Before nitrate nitrogen can be utilised by the plant and transformed into protein it must be reduced to NH2by an enzyme called nitrate reductase. Roots and shoots are both capable of nitrate reduction in most plants, and roots may reduce between 5 and 95% of the nitrate absorbed. As the amount of nitrate fertiliser increases, however, the capacity for reduction in the roots becomes a limiting factor and an increasing proportion of this nitrate is translocated to the shoots.Nitrate reductase activity decreases as leaves mature and, because the phloem mobility of nitrate is limited excess nitrate is stored in the cells. This accumulation of nitrogenous compounds increases susceptibility to disease and also reduces the synthesis and movement of carbohydrates and sugars.In sugar beet this will also increase levels of amino N.
Molybdenum is essential for good nitrate reductase activity, whilst Boron ensures efficient nitrogen utilisation.
When plants absorb excessive amounts of nitrogen the use of Growth Balancer ensures that the production of nitrate reductase is not limited by deficiency of molybdenum. Boron is also known to affect nitrogen metabolism and carbohydrate metabolism and is believed to enhance sugar transport. When crops are at all deficient in boron starch accumulates in the leaves and can no longer be metabolised. Boron can therefore enhance the sugar and starch contents of fruit and storage organs such as potato tubers and beet roots.
The onset of senescence is the plants normal mechanism to move nutrients, sugars and starches into the storage organs. When nitrogen levels are high senescence may be delayed and the process may not start early enough to be completed by harvest.
Growth Balancer can be applied 4-6 weeks before harvest to potatoes and sugar beet which have not started to senesce in order to enhance the movement of sugars out of the leaves and into the storage organs. In beet this application will also reduce the amount of secondary growth which frequently occurs late in the season and which pulls nutrients from the roots into the new leaf growth.
When the crop has reached full leaf cover applications of 2l/ha Growth Balancer will slow vigorous growth, which may render the crop more susceptible to disease and quality reduction.
10l/ha Growth Balancer should be applied to crops 4-6 weeks before harvest, if they have not already begun the process of senescence.