Sugarbeet Fruit Germination and Emergence under Moisture and Temperature Stress¹

Abstract

Poor fruit germination and emergence of sugarbeet (Beta vulgaris L.) due to moisture and temperature stress can limit satisfactory stand establishment. Our objective was to evaluate laboratory procedures which measure germination and emergence potential under moisture and temperature stress and to use these tests for development of fruit treatments for improving field emergence under stress conditions.Germination tests were conducted on blotter paper using polyethylene glycol 600 osmotic solutions to induce moisture stress. Emergence through a 2.5 cm layer of greenhouse soil mix (Ascalon sandy loam and peat, 1:1 V/V) was used to evaluate the effect of fruit treatments on emergence under moisture and temperature stress. The soil mix, initially at —1/3 bar matric potential, dried to —10 to —5 bar matric potential during the course of the test. Emergence through a 3.3 can layer of packed silica sand (3.5% water — wt/wt) was used to evaluate treatments under temperature, moisture and impedance stress tests conducted at 9, 15, or 26 C. Field trials were used to confirm results of laboratory tests.Germination of sugarbeet fruit decreased with increas. ing osmotically simulated moisture stress from 0 to —7 bar water potential after which no germination occurred. Increasing the moisture stress from 0 to —4 bar potential decreased the rate of germination, but not the final germination percent, while both rate and final germination percent decreased sharply as moisture stress went from —4 to —8 bars. Removal of the pericarp decreased the water requirement for germination at a given rate by 2 bars, indicating that the pericarp is a major factor limiting germination and emergence under moisture and temperature stress.Treatment of the fruit with 1.0 N HCI for 2 hours significantly improved germination and emergence under moisture and temperature stress conditions in laboratory and field trials. Excessive acid treatment damaged the true seed. The acid treatment did not improve the emergence where impedance was the major stress or in the absence of moisture and temperature stress. Temperature affects not only the rate and extent of germination, but also the moisture requirement. The sugarbeet fruit germination at —5 bar matric potential and 26 C was equal to that at —1 bar and 9 C.The germination of untreated fruits of eight cultivars ranged from 26 to 72% at —1 bar matric potential and 9 C, and from 6 to 20% at —5 bar and 9 C. Acid treatment improved germination of all cultivars, but low germinating cultivars were improved the most.

Sugar-beet seed steep treatments to improve germination under cold, wet conditions

“…Nevertheless, the net effect was sufficient to progressively reduce cortex density and water uptake and improve performance under cold, wet conditions (Table 2) . We found that steeping seed in 0 .3 M HCl for 2 h was adequate whereas 1 .0 M was found necessary before [2]. It may be that present seed is rubbed more thoroughly to leave less cortex ; inhibitor contents may have decreased as vigour has increased .…”

“…experiments where leachate pH was monitored, it became apparent that part of the acid was more difficult to remove than suggested by the 5-minute rinse used in earlier work [2] . We found five changes of water over 1 .5 h were needed -one explanation was that the acid had penetrated the fine, dry capillaries in the cortex and was then slow to diffuse back out .…”

“…Benefits were greater following a short steep in dilute acid [1,2] . In England none of these treatments have been exploited commercially due to the inability to steep large quantitites of seed, the prohibitive cost of fusicoccin and the seedling etiolation associated with gibberellin treatment .…”

The use of hydrochloric acid to improve the germination of sugar-beet seed

“…Recently, we confirmed that steeping sugar-beet seed in hydrochloric acid improved germination under cold, wet conditions [1,2,5] . The improvement in early growth was large enough to warrant further investigation .…”

Effects of planting dates, fertilization with N and irrigation mode on morphological and phenotypic traits of sugar beet seedlings

“…U našim agroekološkim uslovima setva se izvodi u julu i avgustu kada su temperature najveće a padavine najmanje, što znači da uspešna proizvodnja sadnica mora biti u uslovima navodnjavanja. Ako bi se u laboratorijskim uslovima odstranio perikarp semena šećerne repe količina vode za klijanje bi se višestruko smanjila (Akeson et al 1980).…”