The aim of this study is to determine the functionality period of pistillate and staminate flower types and the pollen viability and normally developed pollen rates with pollen production in staminate flowers of monoecious pecan nut cultivars in Adana ecological conditions. In the study, 11 pecan nut cultivars named as Coctaw, Comanche, Harris Super, Hastings, Ideal, Mahan, Royal, Shawnee, Texhan, Western and Wichita were used. Flowering periods of evaluated cultivars were determined as homogamous, protandrous, partially protandrous and partially protogynous. The flowering dates occur between 3rd-20th May in 2016 and 30th April-18th May in 2017. The pollen viability rates were found to be quite high in all cultivars, but in 2017 the rates were lower than 2016. The lowest pollen viability rates were obtained from Hastings in 2016 and 2017 (60.0% and 61.6%) respectively and the highest rates were in Shawnee (89.1%) at 2016 and in Mahan (87.7%) at 2017. Normally developed pollen rates were adequate for all cultivars and the rates were differed between 92.30% and 98.42% in 2016, and 90.20% 97.24% in 2017. The differences between cultivars in terms of pollen production were significantly important. The pollen number in one catkin was found between 3.512.382 and 11.097.407 at 2016 and 6.101.233 and 14.958.453 at 2017.

The aim of this study is to determine the functionality period of pistillate and staminate flower types and the pollen viability and normally developed pollen rates with pollen production in staminate flowers of monoecious pecan nut cultivars in Adana ecological conditions. In the study, 11 pecan nut cultivars named as Coctaw, Comanche, Harris Super, Hastings, Ideal, Mahan, Royal, Shawnee, Texhan, Western and Wichita were used. Flowering periods of evaluated cultivars were determined as homogamous, protandrous, partially protandrous and partially protogynous. The flowering dates occur between 3rd-20th May in 2016 and 30th April-18th May in 2017. The pollen viability rates were found to be quite high in all cultivars, but in 2017 the rates were lower than 2016. The lowest pollen viability rates were obtained from Hastings in 2016 and 2017 (60.0% and 61.6%) respectively and the highest rates were in Shawnee (89.1%) at 2016 and in Mahan (87.7%) at 2017. Normally developed pollen rates were adequate for all cultivars and the rates were differed between 92.30% and 98.42% in 2016, and 90.20% 97.24% in 2017. The differences between cultivars in terms of pollen production were significantly important. The pollen number in one catkin was found between 3.512.382 and 11.097.407 at 2016 and 6.101.233 and 14.958.453 at 2017.

Plants have developed a number of monitoring systems to sense changes occurring in the environment and to coordinate their growth and development accordingly. Some plant groups have cold exposure requirement for a certain period to induce flowering. That process known as vernalization is case in point for mentioned systems. In many plants group, vernalization results in repression of floral repressor genes inhibiting floral transition. In this review, last epigenetic developments about vernalization mediated floral transition in Arabidopsis regarded as model organism for plants and other flowering plants will be discussed. Furthermore, similarity and differences in regulatory cycles in Arabidopsis and other flowering plants, changes in histone modifications at floral repressor loci and other epigenetic systems effective in vernalization will be discussed. To sum up, profound investigation of epigenetic mechanism behind the vernalization process plays an important role to decrease flowering-dependent yield losses.

Fotoperiyodizm, mevsimlik çiçeklerde çiçeklenme zamanını kontrol etmek için kullanılabilecek bir özelliktir. Kadife, mutlak veya fakültatif kısa gün ve nötr gün çeşitleri içeren bir yazlık mevsimlik çiçek türüdür. Aşırı sıcak ve uzun günlerin yaşandığı yaz aylarında nötr gün çeşitlerinde bile çiçeklenmede gecikmeler yaşanmaktadır. Bu çalışmada iki farklı nötr gün kadife çeşidinde (Discovery Orange ve Discovery Yellow) fotoperyodik koşulların (kısa gün ve uzun gün) çiçeklenme ve bitki gelişimi özellikleri üzerine etkileri araştırılmıştır. Uzun gün koşulu (14 saat) olarak doğal gün uzunluğundan yararlanılmıştır. Kısa gün koşulu (8 saat) ise karartma yapılarak yapay olarak oluşturulmuştur. Bitkilerde ilk çiçek tomurcuğu oluşma süresi, ilk çiçek açma süresi, bitki taç yüksekliği, bitki taç genişliği, yan dal sayısı, çiçek sayısı, ana çiçek sapı uzunluğu, çiçek sapı kalınlığı, kök boğazı kalınlığı, gövde kalınlığı ve bitkisel kuru ağırlıklar (kök, yeşil aksam ve tüm bitki) incelenmiştir. Araştırma sonucunda kısa gün koşulunun, ilk tomurcuk oluşma ve ilk çiçek açma sürelerini azalttığı belirlenmiştir. Yapay olarak yaratılan kısa gün koşulu, uzun gün koşuluna göre çiçeklenme süresinde ‘Discovery Orange’ çeşidinde 13 gün, ‘Discovery Yellow’ çeşidinde ise 5 günlük bir erkencilik sağlamıştır.