Interactions Of Nitrogen, Water With Light On The Growth Of Maize

Interaction of the plant growth with the factors of water, nitrogen and light is very closely. In order to provide theory basis and guidance for the agriculture production reasonably, the mechanism for the functions of water, nitrogen and light in the growth of plant need to be studied. In this thesis, effect of water, nitrogen and light on nitrate reductase activity, nitrite nitrogen, nitrogen content and biomass production in maize planted in pot and field experiments are discussed. The main results obtained in this study are as follows:(1) Nitrate reductase activity of maize grown in four different N-fertilizer sources was highest in leavers under high light and high fertilizer treatments, but it was lowest in roots under high light and low fertilizer treatments. The nitrate reductase activity of maize leaves and roots was higher with appropriate nitrate applications, but lower under low lighttreatments in other forms N-fertilizer sources especially ammonium fertilizer source.(2) Increasing the amount of ammonium fertilizer might enhance nitrogen uptake and assimilation in maize seedlings. Under the same conditions, the contents of nitrogen and nitrate of leaves in maize were lower, the amount nitrogen in maize was higher and the shoot biomass production was highest. In nitrate fertilizer sources, the contents of nitrogen and nitrate in maize were highest.(3) Under low light treatments, the nitrate reductase activity of maize leaves was only slightly affected, root nitrate reductase activity of maize was notably affected by the amount of water and nitrogen in soil. Under drought conditions and with a great of ammonium fertilizer application, the root nitrate reductase activity of maize was high. Under high light treatments, the nitrate reductase activity of maize leaves and roots were increased with the increase of the amount of irrigation water, but it reduced by axcessive irrigation water under the higher N-fertilizer treatments.(4) High light is useful to increase the leaves nitrate content in maize. The leaves nitrate content in maize was reduced under the appropriate amount of irrigation water and application of N-fertilizer, but it increased under the drought condition or axcessive irrigation water.(5) Under high light treatments, the shoot and root biomass production in maize were higher, and the root/shoot ratio was higher. Under lower light treatments, with the appropriate increase of the amount of application of nitrate fertilizer, the shoot and root biomass production in maize were increased and the root/shoot ratio was slightly affected.(6) The root/shoot ratio in maize was increased with the appropriate increase of the amount of irrigation water. Under high light treatments, the appropriate water efficiency made root grow well in maize.(7) The amount nitrogen in maize was increased with the increase of light. The amount nitrogen of seed in maize was increased and the amount nitrogen of stems and leaves in maize were reduced with the appropriate increase of the amount of irrigation water. The amount nitrogen in maize was reduced under the drought conditions or by axcessive irrigation water. The amount nitrogen in maize were increased with the appropriate increase of the amount of application of N-fertilizer, but under the drought conditions, were reduced by the great amount of application of N-fertilizer.(8) The biomass production in maize was increased with appropriate increase of the amount of irrigation water or application of N-fertilizer, affected notably by light, but reduced by axcessive irrigation water or application of N-fertilizer.