Water deficiency significantly affects photosynthetic characteristics. However, there is little information about variations in antioxidant enzyme activities and photosynthetic characteristics of soybean under imbalanced water deficit conditions (WDC). We therefore investigated the changes in photosynthetic and chlorophyll fluorescence characteristics, total soluble protein, Rubisco activity (RA), and enzymatic activities of two soybean varieties subjected to four different types of imbalanced WDC under a split-root system. The results indicated that the response of both cultivars was significant for all the measured parameters and the degree of response differed between cultivars under imbalanced WDC. The maximum values of enzymatic activities (SOD, CAT, GR, APX, and POD), chlorophyll fluorescence (Fv/Fm, qP, ɸPSII, and ETR), proline, RA, and total soluble protein were obtained with a drought-tolerant cultivar (ND-12). Among imbalanced WDC, the enhanced net photosynthesis, transpiration, and stomatal conductance rates in T2 allowed the production of higher total soluble protein after 5 days of stress, which compensated for the negative effects of imbalanced WDC. Treatment T4 exhibited greater potential for proline accumulation than treatment T1 at 0, 1, 3, and 5 days after treatment, thus showing the severity of the water stress conditions. In addition, the chlorophyll fluorescence values of FvFm, ɸPSII, qP, and ETR decreased as the imbalanced WDC increased, with lower values noted under treatment T4. Soybean plants grown in imbalanced WDC (T2, T3, and T4) exhibited signs of oxidative stress such as decreased chlorophyll content. Nevertheless, soybean plants developed their antioxidative defense-mechanisms, including the accelerated activities of these enzymes. Comparatively, the leaves of soybean plants in T2 displayed lower antioxidative enzymes activities than the leaves of T4 plants showing that soybean plants experienced less WDC in T2 compared to in T4. We therefore suggest that appropriate soybean cultivars and T2 treatments could mitigate abiotic stresses under imbalanced WDC, especially in intercropping.

Introduction: Magnesium is very important nutrient and performs a significant part in development and formation of many sink organs like roots and seeds. Furthermore, its fertilization significantly affects yield and numerous physiological mechanisms in different horticulture crop species. Moreover, its deficiency caused germination and reduction in horticulture crop stand. Nevertheless, its adequate concentration by foliar application plays important role in biochemical and physiological processes of plants like proteins synthesis, metabolism of carbohydrates, enzymes activation and energy transferring. Worldwide, many of our horticulture crops are facing low yield and quality problem due to fertilizer application at inadequate rate. The current review focuses on the impact of foliar applied Mg on some important cultivated horticultural crops (sugar beet, tomato, banana, potato, spinach, cauliflower, cassava, garlic, green case, potus, cucumber and grapes). Review results: Our extensive review has demonstrated that magnesium is very important factor limiting horticulture crop production but its negative impacts can be reduced by foliar application of magnesium. Foliar application of Mg can be recommended for correcting deficiencies because foliar sprays have no long term residual effect and every time fresh applications must be given to each crop. Moreover, amount depends on the nutrient status of crop and soil.

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A half-root stress is a half portion of the root system exposed to treatment while the remaining half portion kept under normal conditions. A half-root stress including half-root drought stress, half-root nutrient stress, and half-root salinity stress has become a general approach to improve plant performance and adaptability. Plants produce some chemical signals in stressed part of root, and other parts sense these signals to improve the acclimation and adaptive responses to environmental stresses. Plants adapt the compensatory functions and discriminate the systemic and local regulatory mechanisms, but the understanding of these mechanisms is controversial. Chemical signals (Abscisic acid, sap pH, cytokinins, content of malate, amino acid, and ureide) have been involved in root to shoot signaling under half-root stress. Furthermore, naturally appeared half-root stress in intercropping systems could be an additional attribute of half-root stress approach. Therefore, much more study is required to elaborate its acceptability in intercropping. In this review, we summarized the current knowledge and identified some key future researches areas regarding half-root stress approach. ARTICLE HISTORY

Zinc (Zn) is a key mineral nutrient for plant and human growth and its deficiency can reduce the plant growth and development, however; agronomic bio-fortification can cure plant and human Zn deficiency. By using different Zn fertilization approaches, this study investigated the role and its impact on phenology, growth and yield of maize during two growing seasons 2015 and 2016. The treatments comprised of: no Zn application (ZnC 0 ), basal application of 10 kg ZnSO 4 .7H 2 O ha -1 (ZnB 1 ), basal application of 15 kg ZnSO 4 .7H 2 O ha -1 (ZnB 2 ), foliar application of 1% solution of ZnSO 4 .7H 2 O ha -1 (ZnF 3 ), foliar application of 1.5% solution of ZnSO 4 .7H 2 O ha -1 (ZnF 4 ) applied to two hybrids of maize (YSM-112 and DK-6525). The maize hybrid DK-6525 showed superiority in term of growth and yield than YSM-112. The ZnF 4 brings early emergence, tasseling and silking that resulted in early crop maturity. However, ZnB 2 improved crop growth rate, grain yield and Zn concentration in maize grain by 44, 11.39 and 33.24%, respectively than ZnC 0 (control). Regression model indicated that each 1 g increment in 1000-grain weight improved the grain yield by 0.01 and 0.16 t ha -1 of YSM-112 and DK-6525, respectively. Conclusively, it is concluded that DK-6525 with ZnB 2 is suitable for optimal growth and yield of maize and would also be helpful to optimize the yield and Zn concentration of maize. Key words: Basal and foliar application. Bio-fortification. Growth and yield. Maize hybrids and zinc fertilization. ResumoO zinco (Zn) é um nutriente mineral chave para o crescimento de plantas e humanos, e sua deficiência pode reduzir o crescimento e o desenvolvimento das plantas; bio-fortificação agronômica pode curar a deficiência de Zn humano e vegetal. Utilizando diferentes abordagens de fertilização com Zn, este estudo investigou o papel e seu impacto na fenologia, crescimento e produção de milho durante duas safras 2015 e 2016. Os tratamentos foram compostos por: sem aplicação de Zn (ZnC 0 ), aplicação basal de 10 kg de ZnSO 4 . 7H 2 O ha -1 (ZnB 1 ), aplicação basal de 15 kg de ZnSO 4 .7H 2 O ha -1 (ZnB 2 ), aplicação foliar de solução a 1% de ZnSO 4 .7H 2 O ha -1 (ZnF 3 ), aplicação foliar de solução a 1,5% de ZnSO 4 .7H 2 O ha -1 (ZnF 4 ) aplicado a dois híbridos de milho (YSM-112 e DK-6525). O híbrido de milho DK-6525 apresentou superioridade em termos de crescimento e produtividade que o YSM-112. O ZnF 4 traz emergência precoce, pendoamento e silagem que resultaram em maturação precoce da cultura. No entanto, o ZnB 2 melhorou a taxa de crescimento da cultura, a produtividade de grãos e a concentração de Zn no grão de milho em 44, 11,39 e 33,24%, respectivamente, do que ZnC 0 (controle). O modelo de regressão indicou que cada incremento de 1 g no peso de 1000 grãos melhorou o rendimento de grãos em 0,01 e 0,16 t ha -1 de YSM-112 e DK-6525, respectivamente. Conclusivamente, conclui-se que o DK-6525 com ZnB2 é adequado para o crescimento e produção ideais de milho e também seria útil para otimizar o rendimento e...