Abstract
Drought stress deleteriously affects growth, development and productivity in plants. So, we examined the silicon effect (2 mmol) and proline (10 mmol) individually or the combination (Si + proline) in alleviating the harmful effect of drought on total phenolic compounds, reactive oxygen species (ROS), chlorophyll concentration and antioxidant enzymes as well as yield parameters of drought-stressed sugar beet plants during 2018/2019 and 2019/2020 seasons. Our findings indicated that the root diameter and length (cm), root and shoot fresh weights (g plant−1) as well as root and sugar yield significantly decreased in sugar beet plants under drought. Relative water content (RWC), nitrogen (N), phosphorus (P) and potassium (K) contents and chlorophyll (Chl) concentration considerably reduced in stressed sugar beet plants that compared with control in both seasons. Nonetheless, lipid peroxidation (MDA), electrolyte leakage (EL), hydrogen peroxide (H2O2) and superoxide (O2●−) considerably elevated as signals of drought. Drought-stressed sugar beet plants showed an increase in proline accumulation, total phenolic compounds and up-regulation of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) activity to mitigate drought effects. Si and proline individually or the combination Si + proline considerably increased root and sugar yield, sucrose%, Chl concentration and RWC, MDA and EL were remarkably reduced. The treatments led to adjust proline and total phenolic compounds as well as CAT and SOD activity in stressed sugar beet plants. We concluded that application of Si + proline under drought stress led to improve the resistance of sugar beet by regulating of proline, antioxidant enzymes, phenolic compounds and improving RWC, Chl concentration and Nitrogen, Phosphorus and Potassium (NPK) contents as well as yield parameters.
Highlights
We observed that root length and diameter, root and shoot fresh weights (g plant−1 ) of sugar beet plants under drought were considerably decreased (37, 40.9, 44.4 and 33.3%) compared with control plants (Figure 1A–D) as the main of the two seasons
Enough, that combination of Si + proline gives the maximum results of the above-mentioned traits without a difference when compared with control during both seasons
Antioxidant enzyme activities were elevated under drought to induce plant defense system and scavenge O2 − and
Summary
Sugar beet is an important industrial sugar crop and one of the most significant crops for sugar production, it is adjusted to the Egyptian environment and has an important position in winter crop rotation in all kinds of soils. Sugar beet needs a shorter period of productivity and consumes less water than sugarcane [2,3]. Many environmental stress factors affect the plant growth and productivity in various plants; biotic factors [4,5,6,7], salinity [8,9,10,11], heat [12], drought stress [13,14,15]. Drought is one of Antioxidants 2021, 10, 398.
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