تأثير الأثيفون والبورون في نمو وحاصل تركيبين وراثيين من قرع الكوسة

The Effect of ethephon and boron on growth, and yield of two summer squash genotypes

A pot experiment was carried out inside a lath house belonging to the Department of Horticulture and Landscape, College of Agriculture Kerbala university during spring and fall seasons of 2016. Experiments started on 10^th March , 2016 and 6^th September,2016 for spring and fall seasons respectively in order to study the effect of ethephon and boron on the growth, and the yield of two genotypes of summer squash.

Factorial experiment within Completely Randomized Design was adopted with 3 factors (2×4×2) for genotypes of summer squash i.e. local var. Mullah Ahmed and hybrid; four concentrations of ethephon i.e.
0, 50,100 and 150 mg/L and 2 concentrations of boron i.e. 0 and
30 mg/L with 3 replicates. Three seeds were sown in each pot on the above mentioned dates thinned into one seedling and samples were taken. Plants were sprayed with ethephon of 4-5 leaf stage which corresponds to 25^th April ,2016 in the spring season and to 5^th  October ,2016 in the fall season. Boron was sprayed one week later i.e. at 6-8 leaf stage which corresponds to 2^nd, May , 2016 and to 12^th October, 2016. The plants were removed on 3^rd July 2016 and 3^rd December 2016 for spring and fall seasons respectively. At the time of experiment termination, samples were taken to determine some chemical traits, root, shoot, and flower growth and the yield. Data were subjected to the analysis of variance, means were compared using L.S.D test at 0.05 probability  level. Results could be summarized as follow:

1. There was no significant effect of genotype on the concentration and content of boron in roots, root dry weight and fruit weight during spring season, meanwhile it had a marked effect on the rest of  The hybrid was  superior in most of these characters. During fall season there    was no significant influence due to the genotype on N and P leaves concentration, and content , leaf B content, protein percentage ,and fruit weight whereas the genotype  markedly affected the other traits, where the local variety was mostly superior.
2. Ethephon positively affected most of studied characters, but the effective concentration, fluctuated from season to another, 150 mg/L ethephon was the effective concentration, during spring season, it was shared with 100 mg/L ethephon during fall season.
3. Apart from some traits i.e. root diameter, female flowers no. and sex ratio in both seasons, boron with 30 mg/L had a marked influence on the studied characters in terms of physiological traits, growth and yield and its components as compared with the control.
4. The interaction between genotype and ethephon caused an increase of most studied parameters . The highest values associated with the hybrid genotype at 150 mg/L, ethephon during spring season. Meanwhile the highest values were obtained from 100 and 150 mg/L, ethephon in equally proportion for the local genotype during fall season. This interaction markedly affected the number of female and male flowers. Female flowers increased in the local genotype from 12.00 flowers at 0 concentration ethephon to 16.00 flowers at 150 mg/L ethephon and from 15.5 flowers to 19.00 flowers during spring and fall seasons respectively . On the other hand, female flowers decreased in the hybrid genotype from 26.00 flowers at 0 concentration to 22.34 flowers during spring season and from 30.67 flowers  to 27.17 flowers during fall season at 150 concentration , ethephon. The opposite trend was occurred with the male flowers, where it decreased in the local genotype from 32.34 flowers to 24.34 flowers, whereas it increased in the hybrid genotype from 19.67 flowers to 22.34 flowers during spring season . The same trend occurred with the fall season, where male flowers decreased in the local from 42.84 flowers to 33.50 flowers whereas it increased in the hybrid from 24.50 flowers to 29.00 flowers
5. The Interaction between genotype and boron was positive. Apart from some cases, foliar application of boron at 30 mg/L increased most studied characteristics. It is worth mentioning that the percentage increase of female flowers no. in the local was 30.81% and 18.84% during both seasons respectively. On the other hand, boron treatment decreased male flowers no.in the hybrid by 12.93% and 9.09%. for spring and fall seasons respectively
6. The interaction between ethephon and boron significantly affected most studied parameters where 150 mg/L. ethephon and 30 mg/L boron treatment was superior among other interactions. This treatment gave higher values during spring season whereas ethephon at either 100 or 150 mg/L with 30 mg/L boron treatments were equally higher during fall season. This interaction did not reveal any effect on the number of female and male flowers. Whereas it appeared a significant influence on the sex ratio during spring season only, fruit weight, fruit no and the yield where they were increased as a result of increasing ethephon from 0 to
   150 mg/L and boron from 0 to 30 mg/L.
7. The interaction between genotype, ethephon and boron significantly affected root-K concentration, leaf-N and B concentration, root N,P, K,B, content; leaf- N,K,B content; absorption rate of N,K and B transport rate of N,P, K and B, chlorophyll concentration protein percentage, free auxin, gibberellin, cytokinin , Abscisic acid, root length, root dry weight, stem length, leaves no. ,leaf area and shoot dry weight during spring season. During fall season, the following parameters were increased due to this interaction: root P and K concentration ; leaf P,K and B concentrations, leaf- P and B content; P absorption rates and transport rate , chlorophyll, carbohydrate, free auxin, cytokinin, Abscisic acid, root length and diameter, leaves no. and area, shoot dry weight and sex ratio. Other traits were not influenced by the interaction between the previous mentioned factors.