Carbohydrate and nitrogen levels of 'carabao' mango shoots sprayed with potassium nitrate
1987
Quirol, P.T.
The leaf nitrate reductase activity (NRA) and carbohydrate and nitrogen levels of 'carabao' mango shoots were monitored in trees with varying responses to KNO3. The responses included flowering (FWR), flushing of sprayed shoots only (FLS), flushing of both sprayed and unsprayed shoots (WTF) and no response (UNR). Spraying of KNO3 increased NRA. Enzyme activity was highest on the day of spraying and steadily declined to the level of the control on the 7th, 6th, and 5th day, respectively, in FWR, FLS, and WTF and UNR. Control rates of NRA was highest in WTF, followed by FWR and FLS, and lowest in UNR. The induced rates of NRA were similar in FWR, FLS and WTF which were higher than UNR. The levels of starch, soluble sugars and protein N were highest in FWR and lowest in UNR. The FLS had carbohydrate and N levels close to FWR while WTF had lower values than FWR in most of the parameters measured. There was a marked decline in starch content in FWR starting 3 days after spraying in stems and on the 4th day in leaves. This reduction was more pronounced in profusely flowering trees than in slightly or moderately flowering trees. Potassium nitrate did not affect the other aspects of carbohydrate and nitrogen metabolism. The enhancement of NRA was independent of the leaf NO3 to the negative levels. It did not cause appreciable changes in both NO3 to the negative N and protein N contents of the sprayed shoots.
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