Comparing Four Different Squash Hybrids on Growing Degree Days (GDD) Bases

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This investigation was conducted during two seasons (2012 and 2013) at the Central Laboratory for Agricultural Climate (CLAC) Dokki, Agricultural Research Center (ARC), Giza, Egypt. The experiment aimed to study the effect of four different sowing
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   Researcher 2014;6(7) http://www.sciencepub.net/researcher  97 Comparing Four Different Squash Hybrids on Growing Degree Days (GDD) Bases Fatma S. Moursy, I. I. Sadek, M. A. M. Heggi and A. A. Farag Central laboratory for Agricultural Climate (CLAC), Agricultural Research Center, Giza- Egypt Abstract: This investigation was conducted during two seasons (2012 and 2013) at the Central Laboratory for Agricultural Climate (CLAC) Dokki, Agricultural Research Center (ARC), Giza, Egypt. The experiment aimed to study the effect of four different sowing date (March 23 rd , April 2 nd , April 12 th  and April 22 nd ) and four Squash hybrids ( Cucurbita pepo  L. Eskandarany, Marzouka, Revera and Rosina). The experimental design was a split-plot with four replications. Squash plants ( Cucurbita pepo  L.) were planted in clay soil. Number of leaves and plant fresh and dry weights were measured after 90 days from each sowing date. Mineral nutrient contents (nitrogen, phosphor and potassium) were analyzed in the mature leaves after 60 days from each sowing date. In addition, total yield (kg/plant) and fruits (number/plant) were measured for each hybrid in each sowing date. The accumulative growing degree days (GDD) for each hybrid was calculated for different phenological stages depending on planting date and  both maximum and minimum air temperature at Dokki site. Results confirmed that, using different sowing dates for the four squash hybrids had an effect on vegetative growth parameters (Number of leaves, Plant fresh weight and Plant dry weight), nutrients content on leaves (N, P and K) and yield. In addition, highest values of vegetative growth parameters, nutrient contents and total yield and accumulated GDD were obtained from the second sowing date and Eskandarany hybrid. Economic evaluation indicated that the second sowing date and Eskandarany hybrid had highest net return (L.E)/feddan. Finally, a polynomial relationship between the total accumulative GDD and the total yield for four the hybrids were found (determination of coefficient) R  2 . [Fatma S. Moursy, I. I. Sadek, M. A. M. Heggi and A. A. Farag. Comparing Four Different Squash Hybrids on Growing Degree Days (GDD) Bases.  Researcher   2014;6(7):97-111]. (ISSN: 1553-9865). http://www.sciencepub.net/researcher . 12 Key word:  Squash hybrids - Sowing date - growing degree days (GDD) -vegetative growth – total yield. 1. Introduction: Environmental variables are the key factor affecting plant growth, crop growth, development and yield through agronomic, physiological and qualitative functions of the crop plant (Kaleem et al  ., 2009; Kaleem et al  ., 2010a; Kaleem et al  ., 2011). Air temperature is among the most important environmental factors that control plant development, growth and yield. It is a major environmental factor that determines the rate of plant growth and development. All biological processes respond to temperature, and all responses can be summarized in terms of three cardinal temperatures, namely the base or minimum (T min ), the optimum (T opt ), and the maximum (T max ) temperatures. The nature of the response to temperature between these cardinal points, which is important for calculating the phenology, adaptation and yield of various crops (Shaykewich, 1995). The most common temperature index used to estimate plant development is growing degree days (GDD), or heat unit (HU). The accumulation of GDD determines time of developmental events, maturity of the crop and yield. A linear relationship between GDD and the rate of plant development was found and reported by Lu et al  ., 2001. Crop display and yield characteristics are influenced by environmental disparity (Kaleem et al  ., 2010b). Combined effects of environmental factors not only modify plant phenology, but also cause many  physiological and qualitative changes. Differences of yield attributes in varying seasons might be due to the different climatic conditions that are based on temperature prevailing during the crop life cycle (Kll and Altunbay, 2005). Genotypes behave differently under different environmental conditions (Qadir et al  ., 2007). Most crop species are adapted to particular set of temperature, as temperature is a major environmental factor influencing their distribution (Atkinson and Porter, 1996). Temperature variations in the field can  be created by planting crops at different dates in the season, thus crop will grow at different temperature, sunshine and relative humidity. Cucurbits play a significant role in human nutrition. Cucurbits crops constitute a major portion of vegetable production and are grown in different regions in Egypt. Squash ranked the second among the popular cucurbits  preceded by watermelon (Yousef et al  , 2013). In Cucurbitaceae, temperature is the major factor in determining the time of pollen shed, flower opening and pollination and growth rate, which in turn could influence yield and quality (Bielinski et al  ., 2008). Different squash hybrids require different total number of cumulative degree-days or growing degree days for growth, development and maturity.   Researcher 2014;6(7) http://www.sciencepub.net/researcher  98 All physiological and morphological developments occurring in plant are markedly influenced by temperature. Different planting dates might cause different environmental conditions from emergence to harvest. This study mainly aimed to: 1-   Investigate the relationship between growing degree days and different phenological stages and yield of squash hybrids. 2-   Determin the adaptation ability of the four tested squash hybrids. 3-   Calculate the necessary demands of growing degree days for each of studied squash hybrids. 2. Material & Method The investigation was carried out in seasons 2012 and 2013 at the Central Laboratory for Agricultural Climate (CLAC), Dokki, Giza. Seeds of squash hybrids were sown in four beds (forty meters each). Each bed was sown at one sowing date. Moreover, each bed was divided into four parts every  part contain one squash hybrid. Therefor, each experimental plot was 10 meter long and 1 meter wide and contain twenty plants. Studied factors: Two factors were studied; first factor was the four sowing dates whereas; seeds were sown in (March 23 rd , April 2 nd , April 12 and April 22 nd ). The second factor was the four squash hybrids ( Cucurbita  pepo  L., Eskandarany, Marzouka, Rosina and Revera).  Measurements: Growth parameters Plant samples from each experimental plot were taken after 90 days from every sowing date to determine growth parameters as follows: 1- Number of leaves: total number of complete mature leaves per plant was counted. 2- Fresh and dry weights per plant: plant fresh weight was taken after 90 days from each sowing date. Plants were air dried and then put into the oven at 105 o C for 10 hours and weighted for dry weight. Chemical analysis:  Three plants from each hybrid, at different sowing date were randomly taken for the mineral nutrients (nitrogen, phosphor and potassium) analysis in the mature leaves after 60 days from each sowing date according to ADAS/MAFF (1987). For mineral analysis, wet distraction was performed according to FAO SOILS BULLETIN. 1- Nitrogen: total nitrogen was determined using Kjeldahl method according to the procedure described  by FAO (1980). 2- Phosphorous%: phosphorous concentration in acid digested was determined by colorimeter method (ammonium molybdate) using spectrophotometer according to Watanabe and Olsen (1965) and the data was calculated as percentage. 3- Potassium%: potassium content was determined  photo-metrically using Flame photometer as described  by Chapman and Pratt, (1961) and the data was calculated as percentage. Yield measurements: Total yield: cumulative total fruit weight (kg/plant) and fruits number/plant were recorded and calculated for each hybrid in each sowing date. Climatic measurements: Daily maximum and minimum air temperatures were collected from Dokki weather station during the period from March to June during 2012 and 2013 seasons. Growing degree days (GDD) calculation: Phenological stages as well as number of days  between each phenological stage were recorded and GDD was also calculated for every stage using climatology data with the following equation. Where T max  = daily maximum air temperature T min  = daily minimum air temperature T  b  = base temperature Maximum air temperatures were adjusted to upper temperature (32 o C). In case of T max  exceed upper threshold temperature (T ut ) then T max  equal T ut . The Base temperature for squash development is 8°C according to (Maynard and Hochmuth, 2007).  Experimental design & statistical analysis The experiment was designed using split plot design with four replicates. The main plots and subplots were assigned to squash hybrids (A) and sowing dates (B), respectively. The obtained data were statistically analyzed using the analysis of variance method according to Snedicor and Cochran (1980). Duncan's multiple range test at 5% level of probability was used to compare means of the treatments. Squash plants were irrigated by using drippers of 4 l/hr capacity. The chemical fertilizers were injected within irrigation water system. The row-to-row distance was maintained at 75 cm and plant-to- plant distance at 50 cm.  Economic evaluation  Finally, economic indicators were used to  provide economic evaluation for this experiment. 3. Results: 1-   Climatic circumstances The field experiment was conducted during the period from March 23 rd  to   July 16 th  2012 and from March 23 rd to   July 10 th  2013. Both growing seasons were characterized by the high daily air temperatures through the period of the two studied seasons (Figures   Researcher 2014;6(7) http://www.sciencepub.net/researcher  99 1 and 2). The highest recorded maximum and minimum air temperature were “42 and 26.2°C” and “43.8 and 26°C during seasons 2012 and 2013, respectively. However, the lowest recorded maximum and minimum air temperature were “22 and 9.8°C” and “18 and 11.5°C” during 2012 and 2013, respectively. The averages maximum and minimum air temperatures for the four tested sowing dates growing  period in season 2012 were “32.6 and 18.9 °C”, “34 and 20.4 °C”, “34.5 and 20.9 °C” and “35 and 21.5 °C” during the first, second, third and fourth sowing dates, respectively. While through 2013 season they were “32.4 and 18.4 °C”, “33.6 and 19.8 °C”, “34.1 and 20.2 °C” and “35.1 and 21 °C”, respectively. From the overall illustrated climatic circumstances, it’s clear that such conditions will reflect directly on the calculated GDD, whereas, the highest calculated GDD (21 GDD/day) was found at the same day with the highest maximum and minimum air temperature during both studied seasons. The same conclusion was found regarding the lowest calculated GDD “8 and 9.7 GDD/day”, which were observed at the days characterized by the lowest recorded maximum and minimum air temperatures at 2012 and 2013 seasons, respectively. Averages calculated GDD/day during the  period of the four sowing dates were 16.6, 17.8, 18.2 and 18.6, respectively during 2012. And it recorded 16.2, 17.2, 17.6 and 18.2, during season 2013, respectively. 2-Vegetative growth: 2-1 GDD& days to emergence It’s concluded from data in Table (1) that, different sowing dates and hybrids as well as the interaction between them significantly affected both number of days and accumulative heat units from sowing to emergence. Focusing on effect of different sowing dates, first sowing date (March 23 rd ) had the longest period to emergence in both studied seasons. While, the third and fourth sowing dates (April 12 and April 22 nd ) recorded the shortest period to emergence during the 2012 and 2013 season. In addition, accumulated growing degree days (GDD) from sowing date to the complete emergence presented a significant difference  because of the different sowing dates. The highest significant GDD was found in the third sowing date (April 12) during the first season and was found in the first sowing date (March 23 rd ) during the second season. Contrary, the lowest significant GDD was obtained in first (March 23 rd ) and fourth (April 22 nd ) sowing dates during seasons 2012 and 2013, respectively. The mentioned differences in GDD during those period were a direct results for the different in air temperature existed during this times. Regarding the effect of squash hybrids, Marzouka significantly recorded the longest period to emergence in both studied seasons. However, Revera and Rozena recorded the shortest periods to emergence in both studied seasons. Also, the same trend of results was found in GDD. The highest GDD from sowing to emergence was required for Marzouka compared to Revera and Rozena, whereas they required a less GDD from sowing to emergence. Interaction between studied squash hybrids and tested sowing dates reflect a clear significant difference in both number of days. Interaction  between Marzouka and first sowing date recorded the longest period to emergence during seasons 2012 and 2013. While the interaction between Marzouka and first sowing date and interaction between Marzouka and second sowing dates significantly recorded the highest GDD in seasons 2012 and 2013, respectively, due to different climatic circumstances in the first and second seasons according to Kll and Altunbay, 2005. Table (1): Effect of different sowing dates and squash hybrids on number of days and accumulative GDD to emergence. Days to Emergence Mean First season Mean Second season March 23 rd  April 3 rd  April 12 April 22 nd  March 23 rd  April 3 rd  April 12 April 22 nd  Eskandarane 6.0 ab 4.0 b 4.0 b 4.0 b 4.5 B 5.0 ab 4.0 bc 4.0 bc 3.0 c 4.0 A Marzoka 7.0 a 6.0 ab 5.0 ab 5.0 ab 5.8 A 6.0 a 5.0 ab 5.0 ab 4.0 bc 5.0 A Revera 5.0 ab 4.0 b 4.0 b 4.0 b 4.3 B 5.0 ab 4.0 bc 4.0 bc 3.0 c 4.0 A Rozina 5.0 ab 4.0 b 4.0 b 4.0 b 4.3 B 5.0 ab 4.0 bc 4.0 bc 3.0 c 4.0 A Mean 5.8 A 4.5 AB 4.3 B 4.3 B 5.3 A 4.3AB 4.3AB 3.3 B GDD to Emergence Eskandarane 55.0 d 55.0 d 67.0bc 56.5 d 58.4 B 56.0cd 49.5de 48.5 e 35.0 f 47.3 B Marzoka 64.0 c 89.5 a 84.5 a 73.5 b 77.9 A 70.5 a 66.5ab 59.5bc 44.0 e 60.1A Revera 46.0 e 55.0 d 67.0bc 56.5 d 56.1 B 56.0cd 49.5de 48.5 e 35.0 f 47.3 B Rozina 46.0 e 55.0 d 67.0bc 56.5 d 56.1 B 56.0cd 49.5de 48.5 e 35.0 f 47.3 B Mean 52.8C 63.6B 71.4A 60.8B 59.6 A 53.8 B 51.3 B 37.3C   Researcher 2014;6(7) http://www.sciencepub.net/researcher  100 Figure 1: The maximum and the minimum air temperature and the accumulative growing degree days (GDD) for the four sowing dates growing seasons (2012).   0510152025303540    0   3   /   0   4  -   1   2   /   0   4   1   3   /   0   4  -   2   2   /   0   4   2   3   /   0   4  -   0   2   /   0   5   0   3   /   0   5  -   1   2   /   0   5   1   3   /   0   5  -   2   2   /   0   5   2   3   /   0   5  -   0   1   /   0   6   0   2   /   0   6  -   1   1   /   0   6   1   2   /   0   6  -   2   1   /   0   6   2   2   /   0   6  -   0   1   /   0   7   0   2   /   0   7  -   1   1   /   0   7   1   2   /   0   7  -   1   3   /   0   7 Second sowing date The maximim and minimum air temperature and the accumulative GDD during the second sowing date 2012 seasonTmaxTminGDD0510152025303540    1   2   /   0   4  -   2   1   /   0   4   2   2   /   0   4  -   0   1   /   0   5   0   2   /   0   5  -   1   1   /   0   5   1   2   /   0   5  -   2   1   /   0   5   2   2   /   0   5  -   3   1   /   0   5   0   1   /   0   6  -   1   0   /   0   6   1   1   /   0   6  -   2   0   /   0   6   2   1   /   0   5  -   3   0   /   0   6   0   1   /   0   7  -   1   0   /   0   7   1   1   /   0   7  -   1   6   /   0   7 Third sowing dateThe maximim and the minimum air temperature and the accumulative GDD during third sowing date 2012 season TmaxTminGDD0510152025303540    2   2   /   0   4  -   0   1   /   0   5   0   2   /   0   5  -   1   1   /   0   5   1   2   /   0   5  -   2   1   /   0   5   2   2   /   0   5  -   3   1   /   0   5   0   1   /   0   6  -   1   0   /   0   6   1   1   /   0   6  -   2   0   /   0   6   2   1   /   0   6  -   3   0   /   0   6   0   1   /   0   7  -   1   0   /   0   7   1   1   /   0   7  -   1   5   /   0   7 Fourth sowing dateThe maximim and the minimum air temperature and theaccumulative GDD during fourth sowing date 2012 season TmaxTminGDD   Researcher 2014;6(7) http://www.sciencepub.net/researcher  101 Figure 2: The maximum and the minimum air temperature and the accumulative growing degree days (GDD) for the four sowing dates growing seasons (2013).   010203040    2   3   /   3  -   0   1   /   0   4   0   2   /   0   4  -   1   1   /   0   4   1   2   /   0   4  -   2   1   /   0   4   2   2   /   0   4  -   0   1   /   0   5   0   2   /   0   5  -   1   1   /   0   5   1   2   /   0   5  -   2   1   /   0   5   2   2   /   0   5  -   3   1   /   0   5   0   1   /   0   6  -   1   0   /   0   6   1   1   /   0   6  -   2   1   /   0   6 First sowing dateThe maximim and the minimum air temperature and the accumulative GDD during second sowing date 2013 season TmaxTminGDD0102030    0   3   /   0   4  -   1   2   /   0   4   1   3   /   0   4  -   2   2   /   0   4   2   3   /   0   4  -   0   2   /   0   5   0   3   /   0   5  -   1   2   /   0   5   1   3   /   0   5  -   2   2   /   0   5   2   3   /   0   5  -   0   1   /   0   6   0   2   /   0   6  -   1   1   /   0   6   1   2   /   0   6  -   2   1   /   0   6   2   2   /   0   6  -   0   1   /   0   7   0   2   /   0   7  -   1   0   /   0   7 Second sowing date The maximim and the minimum air temperature and the accumulative GDD during second sowing date 2013 season TmaxTminGDD010203040    1   2   /   0   4  -   2   1   /   0   4   2   2   /   0   4  -   0   1   /   0   5   0   2   /   0   5  -   1   1   /   0   5   1   2   /   0   5  -   2   1   /   0   5   2   2   /   0   5  -   3   1   /   0   5   0   1   /   0   6  -   1   0   /   0   6   1   1   /   0   6  -   2   0   /   0   6   2   1   /   0   5  -   3   0   /   0   6   0   1   /   0   7  -   0   9   /   0   7 Third sowing date The maximim and the minimum air temperature and the accumulative GDD during third sowing date 2013 season TmaxTminGDD010203040    2   2   /   0   4  -   0   1   /   0   5   0   2   /   0   5  -   1   1   /   0   5   1   2   /   0   5  -   2   1   /   0   5   2   2   /   0   5  -   3   1   /   0   5   0   1   /   0   6  -   1   0   /   0   6   1   1   /   0   6  -   2   0   /   0   6   2   1   /   0   6  -   3   0   /   0   6   0   1   /   0   7  -   0   8   /   0   7 Fourth sowing dateThe maximim and the minimum air temperature and the accumulative GDD during fourth sowing date 2013 season TmaxTminGDD
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