خاکپوش های معدنی، نظیر پومیس در خاک باعث افزایش نگهداری آب، کاهش تبخیر و مصرف بهینه آب گردیده و بنابراین خاکپوش از این طریق می تواند تاثیر بسزایی در بهبود عملکرد و رشد در شرایط تنش کمبود آب داشته باشد. این پژوهش به صورت فاکتـوریل بر پایه طرح بلوک های کامل تصـادفی با سه تـکرار به صورت مزرعه ای اجرا شد. در این تحقیق اثرات چهار سطح پومیس شامل بدن مصرف خاکپوش (شاهد)، 30، 60 و 90 تن در هکتار خاکپوش و سه سطح آبیاری شامل 50 (تنش شدید)، 70 (تنش ملایم) و 100 (بدون تنش) درصد تبخیر از تشتک تبخیر کلاس A، روی برخی صفات فیزیولوژیک ذرت (هیبرید اصلاح شده ماکسیما) مورد بررسی قرار گرفت. صفات فیزیولوژیک گیاه ذرت، به طور معنی داری تحت تاثیر پومیس و آبیاری قرار گرفت. بیشترین و کمترین میزان شاخص کلروفیل، محتوای نسبی آب برگ، هدایت روزنه ای و وزن تر و خشک زیست توده به ترتیب از تیمار پومیس 90 تن در هکتار و شاهد مشاهده شد. همچنین، بیشترین و کمترین دمای سطح برگ از تیمار شاهد و پومیس 90 تن در هکتار به دست آمد. شاخص کلروفیل در تیمار 90 تن پومیس در هکتار نسبت به تیمار شاهد و تیمار 30 تن پومیس در هکتار به ترتیب افزایش 52 و 26 درصدی و هدایت روزنه ای در تیمار آبیاری ۵۰ درصد نسبت به تیمارهای آبیاری 10۰ و 7۰ درصد تبخیر از تشتک تبخیر به ترتیب کاهش 42 و 23 درصدی را نشان داد. بنابراین، استفاده از 60 تن پومیس در هکتار و آبیاری بر اساس 70 درصد تبخیر از تشتک تبخیر می تواند مؤثر بوده و تاثیر معنی داری بر ویژگی های رویشی گیاه و عملکرد خواهد داشت. تفاصيل المقالة

Physiological traits of tomato including its resistance to stresses are a main breeding goal in producing new cultivars. This study reports on a combining ability analysis investigating the variance of general and specified combing abilities for some important physiological characteristics as a whole as well as their effects for individual parents and hybrids of 19 tomato genotypes of tomato under drought stress. Three commercial innate lines and four analyzers were used in a line-to-tester crossing plan at Ilam University, Iran. There was a significant difference between genotypes (parents and crosses) in all characteristics at three levels of stress. Evaluating the impacts of common combining capacity analyzers and lines showed that neither a single line nor an analyzer was a commendable common combiner for all of the characteristics examined at all three push levels. Estimation of the effects of specific combining ability indicated that for each specific physiological trait, a specific hybrid showed the highest effect at all three stress levels. In all of the traits under study, specific combining ability variance had a higher estimation than general combining ability variance, and the genetic variance ratio of additive variance to non-additive variance was smaller than one, indicating that non-additive gene action predominated in the inheritance of all of the characteristics in the three levels of stress. The degree of dominance under three levels of stress was higher than one for all attributes except total soluble solids, and it seems that dominance in the genetic locations controlling these traits is superseded. تفاصيل المقالة

One of the most important factors in controlling the quality of fresh flowers is stem length because it is a major determinant of cut stem productivity. The grading and marketing of most cut flowers, like roses, are generally based on stem length. The present study aimed to evaluate the effects of cut rose flower stem length on vase life and water balance of rose cv. ‘Bingo White’ in a factorial experiment based on a Completely Randomized Design (CRD). Cut stem length was used at four levels of 25, 35, 45, and 55 cm kept in 50 mg/L sucrose sodium hypochlorite solution at two levels of 0 and 2% as preservative solutions with three replications at 23 ± 2°C with 65 ± 5% relative humidity and 12μmol/m2 s of light intensity (supplied by cool white fluorescent lamps) for 12 hours up to the end of vase life. Some qualitative and quantitative characteristics including vase life, flower and leaf water potential, ion leakage, membrane stability index (MSI), and leaf stomatal conductance were recorded. The results showed that the longest vase life (17 days) was significantly (P < 0.01) observed at the lowest stem length (25 cm) and the shortest vase life (10 days) was related to the highest stem length (55 cm). The lowest rate of leaf and petal ion leakage was significantly (P < 0.05) observed in the lowest stem length (25 cm). The stem lengths of 35 and 45 cm, however, did not significantly differ from the stem length of 25 cm. The lowest rate of leaf and petal membrane stability index was significantly (P < 0.05) related to 55 cm stem length. The highest rate of flower and leaf water potential was significantly (P < 0.01) obtained from 35 cm stem length as compared with other treatments. Stomatal conductance decreased over time, but it was not affected by stem length treatments significantly. Generally, our results showed that the shorter cut stem length treatment (25 cm) with the sucrose solution (2%) not only had the greatest effect on extending vase life but it also improved the water status, decreased the ion leakage, and increased the flower membrane stability index. تفاصيل المقالة