The determination of cotton (Gossypium hirsutum L.) genotypes for improvement of drought tolerant cotton varieties

Küresel iklim değişikliğinin sonucu ortaya çıkacak olumsuz yönlerinden etkilenecek ülkeler arasında Türkiye de yer almaktadır. Bu nedenle su stresine tolerant pamuk genotiplerinin geliştirilmesi gelecekte pamuk üretiminin devamlılığı açısından önemlidir. Bu çalışmada yurt dışından ve Nazilli Pamuk Araştırma İstasyonu Müdürlüğü' nün genetik stoklarından sağlanan 48 adet pamuk genotipi materyal olarak kullanılmıştır. Bu çalışma, pamuk genotiplerinin su stresine karşı tepkilerini belirlemek ve su stresine dayanıklı/tolerant pamuk genotiplerini belirlemek amacıyla yapılmıştır. Denemeler Adnan Menderes Üniversitesi Ziraat Fakültesi ve Özaltın Tarım İşletmeleri Sanayi ve Ticaret Anonim Şirketi-Koçarlı deneme alanlarında olmak üzere iki lokasyonda tam (% 100) ve kısıntılı (% 50) sulama koşullarında damla sulama sistemi kullanılarak Augmented deneme deseninde dört tekerrürlü olarak yürütülmüştür. Kısıntılı sulama uygulamasının tüm pamuk genotiplerinde ortalama kütlü pamuk verimi, 1. ve 2. pozisyon koza tutma oranı, bitkide koza sayısı, lif uzunluğu, lif yeknesaklığı ve lif dayanıklılık değerlerini düşürdüğü, çırçır randımanı ve lif incelik değerlerini artırdığı, koza kütlü ağırlığı, lif esnekliği ve 100 tohum ağırlık değerlerini ise etkilemediği gözlenmiştir. Çalışmada yer alan pamuk genotiplerinin kütlü pamuk verimi, sulama suyu kullanım etkinliği ve kuraklık hassasiyet indeks değerleri bakımından birlikte değerlendirildiğinde; CABU/CS2-1-83, Coker 208, TKY 9409, TKY 9304, Semu SS/G, Nazilli 84-S ve Taşkent 1 genotiplerinin kuraklığa hassas, Lachata, MS-30/1, NGF-63, NP EGE 2009, Eva, NIAB 111 ve NIAB 999 genotiplerinin ise kuraklığa tolerant oldukları dolayısıyla su stresine tolerant yeni pamuk çeşitlerinin geliştirilmesinde ebeveyn olarak kullanılabileceği sonucuna varılmıştır.Turkey is among the countries that will be negatively affected by global climate change in the future. Therefore it is important to improve drought tolerant cotton varieties in terms of continuousness of cotton production in the future. In this study 48 cotton genotypes which were obtained from foreign countries and Nazilli Cotton Research Station were used as research materials. The purpose of the study was to determine the response of cotton genotypes to water stress and to select water stress resistance/tolerant cotton genotypes. The study was conducted under two locations; Adnan Menderes University Agriculture Faculty and Özaltın Agriculture Company Experiment Fields. The cotton genotypes were grown under full (100 %) and deficit (50%) irrigation. The experiment design was Augmented design with four replications. Water deficit decreased mean seed cotton yield, 1. and 2. Position boll retention rate, boll number, fiber length, uniformity index, and fiber strength, increased mean lint percentage and fiber fineness, and did not affect boll weight, elongation and seed weight. The result of this study showed that based on seed cotton yield, the irrigation water use efficiency and drought susceptibility index, CABU/CS2-1-83, Coker 208, TKY 9409, TKY 9304, Semu SS/G, Nazilli 84-S and Taşkent 1 genotypes would be drought sensitive, Lachata, MS-30/1, NGF-63, NP EGE 2009, Eva, NIAB 111 ve NIAB 999 genotypes would be drought tolerant and would be used as a parent in the breeding program to improve drought tolerant cotton genotypes

Identification of stable QTLs for fiber quality and plant structure in Upland cotton (G. hirsutum L.) under drought stress

Cotton is an economically important commodity for nearly fifty industries including the textile sector which is largely based on cotton fiber. Identification of markers linked to loci for fiber traits under drought stress may be particularly beneficial because such loci could provide the genetic adaptability needed to produce good fiber under water limitation. In the present study, 177 simple sequence repeat (SSR) markers were used to detect significant quantitative trait loci (QTLs) linked to 11 fiber quality and plant structure traits in a panel of 99 Upland cotton (Gossypium hirsutum L.) genotypes using GLM and MLM analysis. The fiber quality traits, including fiber length (FL), fiber fineness (FF), fiber strength (FS), fiber elasticity (FE), fiber uniformity (FU), spinning conversion index (SCI), earliness (EAR), 1st position boll retention (1st PBR), 2nd position boll retention (2nd PBR), total boll number (TBN) and plant height (PH), were tested under both well-watered and water-limited irrigations in two locations. At both locations, GLM identified a total of 74 and 70 QTLs under well-watered and water limited conditions, respectively, at p ≤ 0.005. MLM detected seven and 23 QTLs under well-watered and water-limited conditions, respectively. Of the identified QTLs, some QTLs were detected in both locations: three for well-watered and two for water-stress conditions. Moreover, a total of 19 QTLs were stable under both watering-regimes. The QTLs identified herein could be useful in the development of cotton cultivars that have adaptability to drought conditions worldwide.TUBITA

Genome-wide association mapping of yield components and drought tolerance-related traits in cotton

Drought causes serious yield losses in cotton production throughout the world. Association mapping allows identification and localization of the genes controlling drought-related traits which will be helpful in cotton breeding. In the present study, genetic diversity analysis and association mapping of yield and drought traits were performed on a panel of 99 upland cotton genotypes using 177 SSR (simple sequence repeat) markers. Yield parameters and drought tolerance-related traits were evaluated for two seasons under two watering regimes: water-stressed and well-watered. The traits included seed cotton yield (SCY), lint yield (LY), lint percentage (LP), water-use efficiency (WUE), yield potential (YP), yield reduction (YR), yield index (YI), drought sensitivity index (DSI), stress tolerance index (STI), harmonic mean (HM), and geometric mean productivity (GMP). The genotypes with the least change in seed cotton yield under drought stress were Zeta 2, Delcerro, Nazilli 87, and DAK 66/3 which were also the most water-use efficient cultivars. The average genetic diversity of the panel was 0.38. The linkage disequilibrium decayed relatively rapidly at 20–30 cM (r 2 ≥ 0.5). We identified 30 different SSR markers associated with the traits. Fifteen and 23 SSR markers were linked to the traits under well-watered and water-stress conditions, respectively. To our knowledge, most of these quantitative yield and drought tolerance-associated loci were newly identified. The genetic diversity and association mapping results should facilitate the development of drought-tolerant cotton lines with high yield in molecular breeding programs.TUBITAK (3110087