|The effects of different cattle manure levels and branch management methods on
organic production of Cucurbita pepo L.
M. Jahan, A. Koocheki, M. Nassiri, F. Dehghanipur11
To study the effects of different manure levels and two branch management methods on organic production of Schneider squash, a field experiment was conducted during years 2005 and 2006. Treatments were four manure levels (10, 15, 20, 25 tons.ha-1) and two branch management methods (with and without wood pole), which were allocated to main plots and subplots, respectively. Results showed that crop performance in branch management method without wood pole was better than branch management method with wood pole. Results showed that in the first year, manure level had significant effect on fruit and seed yields. However, these traits were not significantly affected by manure levels in the second year. For both years, there were no differences in seed numbers due to manure levels. Seed oil content was slightly increased when manure level was increased from 10 to 25 tons.ha-1.
Keywords: Schneider squash, manure, seed oil, yield, organic production.
In recent years safety and health of food has becoming a major concern due to over use of chemicals for food production and its negative impacts on human health and environment (Gliessman 1998; Pimentel 2005). For this reason, cultivation of medicinal plants and other food plants with medicinal properties have been expanded (Berenyi 1998). Cucurbita pepo is an important oil seed plant which is used in food and also in cosmetics and health items (Aruyi et al. 2000; Younis & Al-Shihry 2000; Bombardelli et al. 1997; Murkovich et al. 1996). Murkovich et al. (1996) worked on hundred lines of this species and found 39.5-56.5 percent oil and 21-67.4 percent linoleic acid content. Aruyi et al. (2000) reported that the range of oleic and linoleic acids in the seeds were 75.98-81.84 and 12.1-16.54 percent, respectively. The purpose of this experiment was to study the effects of different manure levels and branch management methods on yield, oil and protein content of C. pepo.
Materials and methods
This study was conducted for two growing seasons of 2005-2006 in Research Farm of Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. The experiment was in the form of split plot based on randomized complete block design with three replications. Cattle manure levels of 10, 15, 20, 25 tons.ha-1 were applied in the main plots and branch management method (with and without wood pole) were allocated to the subplots. Nutrient contents of cattle manure used were 2.11, 0.73, and 1.88 % N, P and K, respectively. Original nutrient content of the soil were: 755, 42 and 465 ppm N, P and K, respectively. No chemical fertilizers or biocides were applied and weeds were controlled by hand. In the second year no soil tillage was conducted and seeds were planted on the same place and the same date as the first year. However, based on the results of the first year in which superiority of plants without wood pole was confirmed this treatment was not continued for the second year. Therefore, in this year only the effect of manure was investigated and the experiment was analyzed with levels of manure only. For analysis of variance (ANOVA) Minitab software Ver. 13 was used and means were compared with Duncan’s multiple range tests at 5% probability level.
Results and discussion
Results of combined analysis of the experimental data showed the effect of manure application on fresh fruit yield was significant; however, manure application did not affect seed dry weight and seed number (not shown). With increasing the level of cattle manure to 25 tons.ha-1 an increasing trend was observed in the yield of fresh fruit (Fig. 1). However, in the second year application of manure did not affect yield. Averaged over two years, also an increasing trend in fruit yield was observed from 10 to 20 tons.ha-1 cattle manure but significant difference was observed between 10 and 15 tons.ha-1.
Fig. 1. Effect of cattle manure levels on C. pepo fresh fruit yield. Similar letters indicate no significant differences between means within a year (p<0.05).
In general, the effect of cattle manure level was somehow inconsistent and a reduction of yield at 20 tons.ha-1 seems to be unusual. However, it may be postulated that effect of cattle manure on this species is achieved up to 20 tons.ha-1 and further increase may have had a detrimental effect possibly due to plants die off. It also could be assumed that higher levels of cattle manure might have caused water to be stored in the root zone and hence spread of root pathogens. Visual investigation showed die off of more plants at the highest manure level (25 tons.ha-1) which could have been associated with this effect. There are evidences (Bombardelli et al. 1997; Khorrami Vafa, 2006) which indicate that a well drained soil is suitable for this species. This could be an indication of sensitivity of plants to high level of water in the root zone. On the other hand, it has also reported (Aruyi et al. 2000) that application of high level of nitrogen fertilizers have caused fresh vegetative growth and hence low yield of fruit. Therefore, low yield at 25 tons.ha-1 cattle manure could be associated with higher water level in the root area and also availability of more nitrogen which changes the proportion of vegetative to generative growth.
Figure 2 shows that with increasing cattle manure level from 10 to 20 tons.ha-1 in first year, seed yield was increased but there was no further increase by increasing the level of manure to 25 tons.ha-1. However, in the second year there was no significant difference between seed yields.
Fig. 2. Interaction between cattle manure levels and year of experiment on C. pepo seed yield. Means that followe the same letters do not differ significantly (p<0.05).
By comparing Figures 1 and 2 it appeares that the trends of change in fruit and seed yields are somehow similar. In general, the response of both components to cattle manure was higher in the second year compared to the first year. This is not unusual because more nutrients are released in the second year (Kuepper 2000). However, lack of response to fertilizer levels seems unclear. In other words, the reason why there was no difference between fruit or seed yield at 10 tons.ha-1 and other manure level is unusual.
With increasing the amount of manure, oil percent showed a decreasing trend (Fig. 3). This decrease was five percent unit from application of 10 tons.ha-1 of cattle manure to 25 tons.ha-1. This has also been confirmed elsewhere (Aruyi et al. 2000). Also effect of cattle manure on protein content was negligible, an increase of one percent unit was observed from application of 10-25 tons.ha-1 (Fig. 4). In a general trend, nitrogen fertilizer has been reported to increase protein content (Levitte 1980; Khorrami Vafa 2006).
Fig. 3. Effect of cattle manure levels on C. pepo seed oil content
Fig. 4. Effect of cattle manure levels on C. pepo seed protein content
Effect of cattle manure on fruit and seed yield are almost similar and with increasing the rate of cattle manure up to 20 tons.ha-1 an increasing trend was observed but further increase in cattle manure either did not change the yield or slight reduction was observed. Therefore, an optimum amount of manure seems to be 20 tons.ha-1. The effect of cattle manure, as expected, was higher in the second year than in the first year and this was more pronounced for seed yield compared to the fresh fruit yield.
Aruyi, H., Omid-Beigi, R. & Kashi, A. (2000): Effect of nitrogen levels on some characteristics of Cucurbita pepo. Journal of Pajuhesh and Sazandegi. 48:4:9.
Berenyi B. (1998): Introduction of new species of plants to Hungarian agriculture. In: 2nd Conference on Progress in Plant Sciences from Plant Breeding to Growth Regulation, 15-17 June 1998, Mosonmagyarovar, Hungary
Bombardelli, E., & Morazzoni, P. (1997): Cucurbita pepo L. Fitoterapia. Vol. LXVIII (4):291:302.
Gliessman, S. R. (1998): Agroecology: Ecological Processes in Sustainable Agriculture. CRC Press. ISBN: 1-57504-043-3
FKhorrami-Vafa, M. (2006): Ecological study of corn (Zea mays L.) and cucurbita pepo L. intercropping. Ph. D. Thesis. Faculty of Agriculture, Tabriz University, Iran.
Kuepper, G. (2000): Manure for organic crop production. ATTRA, Fayetteville, AR 72702. Available online (July 2004) at: www.attra.org/attra-pub/manure.htm
Levitte, J. (1980): Response of plants to environmental stresses. 2nd edition. Academic Press. New York, USA.
Murkovic, M., Hillebrand, A. Winker, H. & Pfannhauser, W. (1996): Variability of vitamin E content in pumpkin seeds (Cucurbita pepo L.). Z. Lebensm Unters. Forsch. 202:275:278.
Pimentel, D., Hepperly, P. Hanson, J. Douds, D. & Seidel, R. (2005): Environmental, Energetic, and Economic Comparisons of Organic and Conventional Farming Systems. BioScience. 55 (7):573:582.
Younis, Y. M. H., & Al-Shihry, S. S. (2000): African Cucurbita pepo L.: properties of seed and variability in fatty acid composition of seed oil. Phytochemistry. 54:71:75.