 0, 32 and 64 kg P2OS/fad.within three potassium levels; 0, 24 and 48 kg K2O/fed.on growth, chemical composition of plant foliage, floweringcharacteristics, fruit yield and quality of okra plants.The main results could be summarized as follows:1. Phosphorus application at its medium level (32 kgP20S/fed.) significantly promoted stem diameter, freshand dry weigQt of plant foliage than either the highestlevel (64 kg P20s/fad.) or the control treatments. Moreover,increasing phosphorus levels up to 64 kg P20S/fed. hadthe most favourable effect on number of branches andleaves per plant. The application of 24 kg K20/fad.significantly increased number of leaves, fresh and dryweight per plant compared with that received 48 kg K20/fad.or the control. Meanwhile, stem length and number ofbranches per plant were not significantly affected due topotassium application.With regard to the combined effect of phosphorus andpotassium on plant growth characteristics, it was noticedthat the medium level of both nutrients (32 and 24 kg P20Sand K20/fad. respectively) proved to be the best treatmentin increasing fresh and dry weight of plant foliage. Okraplants received 64 kg P20S within 48 kg K20/fad. exceed.edother plants regarding number of leaves per plant.2. Phosphorus application at 32 kg P20s/fad. had apronounced significant effect in increasing N, P and Kaccumulation in okra plant foliage as compared with theheavy P-application (64 kg P20S/fad./ or the control treatments.Moreover, there was an increasing trend of totalcarbohydrates accumulation in okra plant foliage withincreasing levels of P-fertilization as compared with thecontrol.Potassium application generally seemed to promoteN, P,K and total carbohydrates accumulation in okraplant foliage. Plants supplied with 24 kg K20/fed. weresuperior in this respect. Heavy K-application (48 K20/fed.)significantly depressed such studied items. The combinationof phosphorus and potassium fertilizers at their mediumlevels (32 kg P20S and 24 kg K20/fad.) showed generallythe most enhancing effect in increasing nutrients accumulationin okra plant foliage.3) Phosphorus application significantly acceleratedflowering time for about 3-4 days. Howeverl number offlowers per plant and fruit setting percentage were notsignificantly affected as a result of phosphorus application.Phosphorus fertilizer especially at its highestlevel (64 kg P20s/fad.) significantly increased number ofnodes that bearing the first flower.Potassium application slightly enhanced all studiedflowering characteristics, but the differences failed tors&ch the level of significance.Flowering characteristics were mainly affected byincreasing levels of P-fertilizer except the position ofthe first flower which responsed to either P and/or Kapplication. Thus plan ts supplied wi th ° kg P205 wi thin”48 kg K20/fad. produced its first flower at the lowestnode position.4. Phosphorus application did not exert promotiveeffects on average fruit weight, number of fruits per plantlfruit yield per plant, early and total fruit yield perfeddan as compared with the control treatment.Potassium application, especially at the highest level(48 kg K20/fed.), led to a significant increase in averagefruit weight, fruit yield per plant, early yield and totalyield per faddan as compared with either the lowest levelof K fertilizer or the control treatments. Meanwhile, no-161 -significant differences could be detected in number offruits per plant as a result of K-application. No significantdifferences could be detected between the interactionaltreatments with respect to average fruit weight,number of fruits and fruit yield per plant as well as perfaddan. However, the use of ° kg P205/fad. combined with48 kg K20/fad. tended to improve fruit yield and itscomponents.~5. P-fertilization generally decreased N, P, K andtotal carbohydrates accumulation in fruits of okra plant.K-application seemed to promote gradually the accumulationof N, P, K and total carbohydrates accumulation in fruitsof okra plant. K-application seemed to promote graduallythe accumulation of N, P, K and total carbohydrates. N aswell as K content of fruits were significantly increasedby the use of ° kg P205 combined with 48 kg K20/fad. P andtotal carbohydrates accumulation in fruits were not significantlyaffected by phosphorus and potassium fertilizercombinations.The Second Experiment:This study was performed to investigate the influenceof five varieties; 8alady, Eskandarani, White velvet,Golden Coast and Clemson Spineless within three plantingdaLes; March 20th, April 5th and April 20!h on growth,chemical composition of plant foliage, flowering characteristics,fruit yield and quality of okra plants. Themain results could be summarized as follows:1. The cvs, White velvet and Eskandarani possessed thehighest vegetative growth characteristics as stemlength and diameter, number of leaves and branches andfresh and dry weight per plant. Balady and Goldencoast were intermediate, meanwhile Clemson spinelessranked last in this respect.With regard to planting date it was found that okraplants grown in April 20~ were of longer and thickerstems. The highest number of leaves, fresh and drywe ight pe r plant we re obt ained when plant s we re grownin March 20.!.!2, followed by April 20 tho The cvs ,Eskandarani and White velvet showed the best adaptationand responsiveness to all planting dates, especiallyto the first one (March 20.!b).2. Plants of cv. Eskandarani exceeded these of all othercultivars in N content of their foliage, followed byBalady and white velvet. With regard to P, K and totalcarbohydrates accumulation, White velvet plants werethe best of all cultivars, followed by Eskandaran1.Other cultivars i.e., Balady, Golden Coast and ClemsonSpineless sho~ed no significant differences betweeneach other in this respect.The first planting date (March 20~) showed thehighest N, P, K and carbohydrates accumulation in plantfoliage. Plants of cv , Clellson Spineless showed thehighest N and these of cv. White Velvet showed thehighest p, K and carbohydrates accumulation in theirfoliage, especially when grown at the earliest plantingdate (March 20lh)·3. The least days elapsed from seed sowing to the anthesisof the first flower were observed by plants of cvs .Clemson Spineless and White vslvet, where&s these ofBaledy ~erc the 1~te5t ones. The same trend was alsonoticed with regard to the first flower position.Studied varieties did not show significant differencesregard ing num be r of flowe rs pe r plant, whe reas a sIi ghtrelative increase in fruit setting percentage wasdetected by Eskandarani and Golden coast.Delaying planting date from March 20!b up to April20th pushed plants gradually to flower earlier andalso affected positively the first flc·wer”nodeposition. However, contra trend was noticed concerningnumber of flowe rsper plant and fruit setting percentage.The cv. Clemson Spineless sown late in April, 20thshowed the shortest period required for the anthesis ofthe first flower, although no significant differencesbetween used cultivars within all planting dates weredetected. Among all cultivars, clemson spineless andGolden coast showed the lowest position of the firstflower within all planting dates. The highest numberof flowers per plant was obtained by cvs . White Velvet,Balady and Clemson Spineless for the first, second andthird planting dates, respectively.4. Introduced cultivars, i.e., White Velvet, Golden Coastand Clemson spineless exceeded local ones; Ba]ady andEskandarani in fruit yield characteristics. plants of cv.White Velvet produced the highest number of fruits perplant as well as the highest fruit e arLv yield, meanwhilethese of Golden coast and fruit yield per plant as well asper feddan. Early planting (March, 20.!.b,.)followed by thesecond one (Ap ril, 5!!:!.) imp roved all fruit yield cha racteristicswith the exception of average fruit weight. Thecvs. white Velvet and Golden Coast exceeded the remaindercultivars in fruit yield productiVity, especially whengrown at the first planting date (March, 20th). , -5. Okra plants of cvs. Golden Coast followed by White Velvetand Clemson Spineless surpassed these of local ones 1.e.,Balady and Eskandarani in total N, P, K and carbohydratesaccumulation in their fruits. The second planting datemostly increased fruit nutrients accumulation, followed bythe first one, whereas, the late planting date ranked lastin t his respee t •Plants of cv. Golden Coast showed best responsivenessin P accumulation in their fruits for all planting dates.-165 -With regard to carbohydrates accumulation, cvs. WhiteVelvet and Clemson Spineless were superior in the firstand second planting dates, respectively- Concerning NandK accumulation in fruits, differences were not significant.-The third experiment:This study was performed to investigate the effectof salinity and variety on growth, chemical composition,flowering and fruit yield of okra. This experimentincluded 35 treatments’which were the combinations of7 levels of salinity (tap water + 60, sO and 100 meq./Lfor each of the two salts; NaCl and Na2S04) within 5varieties (Balady. Eskandarani, White Velvet, GoldenCoast and Clemson Spineless). The main results can besummarized as follows:1. The application of NaCl or Na2S04 at 60 and SO meq./Lsi9n if icant Iy dec reased plant fresh and dry we ightthan the control. However, the application of 100meq./L promoted it. The cv. White Velvet wasfavourably responsed to salinity application. Meanwhile,contra trend was observed by cv. Balady.The application of NaCl or Na2S04 at 60 meq./Lhad a depressive effect on plant height compared withthe control. However, NaCl at 100 meq./L and Na2S04at 80 meq./L enhanced significantly plant height. Thecv. White Velvet was favourably responsed to NaCIespecially at the highest dose of 100 meq./L. Meanwhilecv. Balady seemed to be the most sensitive variety inthis respect.2. A. The cvs. Eskandarani. White Velvet and Golden coastshowed the highest chlorophyll a. b and caroteneThe chlorophyll a, b and carotene differed amongvarieties depending on the specific ion effect, dosesand sources of salts.B. The cvs. Clemson Spineless and Golden Coast showedthe highest polyphenol oxidase activity. Meanwhile,maximum activity of peroxidase enzyme was differed amongGolden Coast, Balady and Eskandarani according to theseason of growth.The application of NaCI at 60 meq./L showed ade pre ssive effect on polyp henol oxidase act ivij:-ybutat 80 and iDa meq./L an increase in such activity wasdetected. Increasing levels of Na2S04 tended todecrease the polyphenol oxidase activity, especiallyat the highest dose i.e., 100 meq./L. The behaviourof NaCI on peroxidase activity was much similar tothat of NaCI on polyphenol oxidase activity. Meanwhilethe use of Na2S04 at 60 or 80 meq./L led to a decrementin the activity. However, versus state of incrementwas noticed at 100 meq./L.The cv. Golden coast showed the highest activity ofpolyphenol oxidase enzy.e especially when supplied with100 meq./L of NaCl. Meanwhile, the cv. Eskandaraoishowed the most increase in peroxidase enzyme activityespecially at 100 meq./L of NaCl. The cv. Baladyshowed a decrement in peroxidase activity as a resultof all salinity treatments.C. The cv. White Velvet surpassed other varieties in N,P, K and total carbohydrates accumulation in plantfoliage. Meanwhile, the Clemson Spineless ranked lastin this respect. NaCl or Na2N04 application at 60 and80 meq./L significantly decreased the accumulation ofN, P, K and total carbohydrates compared with thecontrol. However, the application of 100 meq./L eitheras NaCl or Na2S04 promoted significantly the accumulationof such nutrients. The cv. white Velvet responsedfavourably to NaCl and Na2S04 especially at the highestdose i.e., 100 meq./L. Meanwhile, the cv. Balady showedthe most negative responses in the accumulation of thesenutrients by all salinity treatments.3. The cvs. White Velvet and Clemson Spineless requiredthe least number of days for flowering meanwhile, cvs.Balady and Eskandarani might be considered as latevarieties. The NaCI or Na2S04 application at 60, 80and 100 meq./L led to an enhancement of flowering. Okraplants of cvs. Clemson spineless and White Velvet showedthe most favourable response and flowe red ea rllerespecially ”at 100 meq./L of either NaCI or Na2S04•4. The cv. Clemson Spineless showed the largest and cv.Balady expressed the smallest average fruit weight.Meanwhile’, the ev , Balady showed the highest fruitnumber followed by White Velvet, Eskandarani, GoldenCoast and Clemson Spineless, Moreover, the cv. ClemsonSpineless surpassed the other varieties with respectto total fruit yield.The fruit number was increased as a result of NaC!and Na2S04application. Total fruit yield of okraplant was increased as a result of either NaCI orNa2S04 application at any used rate. The cv. ClemsonSpineless surpassed other tested varieties and producedthe highest fruit yield especially at 100 meq./L of -~ .ei t ”e r sal t s •Fourth Expe riment:This experiment was conducted to study the effectof some growth regulators and salinity on growth, chemicalcomposition, flowering and fruit yield of okra. Thisexperiment included 49 treatments which were t he combinationsof (7 concentrations of some growth regulators i.e ••GA3, NAA and eee each with two cone. i.e., 25 and 50 ppmof GA3; 50 and 100 ppm of NAA as well as 100 and 200 ppmof eee plus the cant ral which was distilled water) within(7 levels of salinity i.e., control (Tap water) + 60,80and 100 meq./L to each of NaCl and Na2S04). Obtainedresults could lie summarized as follows:1. The application of either GA3• NAA or ece within allused doses significantly depressed plant growth thanthe cont rol • Fres hand dry weig ht pe r plant were higherin plants sprayed with NAA followed by GA3 and low in. plants sprayed with ecc whereas no significant varianceswere detected in plant growth due to the concentrationso f e a c h 9 ro wt h re 9 u1a tors •NaCl or Na2S04 application had a depressive effecton fresh and dry weight of okra plant as compared withthe control treatment.Most growth ~egulator treatments i.e., GA3, NAA orCCC within all used concentra tions failed to increaseplant 9 rowt h than the cont roI which unsp rayed wit h 9 rowt hregulators. However, no significant effect in increasingplant height compared with those sprayed withdistilled water as a result of growth regulator treatmentswas detected.NaCl or NaZS04 application had a depressive effecton plant height of okra as compared with the controltreatment. Increasing the salinity level of irrigationsolution from 60, 80 to 100 meq./L gradually tended toreduce okra plant height.GA3 at 50 ppm combined with 60 or 80 meq./L ofeither salts promoted plant height as shown in 1982season. The application of NAA at 50 ppm decreasedplant height 0 f 0 kra grown unde r 80 & 100 meq ./L ofNaCl and 60 & 80 meq./L of NazS04• The applicationof eee at 100 or ZOO ppm makes okra plants more tolerant~o salinity application i.e., 60, sO or 100 meq./L eachof NaCl or Na2S042. A. Spraying okra plants with NAA especially at 50 ppmhad the highest chlorophyll-a and the lowest chlorophyll-bcontent as compared with the other growth regulatortreatments. whereas, plants sprayed with ecc had thelowest chlo rophyll-a and the highest chlo rophyll-b andcarotene content.Increasing levels of NaG! and Na2S04 gradually decreasedchlorophyll a. b and carotene content of leaves. Varianceswere more pronounced between the low and high levelof salt application i.e., 60 and 100 meq./L.Spraying plants with GA3 had no promotive effect onchlorophyll-a & carotene but had a ~romised effect onchlorophyll-b, that is. in plants grown under salinitystress. Using NAA at 50 ppm had a favourable effecton chlorophyll-a content in plants grown under 60 end80 meq./L of Na2S04• The same concentration of NAA hadnot the same effect with NaCl. The chlorophyll-b showedan increase and carotene content a decrease as a resultof the NAA interaction within salinity. Meanwhile,spraying plants with eec had no effect on chlorophyll-aincrement. The chlorophyll b showed response to CCCapplication and carotene content were increased in plantsgrown under salinity levels .•fB. The g rowt h regulato rs low concant rations led toincrement in the activity of polyphenol oxidase andperoxidase significantly.The low doses of NaCl and Na2S04 led to an increase.in polyphenol and peroxidase enzyme activity.GA3 led to an increase in the aC~lvity ~f polyphenoloxidase in plants grown under salinity. Meanwhile, theperoxidase activity was decreased when sprayed with GA3especially at 25 ppm. The same trend was noticed inplants sprayed with NAA. The ece spraying led todecrement in polyphenol oxidase activity especially atthe highest doses of salts. The same trend was noticedwith peroxidase activity but Na2S04 at 100 meq./L ledto slight increment in the activity.G. The control treatments surpassed those sprayed withgrowth regulators in nutrients accumulation of N, P, K andtotal carbohydrates .. The difference in nutrientsaccumulation between the concentrations of the growthregulators was not significant, but such difference wassignificant between GA3, NAA and GGG treatments.NaGI and Na2S04 application, in general, had adepressive effect on N, P, K and total carbohydrates.Such depression was significant as compared with thecontrol.The spraying of GA3, NAA and GGG on plants grownunder different levels of salinity did not have aprumised effect in increasing the accumulations of N,P, K and total carbohydrates. The NAA showed apromised effect in increasing the accumulation ofnutrients as compared with GA3 or GGG.3. The used growth regulators (GA3, NAA and GGG) led toenhancing flowering time as compared with the control.Flowering time was reduced consistently as the salinitylevels increased from 60, 80 to 100 meq./L. SprayingGA3, NAA and eee at lower concentrations seemed toenhance flowering time without significant differences,in plants grown under salinity.- J74 -4. Spraying okra plants with NAA at 100 ppm or eee at200 ppm increased total fruit yield per plant thanthat sprayed with GA3 or the control. The incrementin fruit yield per plant as a result of NAA or eeeapplication was due to the increase in average fruitweight since the fruit number was not considerablyincreased. The fruit total yield was not decreasedby any treatment of salt application than the control.Moreover, okra plants supplied with 60 meq./L of NaGIor 80 meq./L Na2S04 produced higher total yield thanthat of the control. The NaGL promoted average fruitweight, while, Na2S04 had a promotive effect on numberof fruits per plant.The application of GA3, NAA and GGG showed anincrease in total fruit yield per plant grown undersalinity levels and sources with the exception of thatgrown under Na2S04 which did not response to GA3 application.As regard to the number of fruits per plant, itwas found that, GA3 at 50 ppm and NAA at 100 ppm increasedthe number of fruits in plants grown under 80 meq./L ofeither salts. The Gee application with its two concentrationsdid not show any considerable effect on increasingnumber of fruits per plant that grown under salinitystress.The GA3 improved average fruit weight in plantsgrown at 60, 80 and 100 meq./L of NaCI. Negligibleresponse of GA3 on the effect of Na2S04 was noticedwith respect to the average fruit weight. whereas, NAAand CCC at used concentrations improved average fruitweight in those plants supplied with salinity solutions.from the preceeding results of the four experimentswe came up to the cDnclusion with respect to fruit yieldcharac te rist ics that:1. P-application had no effect on fruit yield and itscomponents as compa red with the cont rol. Whe reas, Kat the highest level (48 kg K2o/fed.) led to incrementin fruit yield and its components especially averagefruit weight. No significant differences in averagefruit weight, number of fruits, fruit yield per plantas well as fruit yield per feddan were detected. Theuse of ° kg p20s/fed. within 48 kg K20/fed. led toimprovement in fruit yield and its components andincrement in nitrogen and potassium contents in fruits.2. The introduced cultivars (White velvet, Golden Coastand Clemson Spineless) surpassed local ones (Baladyand Eskandarani) in fruit yield and its components aswell as nut rients accumulation in fruits. The firstplanting date (March, 20th) followed by secondplanting date (April, 5th) led to impreve”ent in fruityield characteristics. The White Velvet and Goldencoast surpassed the other cultivars in fruit yieldwhen planting was done in the first plan~ing date.3. Cultivar under study differed in growth, chemicalcomposition, time of flowering and fruit yield perplant as a result of sodium chloride and sulphateapplication. The cv Clemson Sp~eless surpassedother cultivars in fruit yield especially at 100 meq./Lfor each of the two salts.4. The cv. Balady responsed to growth regulatorsespecially NAA and CCC in increasing fruit yield perplant that grown under salinity stress. GA3 had noeffect on plants irrigated with sodium sulphate solution.