EVALUATION OF SOME IMPORTED PECAN VARIETIES UNDER GIZA GOVERNORATE ENVIRONMENTAL CONDITIONS

Abstract

This study was carried out during two successive seasons of 2007 & 2008 to examine the performance of six new pecan varieties imported from Georgia, U.S.A. namely: Burkett, Desirable, Pawnee, Success, Western Schley, and Wichita. The experimental trees were grown at the Horticulture Research Institute, Giza, Egypt. This evaluation includedmorphological, flowering, yield and fruit quality, physical characteristics as well as kernel oil fatty acids composition and the ability to vegetative propagation by grafting. The Effect of environmental conditions on dichogamy phenomenon was also studied.It can be clearly noticed that, there is a positive relation between shoot length & diameter, av. No. of leaves per shoot and internodes length, where Burkett variety was the superior in this concern, while, Pawnee variety exceeded the others in twig length and No. of shoots/twig. Desirable var. recorded the highest No. / of leaflets/leave and leaflet area. Western Schley had smaller tree size. There was an obvious varietals difference in pecan bud developmental stages (dormant, vegetative and starting buds for staminate or pistillate inflorescences). The highest No. of the abovementioned buds as well as total No. of such buds and No. of fruits/shoot was observed in Western Schley variety except for No. of vegetative buds. Fruit set (%) averaged between 66.04 & 66.04 in Wichita to reach 85.60 & 82.57 in Desirable. Number of days in which pollen shed coincides with stigma receptivity varied between the studied varieties, where there was more consistent period of overlap in Pawnee, Success & Western Schley varieties. The previously mentioned varieties can be classified as protandrous (type, 1), whereas, Burkett, Desirable & Wichita varieties as protogynous (2). Moreover, Wichita can be considered a good pollinator for most other studied varieties. Pollen shedding period in Wichita extended with the increase of relative humidity and lower temperature. Burkett followed by Success varieties started and ended to crack shuck and harvesting earlier than other varieties. Western Schley, Desirable & Burkett varieties had an excellent kernel ercentage, respectively, whereas, Pawnee variety was the poorest. Varieties with high nut weight had lower No. of nuts /kg. Desirable followed by Burkett produced the highest yield, while, Success was the lowest. In regard to kernel oil content (%), Desirable followed by Western Schley kernels were the richest. The main compositional characteristic of pecan kernel was the high concentration of oleic acid and very low content of Linolinec acid. It is also interesting to note that, successful grafts (%) varied between varieties from 33.33 % in Western Schley to reach 93.33 & 91.66 % in Desirable & Success, respectively. As a conclusionunder the same conditions of the present study Burkett & Success may be recommended as early cropping varieties; Wichita as a good pollinator; Western Schley as a small size tree which can be helpful in increasing number of trees / Fed. which in turn increases yield/Fed. as well as may facilitate the trees cultural practices. The primary pecan varieties Desirable & Burkett performed superior to other varieties in terms of yield; Western Schley and Desirable as varieties that have higher percentages of kernel and oil content and Desirable & Success are characterized by their easy to vegetative propagation. Moreover, all of these varieties were likely to complete their developmental growth cycle, which indicates low chilling requirements character and can be grown commercially in Egypt.