A series of experiments were conducted to determine different factors affecting the fruit set, pomological characteristics, fruit drop and fruit bunch weight in date palm (Phoenix dactylifera L.) cultivar Dhakki under the agro-climatic conditions of Dera Ismail Khan, Pakistan.
This dissertation is comprised of sixteen chapters. First three chapters deal with general Introduction, Literature Review and Methodology used in various experiments. Chapter four gives information about different characteristics of 15 males, collected from different wild grooves and were designated as M1-M15. Screening of males for vegetative, reproductive characters fruit set and fruit yield per bunch on pollination of Dhakki date was carried out during the year 2000. It was found that males varied in vegetative and reproductive characters. The significant fruit set of 88.33% occurred from M5 pollens while the minimum 23.31 % was recorded in M1 pollens. Fruit yield per bunch ranged from 3.26 kg to 7.00 kg. The maximum fruit yield was recorded in Ms while minimum bunch weight was achieved in M1.
Chapter five envisages the experiment regarding evaluation of whorl-wise floral characters of nine males during 2001 and 2002. The parameters studied days to spathe opening, flower persistent days, length and width of spathe, length of strand, spike length, number of strands per spathe, number of flowers per strand, number of flowers per spathe and weight of pollen grain per spathe. Males as well as whorls was different significant in all parameters mentioned above except number of flowers per spathe and weight of pollen grain per spath were non-significant. Maximum pollens weight was observed in M9 and M3 during 2001 and 2002 respectively. Amongst whorls, the highest pollen weight was recorded in W2 followed by W1 and W3.
The study regarding pollen viability is reported in Chapter 6. The pollens of nine males were stored in refrigerator (4°C) and room temperature packed in plastic bags and glass jars for 12 months and their viability determined after different intervals. Pollen viability differed significantly under both storage conditions during both years of study while packing materials were non-significant. The maximum pollen viability was found in M1 and M2 pollens under both storage conditions. The pollen viability was slightly better in glass jar as compared to plastic bags.
Male whorl pollen grain play an important role in fruit set. Studies conducted regarding pollination with pollens of different males and whorls are reported in Chapter 7. These studies suggest that the M1 and M2 were highly significant in fruit set during both the years. These males were superior in pomological characters; fruit set and fruit yield per bunch. The pollen grains of second whorl (W2) were more effective in fruit setting than others.
Females of different age (8, 10, 12, 14, 16,20 and 25 years) were pollinated with M1 pollens and results are incorporated in Chapter 8. Age of plant exhibited significant effects on fruit set during 2001 while it was not significant during 2002. The maximum fruit drop was recorded in 25 years age of plant whereas maximum fruit yield per bunch was observed in 12 years old tree.
Pollination technique is one of the important factors for obtaining high and sustained productivity. Chapter 9 deals with different pollination techniques. Placement techniques proved superior to dusting and liquid spray of pollens with respect to fruit set, pomological characters and fruit yield during both years.
Pollination time is an important factor for fruit set. Eleven pollination times viz. pollination before one day spathe opening, pollination on spathe opening day and pollination after one, two, four, six, eight, ten, twelve, sixteen and twenty days of spath opening were tested. The significantly highest fruit set, less fruit drop, pomological characters and maximum fruit bunch yield was recorded with pollinations. (Chapter 10) one day before spathe opening on spathe opening day, one, two and four days after spathe opening).
Male pollinizer plays an important role in fruit set which depends upon male and female incompatibility. In Chapter 11, the females of cv. Dhakki, Shakri and Zhaidi were fertilized with pollens of five males maximum significantly fruit set was recorded in M4 while highest fruit weight, length and pulp weight were found in M2 and M1. Amongst varieties (females), Shakri and Dhakki noted maximum fruit set in cv. Zahidi followed. However, maximum fruit drop was observed in cv. Dhakki followed by Shakri and Zahidi. Fruit size and fruit yield per bunch were highest in Dhakki.
Pollination at specific daytime also plays an important role in fruit setting. Studies regarding pollination on second day of spathe opening at different times of day (08:00, 09:00, 10:00, 11 :00, 12:00, 13:00, 14:00 and 15:00 hours) were conducted and results are reported in Chapter 12. Maximum fruit set was achieved when pollination was done at 11 :00 hours during both years.
Rainfall after pollination adversely affects fruit set and consequently the yield. Effect of water spray- to determine the influence of rainfall after pollination has been reported in Chapter 13. Minimum fruit set was observed in treatment with water spray just after pollination. The maximum fruit set was observed in sprays after 6, 7 and 8 hours of pollination. Maximum fruit bunch weight was recorded with water spray after six hours of pollination. The highest fruit yield per bunch was observed with water spray after 7 hours of pollination.
Chapter 14 deals with summary, chapter 15 envisages with conclusion, and chapter 16 comprises literature cited.