CROP - LOGGING TECHNIQUE IN SUGARCANE
The ultimate aim is to ascertain a guide line for future nutritional research programme based on crop logging.
By Dr. S. M. Alam
Nuclear Institute of Agriculture
Jan 01 - 14, 2001
The average sugarcane yield in Sindh is very low. Recommendations for N, P and K requirements have been prescribed, but adequate attention to other nutrients has not adequate, and important nutrients may be limiting the optimum growth and yield of sugarcane. Besides adequate level of nutrients at different growth stages is also an important aspect of plant growth, which requires due consideration. Crop-logging may be of great help to determine the adequate levels of different nutrients for good plant growth and high yield. The concept of crop-logging was developed by Clements of USA for the growing of sugarcane in Hawaii, where the fertilizer requirements of this crop are greatly influenced by weather and climate.
The crop log is a record of the crop's progress from its start until harvest and is made up of certain physical and chemical measurement and observations which serve as a guide to its handling. Adequate nutrition of augarcane results in optimum growth and development of the plant with high sugar yield. The balance for the low sugar yield in Sindh is usually put on the existing varieties, with no considerations of the nutritional status. In order to obtain a guide line for planned research programme, it was essential to make a nutritional survey of the sugarcane crop of Sindh cane zones. The ultimate aim of this technique is to ascertain a guide line for future nutritional research programme based on crop-logging of sugarcane.
Eight months old sugarcane plants of four commercially grown varieties (PR-1000, BL-4, CP-68-1067 and L-116) were collected from the experimental farm of NIA, Tandojam and chopped into double budded sets of about 15 cm in length. These sets were then dipped in 0.8% benlate solution for 3 minutes before planting and then sown to desert sand beds of pot-house in the month of November. Six sets were sown to each bed measuring about 2.7% square meter. The beds were irrigated with tap water and after 20 days when the seedling had emerged almost in every variety, the following treatments were started. (1) Control (full Hoagland solution) (2) minus nitrogen (3) minus phosphorus and (4) minus potassium.
In the control bed, all the major and minor nutrient elements necessary for the growth of sugarcane plants were added as salts. In the minus treatments all the salts were added to the individual tanks except those containing N, P and K. There were two replicates of each treatment making a total of 32 beds. The beds were irrigated every week and the necessary salts were added to the tanks when necessary as determined from periodical analysis of the culture solution. The third fully expanded leaf from three plants of each variety were collected after 75 days of sowing and thereafter every monthly making a total of ten harvests. The fresh (two harvests) and dry weights of plant leaves were recorded and the samples were analyzed for N, P, K, Ca and Na contents. The deficiency symptoms of N, P, K were also recorded as and when they appeared. The N deficiency symptoms were most distinct, where plants were yellowish green in colour, the stalks were smaller in diameter and slight reddish colour developed on the dry lead portion of the stalk.
The plants had very little tillering in most of the varieties. Compared to control treatment the P deficient plants had much smaller and fewer leaves with deeper green colour. The most significant affect of inadequate P was its effect on tillering, and there were few tillers with slender stalks in most of the varieties. In the absence of K, the first symptoms of K-deficiency consisted of a retardation growth with distinctly slender stalks followed by a distinct yellowing of the leaves, which was accentuated at the tips and margins. This marginal yellowing was followed later on by death or firing of the affected areas, a condition also referred to as marginal scorch. The plants in the complete nutrient solution (control) were healthy, well branched and normal green in colour. The growth for about three months was not affected very much in the minus nutrient treatments, but the effects of the absence of particular nutrients became visible thereafter. The variety BL-4 produced the maximum leaf dry wt in all the treatments followed by L-116 PR-1000 and CP-68 in that order.
The analysis of the plant leaves at the earlier harvested showed no marked differences in the content of N, P, K of the leaves from the minus treatments compared with those from the control plants. At the later stages of growth, when N, P, K deficiency symptoms also appeared the analysis indicated that the deficient leaves contained relatively low quantities of the respective nutrients (NPK) as compared to the healthy (control) ones, which apparently resulted in the retarded growth of plants.
Nutrient requirements of sugarcane: The sugarcane crop has gained a considerable importance in the province of Sindh during the last fifteen years or so. It has now become one of the most promising cane crops of this region. With the establishment of sugar mills in the southern zone, there has been a phenominal rise in the average of this crop. Though the average has increased from 17000 acres at the time of independence to almost 24x105 acres now, yet the yield of cane and the recovery of sugar have remained the lowest in the world. The yield of sugar is hardly about one or two tons per acre as compared to 11 tons in Hawaii, about 7 tons in Java (Indonesia), 3.5 tons in Mauritius and Australia about 3.0 tons in Cuba, Philippines and India. The causes of such a poor yield have to be examined.
Balanced nutrition of cane plant results in good growth and high yield. Numerous attempts have been made to predict the nutrients requirement of sugarcane. These involved both soil and diagnostic tissue testing methods. Critical levels of different nutrients are estimated after intensive fertilizer experiments in the field and pots as well. Much emphasis has been given to diagnostic tissue analysis as a guide for fertilizer application in cane crop. Tissue analysis helps in knowing whether the crop is deficient in applying additional amounts of fertilizers. Visual symptoms develop only when the nutrient deficiency becomes acute and then it is too late to correct the same. Clements (1960 ) in Hawaii has developed a foliar diagnostic technique known as Crop-logging of sugarcane.
Crop logging aims at portraying all the important factors of plant physiology which the crop experience from the time it is started until it is harvested and in such a precise and simple manner that it can be used as a guide for the profitable production of cane and sugar. In this method plant samples are collected every 5 weeks from 3 months of age, analyzed and determined whether the crop needs additional fertilizers and the application of fertilizers influences both yield of cane and its wide quality in respect of sucrose content.
Clements (1960 ) in his crop-logging has established the critical levels of different nutrients, leaf N 2.2 to 2.5%, P. K, Ca and Mg contents of sheath expressed as percent sugar free-dry matter as 0.08% respectively. When the level of any of the above nutrient falls below the critical, additional fertilizers increase cane and sugar yields. He suggests that the sheath Mn content below 20 ppm is the possible range of deficiency and that above 150-200 ppm the toxic. For a one year crop in British Guyiana, Evans (1967) reported the 4th leaf lamina as suitable diagnostic tissue for all the essential nutrients. He established that during the "boom stage" of growth the leaf lamina of plant crop at 3 months and ratton at 2 months should contain 2.4-2.5% N. Phosphorus should be 0.21% throughout the growth period in plant crops as well as in rattons. Critical level for K is 1.25% in the dry matter during the active growth. While those for Ca and Mg are 0.13-0.15% Ca and 0.06-0.08% Mg respectively. He further suggests that adequate levels of different micro-nutrients in the leaf lamina are as follows:
Fe 5 ppm (values upto 80-100 ppm are normal), Mn 20 ppm (values upto 200 ppm are normal), Zn 15 ppm (values upto 50 ppm are normal), Cu 4 ppm (values upto 15 ppm are normal), B 1 ppm (values upto 10 ppm are normal), Mo 0.08 ppm (values upto 1 ppm are normal).
Adequate nutrition of cane results in optimum growth and development of the plant with high sugar yield. The balance for the low sugar yield in Sindh is usually put on the existing varieties, with no considerations of the nutritional status. In fact, inadequate nutrition is definitely one of the major factors causing the low yield of sugar. Inadequate literatures on the nutritional status of the existing varieties is one of the limitations in undertaking nutritional research. In order to obtain a guide line for planned research programme, it was essential to make a nutritional survey of the sugarcane crop of Sindh cane zones. The ultimate aim of this is to ascertain a guide line for future nutritional research programme based on crop logging.