اثر تیمار gaba و lab بر عملکرد و خواص بیوشیمیایی گوجه‌فرنگی تحت تنش کم آبیاری

یکی از علائم اصلی حساسیت به تنش‌های محیطی، کاهش عملکرد گیاه است. برای کاهش و تعدیل اثرات مضر تنش محیطی، ترکیبات جدید lactic acid bactria (lab) و gaba (γ-aminobutyric acid) کمتر مورد استفاده قرار گرفته‌اند در حالی که استفاده همزمان این دو بسیار مفید است. پژوهش حاضر به منظور کاهش اثرات تنش آبیاری آزمایشی به طور طرح فاکتوریل در قالب بلوک‌های کامل طراحی و اجرا شد. در این آزمایش برای اعمال تنش کم آبیاری، آبیاری در دو سطح رطوبت خاک (آبیاری کامل 90 درصد رطوبت ظرفیت مزرعه‌ای، 50 درصد رطوبت ظرفیت مزرعه‌ای خاک) به عنوان فاکتور اول و تیمارهای محلول‌پاشی gaba در غلظت 1 و 2 میلی‌گرم در لیتر همراه با lab  در دو غلظت 5 و 10 درصد و یک تیمار شاهد به عنوان فاکتور دوم در نظر گرفته شد. بذور گیاهان گوجه فرنکی رقم chef برای تولید نشا در سینی‌ها 12×12 کشت شد و در گلخانه نگه داری شد. پس از تولید نشاء گیاهان به مزرعه اصلی منتقل شد. 20 روز بعد از انتقال به زمین اصلی و استقرار گیاهان اعمال تنش‌های آبیاری همراه با محلول‌پاشی گیاهان با gaba و lab انجام شد. دو هفته بعد از آخرین محلول‌پاشی میوه‌ها برداشت و میزان وزن میوه و عملکرد یک بوته همراه با صفات هدایت روزنه‌ای، نشت یونی و محتوای نسبی آب مورد بررسی قرار گرفت. نتایج حاصل نشان داد که محلول‌پاشی gaba و lab بر عملکرد گیاهان گوجه‌فرنگی به‌ویژه در شرایط تنش خشکی تاثیر گذاشته و تا حدی اثرات منفی تنش خشکی را جبران کرده است. استفاده از gaba و lab میزان عملکرد را در گوجه‌فرنگی افزایش داد. بیشترین وزن میوه (2/44 کیلوگرم) در بوته طی شرایط آبیاری کامل و در زمان استفاده از gaba در غلظت 2 میلی‌گرم در لیتر به دست آمد. با توجه به نتایج پژوهش حاضر طی آبیاری در 50 درصد رطوبت ظرفیت مزرعه‌ای استفاده از gaba در غلظت 2 میلی‌گرم در لیتر lab با غلظت 10 درصدی تاثیر قابل قبولی را کاهش اثرات تنش آبیاری در گوجه‌فرنگی داشته است.

the effect of gaba and lab treatment on yield and biochemical properties of tomato under irrigation deficit stress

1. introduction: one of the main symptoms of sensitivity to environmental stress is the decrease in plant performance. tomato، with the scientific name (solanum lycopersicum l) from the solanaceae family، is one of the valuable plants from an economic and nutritional point of view. drought has been one of the main factors limiting agriculture in recent years، especially in iran، which is located in an arid and semi-arid region، and it has become more visible and effective in recent years. in 2017، the food and agriculture organization reported its global production as 182.3 million tons، and iran، with the production of 6.17 million tons and 3.4% of the world's production، occupies sixth place in the world's tomato production. studies have shown that this plant is a rich source of minerals and vitamins، and its distinct nutritional properties play an important role in reducing the risk of diseases because they contain high amounts of antioxidants such as carotenoids، polyphenols، ascorbic acid، and many others. to reduce and moderate the harmful effects of environmental stress، the new combinations of lab and gaba have been used less often، while the use of these two together is very beneficial. 2.      materials and methods:  to reduce the effects of experimental irrigation stress، the present research was conducted in the research farm of the department of horticulture، faculty of agriculture and natural resources، mohaghegh ardabili university، as a factorial experiment in the form of a completely randomized design. in this experiment، to apply low irrigation stress، irrigation at two levels of soil moisture (full irrigation 90% of field capacity moisture، 50% of field soil capacity moisture) as the first factor and gaba foliar spraying treatments in concentrations 1 and 2 mg/liter along with lab in two concentrations of 5 and 10% and a control treatment was considered as the second factor. to obtain the field capacity of the soil (the amount of moisture that remains in the soil after the release of gravity water) and the percentage of moisture in the field soil، a field of one square meter was irrigated until saturation and covered with plastic. after stopping irrigation and water drainage، soil moisture was measured at six-hour intervals at the root growth depth (20 cm) with a hygrometer. this process continued until the moisture content was approximately equal in several consecutive measurements. this percentage of humidity is considered equal to the humidity of the field's capacity، and irrigation treatments are considered based on a percentage of this amount of soil moisture. the seeds of chef tomato plants were planted in 12 x 12 trays to produce seedlings and kept in the greenhouse. after the production of seedlings، the plants were transferred to the main farm. 20 days after transferring to the mainland and establishing the plants، irrigation stress was applied along with spraying the plants with gaba and lab. two weeks after the last spraying، the fruits were harvested، and the fruit weight and yield of a plant، along with stomatal conductance، ion leakage، and relative water content، were investigated.3.      results and discussion: the results showed that foliar spraying of gaba and lab affected the performance of tomato plants، especially in drought stress conditions، and partially compensated for the negative effects of drought stress. application of gaba and lab increased the yield in tomato. the highest fruit weight (2.44 kg) per plant was obtained under full irrigation conditions and when gaba was used at a concentration of 2 mg/liter. our results showed that the plants treated with gaba at a concentration of 2 mg/liter had a higher efficiency than the plants treated with lab and the control. with the increase of irrigation stress، the rate of ion leakage increased، and the relative water content of leaves decreased. despite the positive effect of lab at a concentration of 10% in reducing ion leakage during irrigation stress، the use of gaba at a concentration of 2 mg، in addition to reducing the amount of ion leakage، increased the relative water content and stomatal conductance in tomato leaves in this experiment. in addition، the results showed us that with increasing drought stress، stomatal conductivity decreases. stomatal closure is the first response to drought stress in most plants، and stomatal closure prevents water loss from transpiration pathways. also، the concentration of 2 mg/l gaba in normal irrigation conditions has increased stomatal conductance، and in irrigation stress، in field capacity humidity of 50% has prevented the reduction of stomatal conductance to a large extent. according to the results of the present study، during irrigation at 50% humidity of the field capacity، the use of gaba at a concentration of 2 mg/liter and lab at a concentration of 10% had an acceptable effect on reducing the effects of irrigation stress on tomatoes.5.      conclusion:  in this study، foliar spraying of gaba and lab affected the performance of tomato plants، especially under drought stress conditions، and partially compensated for the negative effects of low irrigation stress. application of gaba and lab increased the yield in tomato. therefore، it seems that in order to achieve the goals of sustainable agriculture، it is recommended to use lab and gaba in different concentrations instead of chemical fertilizers to increase the efficiency and performance of plants during irrigation stress.