A recalcitrant rooting variety cannot increase POX activity sufficiently before rooting. Therefore applications that could increase POX activity in stem cuttings during rooting may facilitate increased rooting in such rootstocks.

(1) Background: Silicon (Si) and nitric oxide (NO) have been proven to protect against cellular injury caused by stress conditions, mostly by salinity and water stress in agriculture. (2) Methods: The goal was to study the effect of soil applications of NO, Si, and their combination (Si+NO) on the response of Myrobalan 29C rootstocks (Prunus cerasifera Ehrh.) subjected to water stress and well-watered conditions. (3) Results: The results showed that water stress decreased growth parameters (i.e., leaf area, shoot dry weight, root fresh weight, shoot fresh weight, root dry weight, and relative shoot diameter), physio-biochemical parameters (i.e., chlorophyll and relative water content in leaves), and leaf and root minerals (i.e., P, Ca, Fe, and Zn in leaves and N, K, Ca, and Zn in roots), compared to well-watered plants. Under these conditions, all treatments mitigated the detrimental effects of water stress on Myrobalan 29C rootstocks, being the most effective the Si+NO treatment. (4) Conclusions: These findings briefly highlight that the combination of silicon and nitric oxide may provide greater tolerance to water stress in Myrobalan 29C rootstocks.

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The aim of this study was to confirm the hypothesis that pretest temperature changes could alter the cold hardiness of the grapevine dormant buds and eventually the result of differential thermal analysis (DTA) test. For this reason, dormant buds of 'Karaerik' grape cultivar were collected at different times and tested using different DTA procedures. Dormant buds taken at nine different sampling temperatures (8, 6, 5, 3, −1, −3, −4, −5, and −9°C) were exposed to freezing test according to three DTA test approaches (TestA-A, TestA-4 and Test20-4, to represent ambient storage and ambient test, ambient storage and 4°C test, and 20 ± 2°C storage and 4°C test or standard DTA method, respectively) to verify our hypothesis in 2015-16 and 2016-17. The LTE (low temperature exotherm) temperatures were determined as the indicator of death of primary buds at grapevines' dormant buds, tested according to TestA-A approach, TestA-4 approach and Test20-4 approach (the standard methodology). It was found that temperature changes such as rapid cooling, warming and thawing in the TestA-4 approach, and warming-cooling and melting-cooling in the Test20-4 approach altered LTE values of dormant buds depending on the test start temperature. It was determined that the LTE values of dormant buds tested according to TestA-4 and Test20-4 approaches were higher than that of the ones tested with TestA-A approach. Compared to TestA-A approach, the LTE values of dormant buds were between 0.00 and 4.00°C in the TestA-4 approach and 0.00 and 2.77°C in the Test20-4 approach based on temperature changes. As a result, to achieve reliable, and consistent LTE results at DTA tests, it was determined that dormant buds should be brought into laboratory by keeping the temperatures at the sampling time, prepared for test at these temperatures and to start DTA test from these temperatures is a right approach.

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Many plants confront several environmental stresses including heat, water stress, drought, salinity and high-metal concentrations that are crucial in defining plant productivity at different stages of their life cycle. Nitric oxide (NO) and Silicon (Si) are very effective molecules related in most of them and in varied biochemical events that have proven to be protective during cellular injury caused by some stress conditions like water stress. In the current work, we studied the effect of Si and NO alone and NO + Si interactive application on the response of plants exposed to water deficiency and well-watered plants for the Milord apricot variety. Water stress caused a reduce in chlorophyll content, dry and fresh weight, leaf area, stomatal conductivity, leaf relative water content and nutrient elements, while it caused an increase in leaf temperature, leaf proline, leaf malondialdehyde (MDA) content and membrane permeability. Si, NO and Si + NO combination treatments under water stress conditions significantly decreased the adverse effects of water stress on leaf temperature, leaf area, dry and fresh weight, stomata conductivity, relative water content, membrane permeability, L-proline and MDA content. The shoot dry weight, chlorophyll content, stomata conductivity and leaf relative water content in Si + NO treated apricot saplings increased by 59%, 55%, 12% and 8%, respectively. Combined treatment (Si + NO) was detected to be more effective than single applications (Si or NO) on some physiological, biochemical, morphological and nutritional properties of apricot under water stress conditions.