Varietal Response To Some Agricultural Treatments On Onion:

Kamal Gaber Abd Ei-latif

three field groups of experiments were carried out at the Farm of Nubaria Research Station, Agricultural Research Center near North of Tahrir Region, during 1995/96 and 1996/97 winter growing seasons. Each group of experirrlents was consisted ofthree triats which were performed in each season of this work. Such experiments were as follows : A) Effect of sulphur and nitrogen, phosphorus and potassiumfertilizers levels on vegetative growth, yield and its components, storageability and of onion bulbs during storage : A split plot design with three replicates was used, where four rates of sulphur were applied, as soil application, before transplantingin the main plots, at the rates of 0, 100,200 and 300 kg/fed. The N, Pand K-fertilizers were also added as soil application at three differentlevels. They were randomly distributed in the sub-plots at the levels of45, 90 and 135 kg N/fed., 30, 60 and 90 kg P20s/fed. and 24, 48 and72 kg K20/fed. In other words the three used N, P and K-fertilizerslevels were (45, 30 and 24), (90, 60 and 48) and (135, 90 and 72 kg)N, P20s and K20 per feddan, respectivelyCollected data : The data collected in this work were related to the haracters of vegetative growth, yield and its components, storageability andkeeping quality during storage. The obtained results are summarizedas follows : 1- Vegetative growth parameters : Some vegetative growth parameters such as plant, blades andbulb length, plant, blades and bulb weight and leaves number per plantwere significantly affected by sulphur and N, P and K-fertilizers doseswhere such characters were significantly affected by both Ofthe sedfactors of this study (sulphur rate and N, P and K-fertilizer level). Thehighest used rate of sulphur (300 kg/feddan) in combination with thehighest applied level of 1’1,P and K fertilizers resulted in the highestvalues of most studied vegetative growth characters of onion plantduring both seasons of this work.In other words, it may be concluded that the vegetative growthparameters gave higher values by soil application of sulphur at thehighest used rate (300 kg/fed.) and N, P and K-fertilizers at the highestadded level (135 kg N, 90 kg P20S + 72 kg K20/fed.).2- Bulb yield and its components:Respecting bulb yield and its components parameters as totaland marketable bulbs yield, percentages of both bolters and doublebulbs as well as average weight of bulb, obtained data show that suchcharacters were significantly affected by used both studied factors(sulphur rate and nitrogen, phosphorus and potassium fertilizerslevels) and their interaction in both seasons of this work. It has beenfound, in general, that using the highest applied rate of sulphur (300kg/fed.) in combination with the highest used level ofN, P and Kfertilizers(135 kg N, 90 kg P20s + 72 kg K20/fed.) resulted in thehighest values of studied yield and its components parameters.Hence, it is generally advisable that application of 300 kg/fed.sulphur at time of soil preparation and fertilizing onion plants with135 kg N + 90 kg P20S + n kg K20/fed. leads to obtain the highestonion bulb yield either as total or marketable yield as well as averagebulb weight without clear effect on double and bolters bulbs whereincrements in this respect did not affect bulb marketable yield.3- Storageability paramters:The percentages of sprouting, rotting, total weight loss andmarketable onion bulbs after storage for a period of 5 months undernormal room conditions (28.51±2°C) were significantly affected by allused treatments of sulphur soil application rate and N, P and Kfertilization level.It is generally found that increasing sulphur application rate upto the highest used one (3(10 kg/fed.) in combination with the highestapplied level of N, P and K-fertilizer (135 kg N, 90 kg P20s + 72 kgK20/fed.) significantly improved the storageability of onion bulbsafter five months of storage period showing that such treatmentdecreased the percentage of sprouting, rotting and total weight lossand increased the percentage of marketable onion bulbs at the end ofstorage period compared with other treatments.B) Effect of planting date and cultivar on vegetative growth, bulbyield and its components as well as storageability of onion:A split plot within complete randomized blocks (CRB) designwith four replicates was used in this work where three transplantingdates in combination with three cultivars were studied. The plantingdates i.e., early in December 5th, medium in December zs” and late inJanuary 15th were situated in the main plots. Moreover, the three testedcvs. i.e., Giza 20 and Giza 6-Mohassen and Composite El-Bostan cvs.were randomly distributed at sub-plots.The collected data regarding the characters of vegetativegrowth, bulb yield and its components as well as storageability wereas follows : 1- Plant vegetative growth parameters : The length of either bulb, blades or whole plant, the weight ofwhole plant, blades or bulb, leaves number per plant and T.S.S.%were significantly affected with transplanting date in all seasonswhere early planting on December 5th resulted in more vigorus growththan other tested planting dates.Regarding the effect of cultivar on some characters hereabove,significant variations were detected in both seasons of this work whereplants of Giza 20 and Composite cvs. were of significantly highervalues than those of Giza 6-Mohassen in this respect.With respect to the interaction between transplanting date andcultivar, the plant vegetative growth parameters were significantlyaffected during the two successive seasons of this work.As a general conclusion, early transplanting (December 5th) ofthe cultivars Giza 20 and that of composite produced plants of thehighest growth parameters tnan other tested treatments.2- Bulb yield parameters:The total and marketable bulbs yield as well as average bulbweight were significantly affected with transplanting date and cultivarwhere plants grown early on December Sst of the cultivar Giza 20 cv.produced the highest total and marketable yield as well as the heaviestaverage bulb weight compared with other combinations betweenplanting date and cultivar in both the two seasons of this work.Generally, it may be advisable to transplant the Oniontransplants of Giza 20 or Composite cvs. on early planting date(December 5th) other than growing transplants of Giza 6-Mohassen cv.on the late planting date (January 15th) under similar conditions of thisexperimental work to obtain higher total and marketable bulbls yieldoflarge onion bulbs.3- Some bulbs quality parameters:Concerning the effect of transplanting date on some bulbsquality, i.e., shape index, number of complete rings/bulb, number ofgrowing centers/bulb, thickness of complete rings/bulb, doublebulbs%, bolting bulbs % and T.S.S. %, significant differences wereresulted where all such studied characters showed higher values withthe early planting (December 5’h) than those of medium planting date(December 25th) than those of the late one (January 15th).Regarding the effect of cultivar on the studied bulbs qualitycharacters, obtained results show that each of Giza 20 and Compositecvs. were of higher values of bulbs quality parameters than those ofGiza 6-Mohassen cv.Respecting the effect of interaction between transplanting dateand cultivar on some bulb quality characters, significant differenceswere detected where the transplants of each of Giza 20 and Compositecvs. when grown early on December 5th resulted in the highest valuesof studied characters compared with other studied treatments duringboth seasons of this work.Under similar conditions of this work, it may be recommendedto grow either Giza 20 or Composite cvs. of onion in the earliest usedplanting date, i.e., December 5th to obtain bulbs of better quality thanthose of Giza 6-Mohassen cv. grown in the other used planting dates.4- Storageability parameters:The collected data showing the storageability parameters such aspercentages of sprouting, rotting, total weight loss and marketableyield reveal that such parameters were significantly affected withtransplanting date in the two seasons of this work. Respecting effect of cultivar on the studied bulb qualitycharacters, the same results show that bulbs of Giza 20 and Compositecvs. were of better storageability than those of Giza 6-Mohassen cv.Concerning effect of the interaction between planting date andcultivar, in this respect, significant effects were resulted where bulbsof Giza 20 or those of composite cvs. when they were grown on themedium planting date (December 25th) showed the best storage qualityparameters where the lowest percentage of bulb sprouting, rotting andtotal weight loss and the highest marketable yield percentgae wererecorded. Hence, it may be concluded that, under similar conditions of thiswork, planting Giza 20 or composite cvs. on December zo” isprefairable for getting onico bulbs of better keeping quality more thanthose of Giza 6-Mohassen cv. at other used planting dates. However,transplanting on the early planting date (December 5th) is stell prefairable in general fix its superiority in producing highermarketable yield than other tested planting dates.C) Effect of some cultivars and transplants size on yield and quality of onion bulbs production :A split plot design with three replicates was used, where the twostudied cultivars, i.e., Giza 20 and Giza 6-Mohassen were situated inthe main plots while the three studied transplants sizes, i.e., large «16 mm), medium (8-16 mm) and small (> 8 mm) were assigned in the sub-plots. The obtained results are summarized as follows : 1- Total bulbs yield (ton/fed.): Data showing the total bulb yield of the studied two cvs. ofonion as affected by the three tested different sizes of seedlings inboth growing seasons of this work, reveal that Giza 20 cv. gave highertotal bulb yield than that of Giza 6-Mohassen cv.With regard to the effect of size of seedling on total bulb yield,the same obtained results show that significant variations weredetected during both growing seasons of this work where largeseedlings « 16 mm) produced the highest bulbs yield of onion in thisrespect.Concerning the effect of interaction between the studied twofactors (cultivarand seedling size), obtained results show that totalbulb yield was significantly affected in this respect where the largestused transplants « 16 mrr) of the Giza 20 cv. produced plants of thehighest total bulb yield (ton/fed.).2- Marketable bulbs yield (ton/fed.):Obtained results in this respect, show that the marketable bulbsyield was significantly affected by used cultivars, size of seedlingsand their interaction.Respecting the effect of either used cultivar, transplant size or the interaction between the tested cultivars and seedling size on marketable bulb yield, similar results to those of the total bulb yield (ton/fed.) were reported where the highest values in this respect were those of the largest used seedlings of the cultivar Giza 20.3-Average bulb weight (g):The obtained results showing the average of bulb weight, asaffected by different used seedlings size, cultivar and their interaction,revealed that bulbs produced from plants of Giza 20 cultivar grown bythe largest used transplants were of the heaviest average weight.4- Percentage of doubling (split bulbs):The doubling percentage in onion bulbs as affected by seedlingsize and cultivar as well as their interaction showed the highest valueswere obtained with the largest used seedlings « 16 mm) of Giza 6-Mohassen cv. Hence, using the small sized transplants (> 8 mm) of thecultivar Giza 20 is prefairable to produce onion bulbs of the lowestdoubling percentage.S- Percentage of bolters (premature flowering):The obtained results, showing the effect of each of cultivar,seedling size and their interaction on the percentage of onion bulbsboltering revealed that small transplants (> 8 mm) of the cultivar Giza20 produced bulbs of the lowest percentage of bolters.Generally, it may be concluded that using transplants of largesize « 16 mm) of Giza 20 cv. is prefaired than those of either smallmedium or large size transplants of Giza 6-Mohassencv. and also thanthe small or medium sized transplants of, Giza 20 cv. This is due to itshigher total and marketable bulb yield (ton/fed.) as well as higher