Research Article

Response of Male Pollinizers in Fruit Set, Yield and Quality of Date Palm (Phoenix dactylifera L.). Cv. Dhakki

Muhammad Aslam Shahid1, Muhammad Iqbal2* and Muhammad Niamatullah3

1Agriculture Extension Department, Dera Ismail Khan. Khyber Pakhtunkhwa, Pakistan; 2Department of Horticulture, Faculty of Agriculture, Gomal University, Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan; 3Department of Agriculture Economics, Faculty of Agriculture, Gomal University, Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan.

Received | March 10, 2016; Accepted | February 04, 2017; Published | March 07, 2017

*Correspondence | Muhammad Iqbal, Department of Horticulture, Faculty of Agriculture, Gomal University, Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan; Email: [email protected]

Citation | Shahid, M.A., M. Iqbal and M. Niamatullah. 2017. Response of male pollinizers in fruit set, yield and quality of date palm (Phoenix dactylifera L.). Cv. Dhakki. Sarhad Journal of Agriculture, 33(1): 108-116.

DOI | http://dx.doi.org/10.17582/journal.sja/2017.33.1.108.116

Keywords | Fruit set, Yield, Dhakki, Spath, Metaxenia

Introduction

Date Palm (Phoenix dactylifera L.) is an extensively cultivated tree of the World (Ragab, 1975). It occupies a pivotal position in the economic development of many countries including Pakistan. In addition, it also provides raw materials for many industries. Date is rich in sugar and a good source of energy (Baloch et al., 2006; Al-Abdulhai et al., 2011). The 100 gm of edible portion of date contains 1.42 calories comprises of 70% carbohydrates, 2.5% protein, 0.4% fats, 2.1% mineral, 15-30% moisture content and 3.9% fiber, Vitamin A, B-Complex and Vitamin E and K (Sarfraz et al., 2012). Pakistan is the 2nd major date exporting country after Tunisia. Major importers of Pakistani dates are Bangladesh, India, Itlay, Germany, Canada, Japan, UAE, Denmark, South Africa, Australia, Saudi Arabia, USA and UK (Amin et al., 2007). In Pakistan area under cultivation during 2012 and 2013 was 931 and 896 hectares with a total production of 557.3 and 524.6 tonnes (Anonymous, 2012-13). In Dera Ismail Khan many exotic and local date varieties are commercially grown. Amongst them local cultivar “Dhakki” is famous for its high yield and extra large size (Iqbal et al., 2009) which has grown throughout the Pakistan. Dhakki cultivar is producing low yield due to poor fruit setting by using pollen source of unknown potency. Artificial pollination is carried out due to its diocious nature. (Hussain et al., 1979). For successful pollination, high potent pollen sources play an important role (Iqbal et al., 2012; Dejrouni et al., 2015). In earlier studies various researchers, investigated the floral characterictics of male palms and their pollen effects on fruit set and yield. i.e. Al-Ghandi et al. (2002) and Iqbal et al. (2008; 2009) reported that males were differed in floral characterictics. Qureshi et al. (2009) and Ismail (2014) reported that germination percentage of pollen varies from one male to another. Awad and Al-Qureshi (2012) studied that pollens have direct effect on the receptivity of female flower. Bacha et al. (2002) and Abbas et al. (2012) determined that female flower receptivity was also different due to veritial aspect and genetic characterictics of female palm. The Pollens have direct effect on the meternal tissues of fruit which is known as metaxenia (Janick, 1979). The metaxenic effects on fruit were also reported by various researchers (Al-Ghamdi et al., 988; Shaheen et al., 1989; El-Makhtoun, 1990; Al-Khalifa 2006; Frag et al., 2012; Hafez et al., 2014). It is an established fact that some males are high potent as compared to others which contribute to increase in fruit set and yield (Iqbal et al., 2004). Ibrahim and Shahid (1994) tested the effect of six males on cv Hillawi and Khudrawi and reported that males significantly affected the fruit setting and yield. El- Salhey et al. (1997) studied the pollen viability of different males and their effect on fruit set and yield and concluded that males varied in respect of pollen viability, fruit set and yield. Rahemi (1998) documented the effect of different pollen sources on the fruit set and fruit characteristics. Abdul Hamid (2000), Halail and El-Kholey (2000), Osman and Soliman (2002), Marzouek et al. (2002), Al-Obeed and Abdul Rehman (2002) and El-Kosary and Soliman (2003) found that different male pollens have significant effect on fruit weight, size and pulp as well as fruit yield. Shafique et al. (2011) reported that pollens have direct effect on the physical and chemical properties of fruit. In addition, the role of pollen sources in improvement of quality, quantity and yield of date palm has been investigated by Damankeshan and Panahi (2013) and Omar et al. (2014).

Date growers of this area use pollen from males of unknown potency grown in wild grooves, consequently they get low yield. Realizing the importance of male, a study was designed to evaluate the floral characterictics, quantity and potency of their pollen grains in fruit setting, yield and quality. Earlier a little research work has been reported in this area on the effect of pollen sources on fruit set, yield and fruit physical characteristics and needs extensive work. Furthermore, no research work has been conducted on maturity time and chemical characteristics of Dhakki dates when fertilized by various pollen sources. The present study was, therefore, carried out with an attempt to improve the fruit set, yield and physico- chemical characteristics of date palm cv “Dhakki” through selecting best male source for fertilizing this promising cultivar.

Materials and Method

An experiment was conducted at Agriculture Extension Farm, Rakh Manghan Mandhra Kalan Dera Ismail Khan, Khyber Pakhtun Khwa, Pakistan during 2012 and 2013. Seven males were raised from seeds, symbolized as M1, M2, M3, M4, M5, M6 and M7 of irrespective age were selected from Dhakki area for recording of spath characteristics from the wild groves of date palm. The experiment was laid out in Randomized Complete Block Design having seven treatments and three replications. In this regard, twenty one Dhakki trees possessing 20 years of age with vigorous growth were selected for the present investigation. Row to row and plant to plant distance were maintained as 10 meters. These plants were propagated through conventional method by suckers. Male spathes were cut as protective sheath crack appeared at the top and then were brought to Laboratory. The protective sheath was removed for the separation of male strands. After separating the male strands, these strands were stored in refrigerator

Table 1: Spath characteristics and pollen viability % of male palms used in pollination during 2012 and 2013 seasons

Male spath characteristics were recorded using the method described by Iqbal et al. (2004).

Pollen viability (%): Before pollination, pollen viability percentage was determined as procedure adopted by Moreira and Gurgel (1941).

Fruit set (%): After four weeks of pollination, fruit set was calculated according to El Makhtun (1990).

Days to fruit set: The number of days to fruit set were recorded when two carpals of tricarpellary ovary were abscised in each spath and then mean days were calculated.

Fruit weight (g): Twenty fruits of each tree were weighed by electric balance and average weight of fruit was computed.

Fruit size (cm): The length and width of twenty (20) fruits from each tree was measured with the help of measuring scale and mean size of fruit was calculated.

Fruit drop (%): Percent fruit drop was calculated using following formula:

Days to maturity: The number of days to maturity were counted from fruit setting to when 50 % fruits colour was turned into yellow in each tree and then mean days were calculated.

Fruit yield (tree/kg): All the fruit bunches from each treatment were weighed and finally mean yield per tree (kg) was determined.

Moisture (%): Moisture content in fruit was determined by direct heating method as recommended by AOAC (1984).

Total soluble solids (Brix): Total soluble solids was determined by hand refractometer as per AOAC (1995).

Reducing sugars, non-reducing sugars and total sugars: Reducing, non reducing and total sugars were determined by Lane and Annon method as described as AOAC (1995).

Statistical Analysis: The collected data were analyzed statistically using Computer software MSTATC. The method of Analysis of Variance (ANOVA) was applied and means were separated using Least Significant Difference (LSD) test in accordance to procedure prescribed in Steel and Torrie (1980).

Results and Discussion

Male spath characters

Results indicated (Table 1) that maximum spath length was observed in M6 (103.21, 107.18 cm) during 2012 and 2013, respectively. The highest spath width was recorded in M5 (15.29, 16.58 cm). The maximum number of 18.52, 19.25 spath/tree were noted in M6. From the perusal of Table 1, the highest number of strand/spath and number of flower/ strand were observed in M3 (245.21, 240.53) and (84.29, 86.80), respectively. Maximum weight of pollen grain/ tree was recorded in M6 (150.07 and 147.57g). Maximum (12.13 and 11.18 g) weight of pollen grain/spath was found in M1 and pollen viability was noticed in M2 (93.78, 93.34 %). From the results, it was indicated that significant differences were observed among males regarding spath characteristics and pollen viability percentage. These results are in agreement with the findings of Marzouek et al. (2002); Iqbal et al. (2004; 2009), Hafiz et al. (2014) and Djerouni et al. (2015). It is evident from the results that male having maximum number of spath, number of strand/ spath and number of flower/ strand produced maximum pollen quantity and can be used to pollinate maximum number of female tree. Also males having high percentage of pollen viability caused maximum fruit setting. Hence, M2 is recommended for pollination of Dhakki date.

Fruit set (%): The data regarding fruit set percentage is given in Table 2. The results show that pollen sources had significant effect on the fruit set percentage in both years (2012 and 2013). The highest fruit set (90.17, 92.43%) was recorded when female trees were pollinated with M2. It was followed by M1 and M6 (79.67, 78.79%) and (69.40, 67.16%) respectively. The lowest fruit set (38.80, 40.41%) were recorded with pollination of M7. Difference in fruit setting behavior of male may be due to genetic character. These results are in line with the findings of El- Salhey et al. (1997) who reported variation in fruit setting of males. Similar results were reported by Iqbal et al. (2004; 2011).

Days to fruit set: Data indicated that minimum days to fruit set (14.32, 15.67) were observed when pollinated with M5 in 2012 and 2013 respectively (Table 2). The maximum days to fruit set (18.80, 19.17) were noted when trees pollinated with M1, followed by M6 (18.29, 18.49) and M3 (17.83, 18.00), in both years 2012 and 2013 respectively. The variation in days to fruit set may be attributed to genetic characters of pollen sources. These results are in agreement with the findings of Iqbal et al. (2011) and Djerouni et al. (2015) who reported that pollen sources had a significant effect on days to fruit set in date palm.

Fruit length (cm): Various pollinizers significantly affected the fruit length (Table 2). The lengthiest fruits (4.28, 4.27cm) were produced when pollinated with M2, whereas M4 produced shortest fruit (4.13, 4.14 cm) 2012 and 2013, respectively in both years of study. These results are contrary to the findings of Muhtasib and Ghnaim (2006) who reported that pollen sources had no significant effect on fruit length, Iqbal et al. (2008) and Omar et al. (2014) also reported that pollen sources significantly affected fruit length.

Fruit width (cm): Data showed significant effect of pollinizers on fruit diameter in 2013. However, results were non-significant during 2012. Maximum fruit diameter (2.28, 2.30 cm) was produced when pollinated with M2. Minimum fruit diameter (2.21, 2.22cm) was recorded by pollinating the cultivar with pollens of M5. However, there were non significant differences among the pollinizers M1 and M3. The results of 2013 are partially agreed with the findings of Hamid (2000) and Marzouk et al. (2002) who reported that pollen sources have significant effect on fruit width.

Fruit weight (g): The data pertaining to fruit weight of Dhakki was significantly affected by different male pollinizers during both study years (Table 2). Maximum fruit weight (22.33, 22.79 g) was recorded when pollination was done with M2 in 2012 and 2013, respectively. It was followed by M6 and (21.87, 21.67g) and M1 (21.40, 21.35g), respectively in 2012 and 2013. The M7 produced the minimum fruit weight (17.14and 17.21g) during both years of study respectively. Maximum fruit weight in M2 was associated with maximum size and moisture content in fruits. These results are in line with the findings of Omer et al. (2014) who reported that pollen sources had significant effect on fruit weight. Similar results were also reported by Simozrag et al. (2016).

Fruit drop (%): Data recorded for fruit drop percentage revealed that minimum fruit drop (32.22, 30.45%)

Table 2: Effect of pollen sources on fruit set, days to fruit set, fruit size, weight, fruit drop, days to maturity and yield of Dhakki date during 2012 and 2013

was recorded when pollinated with M2, whereas maximum fruit drop (40.48, 40.14%) was recorded with M1 during 2012 and 2013 respectively (Table 2). The results show that different pollinizers play vital role in fruit drop. These results are in conformity with the findings of Iqbal et al. (2011) and Shafique et al. (2011) who reported that fruit drop can be reduced by pollinizers.

Days to maturity: Minimum days to maturity (148.14, 148.12) were recorded by M1 which caused early maturity by 13.34, 15.04 days during 2012 and 2013, respectively (Table 2). M5 took maximum days to maturity (161.48. 163.81) in both years 2012 and 2013, respectively. Variation in days to maturity may be due to genetic make up of pollen sources. These results are in conformity with the findings of Al-Khalifa (2006) and Iqbal et al. (2011) who reported that pollen sources had significant effect on fruit ripening time. Abdel Malik (2012) reported similar findings.

Yield (kg/tree): Different pollen sources had exhibited significant effect on fruit yield during 2012 and 2013 (Table 2). M2 produced the highest fruit yield of 109.48, 104.83 kg /tree during 2012 and 2013, respectively. The lowest fruit yield of 52.82 and 52.13 kg/tree was noted when pollinated with M7 in both years. Results indicated that M2 produced highest yield which is due to maximum fruit setting, fruit weight, size, less fruit drop and higher moisture percentage. These findings are in accordance with the findings of Iqbal et al. (2008), Abdel Malik (2012) and Omer et al. (2014) who reported that fruit yield was significantly affected by various pollens sources, however contradict to the findings of Muhtasib and Ghnaim (2006), Shafique et al. (2011) and Iqbal et al. (2011) who reported non significant effect of pollen sources on fruit yield.

Moisture content (%): The highest moisture content of (68.17, 68.20 %) was found with pollination of M2 and lowest moisture content (60.34, 60.42%) was observed with M5 during 2012 and 2013(Table 3). Results revealed that fruit weight is associated with moisture content which was highest in M2. These results are supported by the findings of Omer et al. (2014) who reported that pollen sources had significant effect on fruit moisture.

Total soluble solids (Brix): Data recorded for total soluble solids percentage showed that the maximum

Table 3: Effect of pollen sources on fruit chemical characteristics of Dhakki date during 2012 and 2013

TSS (35.81, 36.28%) were recorded with M6, followed by M1 (34.41, 34.41%) in 2012 and 2013, respecively (Table 3). Minimum TSS of 32.45, 32.46% were recorded when pollinated with M7 in both years, respectively. These results are in conformity with the findings of Shafique et al. (2011) who reported that different pollinizers have significant effect on fruit TSS.

Reducing sugars (%): Reducing sugar is a mixture of glucose and fructose and released from the hydrolysis of sucrose. It ranged from 12.16, 13.82%. Table 3 indicated that maximum reducing sugars of 13.82, 13.44% were recorded with M6 male pollinizer, while minimum of 12.16, 12.17% were recorded with M7 in 2012 and 2013, respectively. These results are in conformity with the findings of Ibrahim et al. (2014) who reported that different pollinizers have significant effect on reducing sugars.

Non reducing sugars (%): Maximum non reducing sugars (5.15, 5.11%) were recorded with M6 pollinizer while minimum (4.33, 4.29%) were achieved with M7 in 2012 and 2013, respectively (Table 3). These results are in conformity with the findings of Rahmdel et al. (2014) who reported that different pollinizers had not significantly affected non reducing sugars.

Total sugars (%): Sugars content is an important attribute for quality assessment. Sugars are most prevalent compounds in date. Data presented in (Table 3) indicated that male pollinizers had a significant effect on total sugars. Maximum total sugars (18.97, 18.55 %) were recorded with M6 pollinizer, followed by M1 and M3 with 17.92, 17.93 and 16.79, 17.45%, respectively. Minimum total sugars (16.48, 16.47%) were recorded with M7 in 2012 and 2013, respectively. These findings are in accordance with the findings of Omer and Abdel (2014) who reported that total sugars were significantly affected with male pollinizers.

Conclusion

From the results, it is concluded that males differ greatly in floral characteristics like spath length, spath width, number of spath/tree, number of strand/spath, weight of pollen grain/ tree, weight of pollen grain/spath and pollen viability percentage. It is further indicated that males were variable in pollination response to fruit setting, yield and physico-chemical characterictics of fruits. Pollens of M2 pollinizer were found most effective for improvement of more than 50% fruit set and yield as compared to M7. Fruit quality was enhanced with pollination of M6 and can be recommended for commercial production under the Agro-climatic conditions of Dera Ismail Khan.

Acknowledegement

Authors are thankful to Agriculture Extension Department, Dera Ismail Khan for providing orchard facilities for conducting this research.

Author’s Contribution

All the authors contributed equally.

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