Abiotic stress tolerance breeding programs present a spectrum of perspectives, yet definitive solutions remain elusive, with each approach carrying its own set of advantages and disadvantages. This study systematically evaluates extant methodologies, comparing plant performance across varied genotypes and selection traits under optimal and stress conditions. The objective is to elucidate prevailing ambiguities. Ten homozygous lines (F8 generation) were assessed using a randomized block design alongside five control varieties, with four replicates cultivated under well-watered and deficit water conditions. It is noteworthy that six of the ten homozygous lines were cultivated exclusively under well-watered conditions (F3 to F7), while four lines experienced deficit water conditions (F3 to F7). All five control varieties underwent cultivation under both conditions. These findings underscore the necessity for tailored breeding programs attuned to specific environmental exigencies, recognizing that individual traits manifest divergent responses to varying conditions. It is evident that certain traits exhibit marked disparities under well-watered conditions, while others evince heightened differentiation under water deficit conditions. Significantly, our analysis reveals a pronounced interaction between irrigation regimes and selection traits, which serves to underscore the nuanced interplay between genotype and environmental stress.

The aim of the study was to assess the genetic structure and quantitative heritability of cotton yield, yield components and fiber quality parameters under well-watered (100%) and deficit (50%) irrigation conditions using a complete full diallel cross method with six cotton genotypes. The F₁ and F₂ generations were obtained to study the effect of irrigation conditions on genotypic variation and maternal effects on the traits studied. Parental, F₁ and F₂ generations were growed under full and deficit irrigation conditions and selected agronomic and fiber quality traits were measured. The data were analysed using various methods, including Griffing Method I, Model I analysis of variance, full diallel table analysis of variance, Jinks-Hayman diallel hybrid analysis. The Jinks-Hayman analysis of variance showed that dominant effects were more important in the inheritance of all traits, as indicated by the negative value of the difference between the additive variance and the dominance variance (D-H₁). In addition, the average degree of dominance (H₁/D)^1/2 was greater than 1, indicating the predominance of dominant gene action in inheritance. The study concluded that starting selection in the F₅–F₆ generation is appropriate for drought resistant cotton breeding studies. It also emphasised the importance of conducting drought resistant cotton breeding under drought conditions due to the differences in gene movement between well-watered irrigation and drought stress conditions. The study highlighted the importance of population selection, environmental factors, data collection and analysis interpretation in breeding studies. It suggested that the Griffing diallel analysis method is suitable for hybrid breeding studies, while the Jinks-Hayman type analysis method is suitable for studying the genetic structures of populations.

Bu çalışma, F8 generasyonunda pamuk (Gossypium hirsutum L.) döl sıraları arasından verim ve lif kalitesi bakımından üstün ileri pamuk hatlarını belirlemek amacıyla 2018 yılında Aydın Adnan Menderes Üniversitesi Ziraat Fakültesi Tarla Bitkileri deneme alanında augmented deneme desenine uygun olarak; tek bitki döl sıraları ve beş adet kontrol çeşit (Gloria, Flash, DP332, Candia ve Claudia) ile dört tekerrürlü ve sıra uzunluğu 12 m olacak şekilde damla sulama yöntemi kullanılarak tam (%100) ve kısıntılı sulama (%50) koşullarında yürütülmüştür. Çalışma sonucunda elde edilen veriler değerlendirildiğinde; tam sulama koşullarında Carmen x Nazilli-503 (hat no: 1), DPL-90 x Tamcot-22 (hat no: 10), BA-308 x Carmen (hat no: 38), DPL-90 x Tamcot-22 (hat no: 66) ve ST-373 x DPL-90 (hat no: 72) ileri pamuk hatlarının verim ve lif kalite özellikleri yönünden öne çıktığı gözlemlenmiştir. Kısıntılı sulama koşullarında ise Nazilli-503 x Tamcot-22 (hat no: 6), ST-373 x Carmen (hat no: 23), BA-308 x Nazilli-503 (hat no: 47), BA-308 x Carmen (hat no: 72), ve Ş-2000 x Tamcot-22 (hat no: 90) ileri pamuk hatlarının su stresine dayanıklı veya tolerant olduğu saptanmıştır. Tam ve kısıntılı sulama koşullarına uygun, verim ve lif kalitesi yüksek yeni pamuk çeşitlerinin tescil edilmesi amacıyla seçilmiş ileri pamuk hatları çeşit verim denemelerine alınacaktır.

The aim of this study is to analyse the cultivation areas, production amounts and foreign trade data of cotton plant in the world and Turkey from an economic point of view. The data on Turkey's cotton cultivation area, cotton production and fiber cotton import and export data for the 20-year period 2003-2022 were obtained from the Food Agricultural Organization (FAO). The data set was transferred to MS Excel spreadsheets and the trend analysis technique was used in MS Excel programme to obtain the trends in cotton cultivation area, cotton production amount and near future forecast values for eight years between 2023-2030. In addition, for the foreign trade balance data obtained from fiber cotton import and export data for the period 2000-2022, the change trends of the 23-year period and the eight-year near future forecast values between 2023-2030 were calculated. Cotton cultivation area has a decreasing trend between 2023-2030. While the forecast value of cotton cultivation area for 2023 is 417 thousand hectares, this value is predicted to decrease to 373 thousand 722 hectares in 2030. The trend in the amount of cotton production has a decreasing trend after 2022 and it is predicted that there will be no break in the amount of production between 2023-2030. The estimated foreign trade deficit in fiber cotton for 2023 is 964,516 tonnes and for 2030 is 1,106,672 tonnes. The main reasons for the decrease in cotton cultivation areas are the increases in input prices such as fertilisers, pesticides and seeds. In order to eliminate the foreign trade deficit in cotton, studies should be carried out to enter new markets and increase the share in existing markets. In addition, it should be aimed to create a sustainable cotton sector by investing in R&D activities and entering new markets.