The effects of sowing date and spacing for yield of green bean (Phaseolus vulgaris L.) varieties at Jimma, Southwestern Ethiopia

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1 Sky Journal of Agricultural Research Vol. 3(9), pp , October, 2014 Available online ISSN Sky Journals Full Length Research Paper The effects of sowing date and spacing for yield of green bean (Phaseolus vulgaris L.) varieties at Jimma, Southwestern Ethiopia Essubalew Getachew 1 *, Abush Tesfaye 2 and Tewodros Mulualem 2 1 Department of Horticulture, Wolkite Uinversity College of Agriculture and Natural Resources P.O. Box 07, Wolkite, Ethiopia. 1,2 Jimma Agricultural Research Center P.O. Box 192, Jimma, Ethiopia. Accepted 9 September, 2014 Appropriate sowing dates and plant populations, along with adapted variety has paramount significance in improving the pod yield, quality and disease severity of green bean. The aim of the experiment was to determine the proper sowing date, varieties, and optimum plant spacing, and their interaction effects for better yield of green beans under Jimma condition. There were five levels of spacing; four level of sowing dates and two varieties were used and laid in randomized complete block design with three replications. The analysis of variance revealed that variety showed significant differences for total unmarketable pod yield, total number of pod per plant, dry weight of pod, dry weight of shoot and root, average individual pod weight, and pod diameter; while spacing showed significant differences for total marketable pod yield, total unmarketable pod yield, total number of pods per plant, dry weight of pods and plant height. All the studied traits showed highly significant differences for sowing dates. The interaction effect between variety and sowing date was significant for total number of pods per plant, dry weight of pods, pod length, average individual pod weight, pod diameter, plant height and leaf area while it was significant only for total number of pods per plant, dry weight of pods, and dry weight of shoot and root in the case of spacing and sowing date interaction. The highest total marketable pod yield was produced by green bean sowed on July 3 rd. The highest number of seeds per pod was observed from green bean sowed on the 18 th and 2 nd of August. Green bean spaced at 40 cm 7 cm resulted in the highest marketable pod yield. Key words: Green bean, marketable, plant spacing, sowing date, varieties. INTRODUCTION Green bean (Phaseolus vulgaris L.) is one of the most important leguminous vegetable crop in the world (Rubatzkey and Yamagucbi, 1999). The total annual production of green beans in the world reaches 6,814,403 tons from the area of 960,272 ha (FAO, 2009). About 50 and 30% of world production comes from Asia and Europe. Of these, China and Turkey produce 17% and 13% of the world production, respectively (Rubatzkey *Corresponding author. essubalewgetachew@yahoo.com. and Yamagucbi, 1999). In Ethiopia, there is no exact information as to when green bean was first introduced; however, the crop is cultivated in different major growing areas of the country. Currently, the total area coverage of green bean in Ethiopia is more than 15,379 ha with an average total production of 6,803tonnes (FAO, 2009). It has been among the most important and highly prioritized crops as a means of foreign currency earning in Ethiopia (Gezahegn and Dawit, 2006). Nowadays, it is becoming a high value commodity which has the potential for

2 Getachew et al. 175 improving the incomes and livelihoods of thousands of smallholder farmers in Ethiopia and diversifying and increasing Ethiopia s agricultural export exchange earnings (Lemma, 2003).Despite the importance of this crop, the production and productivity is constrained by different biophysical and socio-economic reasons, such as: lack of genotype screening undertaken across different climatic zones, diseases and pests infestation, high post-harvest losses and lack of cultural practices, such as appropriate sowing date and plant spacing are a few of them (Lemma, 2003;Amanullahet al., 2002). Therefore, this study was designed for determining appropriate sowing date, optimum plant spacing, varieties and their combination for better pod yield and related agronomic traits of green beans in major growing areas of Jimma zone of southwest Ethiopia. and diseases control were carried out as recommended (Lemma, 2003). Data collection Data on the pod yield and yield related agronomic traits of green bean were recorded from each plot by taking ten random sampled plants. These quantitative traits includes: total marketable and pod yield (kg ha -1 ), total unmarketable pod yield (kg ha -1 ), plant height (cm), leaf area (cm 2 ), pod length (cm), pod diameter (cm), number of seed per pod, average individual pod weight (g/pod -1 ), dry weight of shoot and root (g/plant -1 ), dry weight of pod (g/plant -1 ) and total number of pod per plant were collected. MATERIALS AND METHODS Description of the experimental site The study was conducted at Jimma University College of Agriculture and Veterinary Medicine experimental site during 2010/2011 main cropping season. The area is located at 7 0 S 42 9 N latitude, E longitudes and an elevation of 1753mabove mean sea level. The experimental site receives an average annual rainfall of 1559mm with maximum and minimum temperatures of 26.8 and 13.6 C respectively, and the average maximum and minimum relative humidity of the area are 67.5 and 37.9%, respectively. The soil of the experimental site is reddish brown clay, classified as Nitisol with ph range of 5.0 to 6.0 (BPEDORS, 2000). Experimental design and treatments Two green bean varieties, namely Melka-1 and Melka- 5,obtained from Melkassa Agricultural Research Center, were used for the study. The experiment consisted of three factors namely viz. five levels of inter-row and intrarow spacing (50 7 cm, cm, cm, 40 7 cm, cm), four levels of sowing dates (July 3 rd, July 18 th, August 2 nd, and August 17 th, 2010) and two green bean varieties (Melka-1 and Melka-5) arranged in factorial in randomized complete block design with three replications. The national recommended spacing was used as reference with some modifications. There were four rows in each plot that were spaced differently as per the respective treatments. The spacing between plots and blocks were 0.5 and 1 m respectively. The first sowing was on the 3 rd of July, 2010 and subsequent sowings for the other treatments were conducted at 15 days of interval. All field management practices like weeding; fertilizer application, insect pest Data analysis Before analysis of the data, assess the normality and meeting all assumptions for ANOVA for each trait. Analysis of Variance (ANOVA) and correlation was performed using Genstat version 11 (VSN International, 2008) with the REML variance components analysis. Mean separation was carried out using LSD (Least Significant Difference) test at 5% level of significance for traits that showed significant mean squares (Gomez and Gomez, 1984). RESULTS AND DISCUSSION Analysis of variance There was significant (P 0.05) effect of sowing date on the total marketable pod yield, total unmarketable pod yield and number of seeds per pod (kg ha -1 ) of green bean. The effect of spacing on total marketable pod yield, total unmarketable pod yield (kg ha -1 ) and leaf area (cm 2 /plant -1 ) of green bean was significant at (P 0.05). The varietal difference was found to be significant (P 0.05) for unmarketable pod yield of green bean (Table 1). The results of the interaction effect of varieties and sowing dates were significant (P 0.05) for average individual plant height (cm), leaf area (cm 2 /plant -1 ), pod weight (g/pod -1 ), pod length, pod diameter (cm) and pod dry weight (g/plant -1 ) of green bean(table 2). The performance of green bean in-terms of dry weight of shoot and root and dry weight of pod were significantly (P 0.05) influenced by the interaction effects of spacing and sowing date, and varieties and sowing date, respectively (Table 1).

3 176 Sky. J. Agric. Res. Table 1. Analysis of variance for the studied traits. Traits Variety Spacing Variety x Spacing Variety Xx Spacing x Variety x Spacing x TMPY 1.12 ns 8.16 * ** 4.96 ns 4.64 ns ns ns TUMPY 6.62* 18.62* ** 4.02 ns 2.30 ns ns ns TNPPP 6.12* 45.46** ** 2.86 ns 9.09* 24.38* 14.78ns DWP 18.38** 14.36* ** 4.25 ns 8.18 * 35.10** ns DWSR 9.63** 6.68 ns ** 6.66 ns 7.33 ns 24.87* ns PL 0.55 ns 1.96 ns ** 3.07 ns 42.64** 7.90 ns 5.95 ns AIPW ** 0.63 ns ** 4.10 ns 32.30** ns 7.60 ns NSPP 2.83 (1.52 ns ) 1.74 (1.74 ns ) (20.35**) 9.89 (5.65 ns ) 4.98 (1.17 ns ) (11.16 ns ) 7.33 (9.10 ns ) PD 6.13* 6.65 ns ** 3.33 ns 21.77** 9.02 ns 8.77 ns PH 0.97 ns 3.40 ns 86.87** 2.66 ns 10.36* 5.33 ns 5.45 ns LA 2.50 ns 9.98* 79.98** 1.30 ns 41.23** ns ns NB: Values in bracket are based on square root transformation TMPY= Total Marketable Pod Yield, TUMPY= Total Unmarketable Pod Yield, TNPPP= Total Number of Pod per Plant, DWP= Dry Weight of Pod, DWSR= Dry Weight of Shoot and Root, PL= Pod Length, AIPW= Average Individual Pod Weight, NSPP= Number of Seed per Pod, PD= Pod diameter, PH= Plant height, LA= Leaf area. Table 2.Total percentage of marketable and unmarketable pod yield of green bean at different sowing date. Marketable pod yield (%) Unmarketable pod yield (%) July 3 rd b b July 18 th bc ab August 2 nd a c August 17 th c a Mean CV (%) LSD (p=0.05) Total marketable pod yield There was significant (P 0.05) effect of sowing date on the total marketable pod yield (kg/ha -1 ) (Table 1). Among the different sowing dates, green bean sowed on the 3 rd of July resulted in the highest total marketable pod yield (kg/ha -1 ); whilst the lowest total marketable pod yield (kg/ha -1 ) was obtained from green bean sowed on the 17 th of August. The highest total marketable pod yield was found for early sowing which might be due to the exposure of the green bean for long period of rainfall that resulted in higher vegetative growth that enhanced photo assimilate production in the pod. This result is in agreement with the findings of Yoldas and Esiyok (2007) who reported the lowest yield in late sowing due to a short vegetation period of the crop. The decline in total marketable yield of vegetable soybean with delayed sowing was attributed to the following reasons: i) a shorter season length leading to overall reduction in growth; ii) short days associated with low radiation and low temperature contributing to slower growth rates and lower pod set, and iii) a dramatic reduction on the relative duration of key phenol-stages, which mostly resulted from reduced photoperiod. The effect of spacing on total marketable pod yield (kg/ha -1 ) of green bean was significant at (P 0.05) (Table 1). The inter and intra row spacing of 40 cm 7 cm, gave the highest total marketable pod yield. Conversely, the lowest total marketable pod yield was obtained from green bean spaced at 50 cm 7 cm. This value is statistically similar with that of marketable pod yield that was obtained from green bean spaced with 40 cm 15 cm, and 40 cm 10 cm. Total unmarketable pod yield The effect spacing on total unmarketable pod yield (kg ha -1 ) was significant at (P<0.05) (Table 1). The spacing 40 cm 7 cm resulted in the highest total unmarketable pod yield of green bean. Conversely, the lowest total unmarketable pod yield was obtained from a green bean spaced at 40 cm 15 cm, and this value was statistically similar with the green bean sowed at 30 cm 15 cm spacing. The probable reason for the higher

4 Getachew et al. 177 Table 3. Total percentage of marketable and unmarketable pod yield of green bean at different spacing interval. Spacing Marketable pod yield (%) Unmarketable pod yield (%) 50 cm 7 cm c a 40 cm 15 cm ab b 40 cm 10 cm bc a 40 cm 7 cm a b 30 cm 15 cm a b Mean CV (%) LSD (p=0.05) unmarketable pod yield in the narrow spacing could be due to higher plant population at narrow spacing resulting in poor quality pods, that might have arose from intraplant competition and higher disease pressure. showed significant (P 0.05) effect on total unmarketable pod yield (kg ha -1 ) (Table 1). Sowing of green bean on the 3 rd of July and 18 th of July resulted in the highest total unmarketable pod yield (kg ha -1 ). The possible reason might be that early sowing resulted in higher total pod yield, which might have proportionally increased the unmarketable pod yield. In addition, early sowing exposes the pods to high rainfall and longer growing period, which increases the exposure of the pods to diseases and pests, and several other physical damages that compromises the marketability of the pods. revealed highly significant difference (P < 0.01) for both total marketable and unmarke pod yield of green bean.(table 2). Sowing of green bean on 3 rd of July produced 4326 kg ha -1 total pod yield, and the proportion of marketable pod yield was 60.8%. Sowing of green bean on the 18 th of July gave 3965 kg ha -1 of total pod yield; of which 57.0% was marketable; while sowing of green bean on the 2 nd of August resulted in 1950 kg ha -1 of total pod yield and marketable pod yield accounted 76.7%.Sowing of green bean with 40 cm 7 cm spacing resulted in the production of 5777 kg ha -1 of total pod yield; of which 65% was marketable. Sowing of green bean with 50 cm 7 cm spacing produced total pod yield of 4456 kg ha -1 ; of which 56% was marketable. Sowing green bean at the spacing of 40 cm 15 cm resulted in a total pod yield of 4362 kg/ha -1 and marketable pod yield accounted for 62.07% of the total pod yield. Sowing of green bean at the spacing of 30 cm 15 cm resulted in a total pod yield of 4817 kg ha -1 ; and out of this 63.52% was marketable. Sowing of green bean with 40 cm 10 cm spacing resulted in a total pod yield of 3866 kg/ha -1 ; out of this 58.38% was marketable (Table 3). Plant height In this study, variety interacted significantly with sowing date for plant height (Table 1). The maximum height was recorded from variety Melka-5 sown on 17 th August followed by variety Melka-1 sown on same date. In contrast, the lowest plant height was recorded from Melka-1 sown on 2 nd August. The possible reason for the observed increase in plant height of Melka-5 sown on 17 th August could be due to the extended prevalence of sunlight during the growth period which might have stimulated more growth on Melka-5 as compared to other sowing dates. This result also agrees with the work of Vieira et al. (1990) who reported that the depression of plant height could result from reduction of photosynthetic efficiency of a plant. It was also observed that Melka-5 sowed on the appropriate sowing date resulted in superior plant height as compared to Melka-1, implying that genotypically Melka-5 is superior than Melka-1. Leaf area and the interaction effect between variety and sowing date for total leaf area are highly significant (P 0.01). Likewise, there was significant (P 0.05) effect of spacing on the total leaf area of green bean (Table 1). The maximum leaf area was observed from Melka-5 sowed on 2 nd August followed by Melka-1 sowed on July 3 rd ; whereas the lowest leaf area was observed from Melka-1 sowed on 17 th August and Melka-5 sowed on 18 th July, respectively. Similar result was observed with the work of Singer et al. (1996) who reported that higher leaf area was recorded for late sowing than early sowing of green bean. Based on spacing, the highest leaf area was observed from plants spaced at 40 cm 7 cm. In contrast, the lowest leaf area was scored on plants spaced at 40 cm 15 cm which, however, was statistically apart with the values registered from plants spaced at 40 cm 10 cm and 30 cm 15 cm. Zhou et al. (2011) reported that competition between plants varied from spacing to spacing; wherein soybean plants planted in narrow rows spacing attained high light capture than in wider rows spacing.

5 178 Sky. J. Agric. Res. Table 4. Interaction effect of varieties and sowing date on pod length and average individual pod weight of green bean. Pod Length (cm) Variety Average Individual Pod Weight (g/pod) Melka-1 July 3 rd e e Melka-1 July 18 th a c Melka-1 August 2 nd c d Melka-1 August 17 th d g Melka-5 July 3 rd f f Melka-5 July 18 th b b Melka-5 August 2 nd a a Melka-5 August 17 th c d Mean CV (%) LSD (p=0.05) Table 5. Interaction effect of variety and sowing date on pod diameter of green bean. Variety July 3 rd July 18 August 2 August 17 Mean CV (%) LSD (P=0.05) Melka g a c e Melka f a b d Mean Pod length and pod diameter Pod length was significantly (P 0.05) influenced by the interaction effect of variety and sowing date (Table 1). The longest pod was obtained from Melka-1 sowed on 18 th of July, which was statistically similar with Melka-5 sowed on 2 nd of August; whereas the smallest pod length was obtained from Melka-5 sowed on July 3 rd (Table 4). This result could be due to the fact that in early sowing plants gets more rainfall for longer growing period that favored higher yield, which might have compromised pod length. The duration of plants exposed to lower temperature in early sowing is higher than late sowing, which might have resulted in reduced pod length. This result is also supported by the works of Corokalo et al. (1992) who reported that growth of fruits (pods) greatly depends on temperature, since high temperature accelerate fruit (pod) growth of green bean. Significant (P < 0.05) interaction effects was found between varieties and sowing date on pod diameter (cm) of green bean (Table 1). Thus, the widest pod diameter was obtained from Melka-1 and Melka-5 sowed on 18 th of July (Table 5). The narrowest pod diameter was obtained from Melka-5 sowed on July 3 rd. This result was also inagreement with the work of Marlene et al. (2008) who reported greater mean pod width (diameter) in late planting (17 mm) than early planting (15 16 mm). Number of seed per pod and average individual pod weight Number of seeds per pod was significantly (P 0.05) affected by sowing date (Table 1). The highest number of seeds per pod was obtained from green bean sowed on 18 th of July and 2 nd of August; whereas, the lowest number of seeds per pod was obtained from green bean sowed on the 17 th of August. This result agrees with the work of Qiu Ying Zhang et al. (2010) who reported higher total number of nodes per plant, total number of seeds per pod and number of pod sets per plant of green soybean in early sowing than late sowing. Thus, early sowing produced more branches and more pods and ultimately more seeds than late sowing. Shoot and root and pod dry weight There was a significant interaction effect between spacing and sowing date in the dry weight of pods of green bean. The highest dry weight of pods was found for spacing of 40cm 15cm sowed on 3 rd of July and 18 th of July, spacing of 30 cm 15 cm sowed on 3 rd of July and spacing of 50 cm 7 cm sowed on 18 th of July. This could probably be due to wider plant spacing that allowed plants get enough amount of moisture, with less competition between plants that resulted in better

6 Getachew et al. 179 Table 6. Interaction effect of varieties and sowing date on pod dry weight. Sowing Date Variety July 3 July 18 August 2 August 17 Mean CV (%) LSD (P=0.05) Melka c b 9.22 d 8.49 d Melka b a c 8.67 d Mean Table 7. Interaction effect of varieties and sowing date on total number of pod per plant of green bean. Sowing Date Variety July 3 rd July18 th August 2 nd August17 th Mean CV (%) LSD (P=0.05) Melka c c e f Melka a b d g Mean development of pods. The difference among sowing date could be probably due to longer period of moisture and nutrients availability at early sowing that resulted in more pod development and better yield relative to late sowing. The interaction effects between sowing date and varieties was significant (P<0.05) for pod dry weight in green bean (gplant -1 ) (Table 6). Variety Melka-5 sowed on the 18 th of July showed the highest dry weight of pod; while both Melka-1 and Melka-5 varieties sowed on August 17 produced the lowest pod dry weight. Total number of pod per plant Significant (P 0.05) interaction effects were found between varieties with sowing date, and spacing with sowing date. Accordingly, the highest total number of pod per plant was obtained from Melka-5 sowed on the 3 rd of July; whereas the lowest total number of pod per plant was obtained from Melka-5 sowed on the 171 th of August (Table 7). This is due to more number of plants that help the development of more vegetative parts in earlier sowing, which resulted in the production of more number of pods per plant, and the difference between the varieties could probably be genetic, in which Melka-5 might be more tolerant to low temperature relative to Melka-1. The largest total number of pods per plant was obtained from green bean sowed at the spacing of 40 cm 15 cm sowed on 3 rd of July and spacing of 30 cm 15 cm sowed on the 3 rd of July and on 18 th of July, respectively. The plant spacing showed similar effect as row spacing in affecting number of pods per plant, i.e., as the spacing increased, the number of pods per plant also increased. This increase in pods per plant in wider row and plant spacing is because of increase in nodes and branches that provided more fruit bearing space on the plant. Summary and conclusion Selection of best variety, with appropriate sowing date and using the optimum plant spacing are very important factors to increase the productivity and marketability of green bean. The present study indicated that green bean sowed on the 3 rd of July resulted in the highest total marketable pod yield; more number of seed per pods was observed from green bean sowed at on the 18 th of July and 2 nd of August. Similarly, the highest total marketable pod yield was obtained with plants spaced at 40 cm 7 cm. Among the varieties, Melka-5 gave the highest total unmarketable pod yield while Melka-1 variety gave the highest total marketable pod yield of green bean. Therefore, the results of this study has shown that different sowing date, spacing, and varieties had a significant positive influence on the yield of green bean. Hence, sowing of green bean at 3 rd July gives more marketable pod yield as compared to the other sowing date. From this study, it can be concluded that sowing of green bean at 3 rd July, spacing at 40 cm 7 cm and variety Melka-1 had a potential to increase the yield of green bean under Jimma condition. Hence, farmers and any new commercial growers and/or investors at Jimma and similar agro-ecology areas can use these packages for growing green bean with better quality and yield. REFERENCES Amanullah JI, HayatTF, KhanAI, Khan N(2002). Effect of sowing dates on yield and yield components of mash bean varieties. Asian J. Plant Sci., 1:

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