Leaf Necrosis in Rambutan (Nephelium lappaceum), its Causal Factors, Effect on Yield and Control Techniques

Transcription

1 Leaf Necrosis in Rambutan (Nephelium lappaceum), its Causal Factors, Effect on Yield and Control Techniques Didik Indradewa, Dja far Shiddieq, Bambang Hendro Soenarminto, Heri Supriyanto, Istiyarni and Tujiyanto Faculty of Agriculture, Gadjah Mada University, Yogyakarta 55281, Indonesia

2 Rambutan Tree Species: Nephelium lappaceum L. var. lappaceum Family: Sapindaceae (Soapberry)

3 Rambutan Fruits Cultivated primaily for its fresh fruit, but also canned in syrup, cooked for stewed fruit and jams

4 Introduction Rambutan fruits are native to the humid tropical regions of the Malaysian Peninsula in Southeast Asia Rambutan production occurs in Malaysia, Thailand, and Indonesia

5 Origin and area of Rambutan areas under cultivation to be 71,150 hectares in Thailand (448,500 tonnes); 43,000 plus hectares in Indonesia (199,200 tonnes); 20,000 hectares in Malaysia (57,000 tonnes) and 500 hectares in the Philippines.

6 Center of rambutan production in Indonesia

7 Fertilizers rate recomended For fruiting trees, 200 g N, 25 g P and 130 g K per tree per year. Maximum fertilizer rate is reached at 12 years, and should remain constant thereafter. No fertilizers are applied by farmers

8 Leaf necrosis In Indonesia climate is highly influenced by yearly monsoons, resulting in distinct wet and dry seasons During dry season, rambutan plant in drier area (Central Java, Yogyakarta and East Java) suffer of leaf necrosis Leaf necrosis is a specific symptom of K deficiency

9 Symptomp of necrosis in rambutan leaf

10 Problems Limited scientific-based information was available conserning the causes, its effect on crop yield and the appropriate control techniques.

11 Potassium Under drought conditions chloroplasts lose high amounts of K Potassium plays a central role in maintenance of photosynthesis and related processes.

12 For plants grown under low K, droughtstress will induce: 1. disturbances in stomatal opening, water relations, photosynthesis 2. induce ROS (reactive oxygen species) formation as : superoxide radical (O2 ), hydrogen peroxide (H2O2), and singlet oxygen (OH)

13 Cakmak, 2005

14 Reactive O2 species highly toxic causing membrane damage chlorophyll degradation responsible for development of leaf chlorosis and necrosis,

15 Purpuses of the experiments To determined the cause of leaf necrosis in rambutan trees To study the effect of leaf necrosis on fruit yield of rambutan To found out the techniques of controlling leaf necrosis of rambutan trees

16 Materials and Method First experiment Pot grown rambutan seedlings of cv. Rapiah of five month old, were placed in greenhouse of the Department of Agronomy Experimental Station Gadjah Mada University. Wind blower were used to generated a 44.2 m/min wind flow at 29.1 o C and 37.4 o C. Potassium chloride fertilizer was applied to both sets of pot at the rates of 0, 10, 20, 30 and 40 g/pot.

17 Second experiment Healthy and necrotic eight years old plants of rambutan cv. Lebakbulus were used for observations. The experiment were conducted at farmer garden at Salaman Central Java during the period of August 1996 to February 1997 Observations were done on : soil moisture content, relative water content, available soil K content, K content of leaves, percentage of leaves suffered of necrosis, fruit yield and yield component.

18 Third experiment The experiment were conducted on seven years old rambutan trees at farmer garden at Borobudur Central Java during the period of August 2006 to February The experiment was used a 4x4 factorial design replicated three times. The first factor was rate of K Cl consisted of four levels : 0, 125, 250 and 375 g/tree The second factor was rate of organic fertilizer consisted of four levels : 0, 17.5, 35.0 and 52.5 kg/tree. Observations were done on : soil conditions, percentage of leaves suffered of necrosis, fruit yield and quality of fruits.

19 Result and Discusion Experiment I Leaf necrosis was influenced by Relative Water Content (RWC) and K content in leaf. Relationship between K content and leaf water content with level of necrosis showed in equation : Nec = 25,61 10,47 K 0,22 RWC Nec : level of lef necrosis (%) K : K content of leaf (%) RWC : relative water content (%).

20 Experiment I leaf nekrosis flourished when content of K in leaf less than 1% and RWC less than 80% the sufficien content of K for the leaf of rambutan was between 1,10-1,39 %.

21 Experment II Healthy rambutan crop did not show any symptom of necrosis on their leaves, while suffering crop experienced necrosis almost half of their leaf area. Part of rambutan leaf suffering of necrosis was not able to do transpiration process

22 Experment II.. the broader area of necrosis, the lower amount of water and nutrition absorbed and the higher moisture and K left in soil. the relative water content and the content of potassium in leaves of necrotic plant were lower than those the healthy one. Reduction of fruits yield in necrotic rambutan was due to reduction in number of fruits per tree and also reduction in fruit size

23 Table 1. The effect of necrosis on soil, leaves, fruit yield of rambutan. Variables Healthy Trees Necrosis Soil Moisture Content (%) 16,6 b 18,0 a Rel Water Content of leaves (%) 82,6 a 77,4 b Available Soil K (me/100g) 0,80 b 1,54 a K content of leaves(%) 0,74 a 0,59 b Necrotic area on leaves (%) 0,00 a 46,5 b Number of fruit per tree 999,2 a 253,4 b Weight per fruit (g) 36,6 a 29,6 b Fruits yield per tree(kg) 36,57 a 7,50 b

24 Experiment III no interaction. Effect of organic manure and K Cl were presented separately.

25 Effect of organic manure maintained soil moisture content increased relative water content of leaves with linear relationship pattern improved cation exchange capacity with linear relationship pattern had a quadratic relationship with available K in soil with the optimum rate of about 47 kg/tree

26 Effect of organic manure. reduced the level of necrosis increased fruit yield of rambutan Increased the amount of fruits per tree. Fruit size and vitamin C content were not affected increased total soluble solid

27 Tabel 2a. The effect of organic fertilizer on soil caracteristics and leaf necrosis Variables Rate of organic fertilizer (kg/tree) 0 17, Soil moist cont (%) 17,41d 21,01c 28,89b 35,04a Rel water cont (%) 78,35d 80,99c 83,16b 85,53a CEC (me/100g) 14,24d 15,84c 18,03b 19,51a Available K (ppm)* 139,00 370,00 693,00 592,00 K cont leaves (%)* 0,37 0,25 0,49 0,31 Necrosis/leaf (%) 8,64a 8,61a 7,62b 7,11b Necrosis/tree (%) 12,78a 11,35b 11,01b 11,89ab

28 Tabel 2b. The effect of organic fertilizer on yield and yield components of rambutan. Rate of organic fertilizer (kg/tree) Variables 0 17, Nbr of bunchs/tree 29,83a 31,25a 33,00a 33,33a Nbr of fruits/cluster 8,95a 7,78a 8,75a 8,83a Fruit diameter (cm) 3,83a 3,95a 3,93a 3,86a Weight/fruit (g) 37,18b 42,88a 39,67ab 39,27ab Fruit yield/tree (kg) 8,35c 10,22b 11,75a 11,86a Tick of frt flesh(cm) 0,75ab 0,71ab 0,70b 0,78a Ttl slbl solid (%) 14,78b 14,17 15,50a 14,93ab Vit. C (mg/100g) 20,14a 20,15a 20,15a 20,15a

29 Effect of KCl did not have any effect on soil moisture and CEC Effect on potassium availability in soil and potassium content in leaves was not clear, reduced necrosis level in the leaves significantly.

30 Effect of KCl increased fruit yield of rambutan (with linier increase up to 375 g KCl/tree) due to: increasing of fruit bunches per tree, but was not because of increasing number of fruit per bunch and fruit size increased of fruit flesh thickness and total soluble solid, the content of vitamin C did not affected

31 Tabel 3. The effect of potassium fertilizer on soil caracteristics and leaf necrosis Rate of organic fertilizer (kg/tree) Variables Soil mst con(%) 24,17a 24,33a 24,74a 24,11a Rel wtr con (%) 67,00 ab 66,84b 67,69a 67,29ab CEC (me/100g) 16,91a 17,01a 16,89a 18,81a Avlabl K (ppm)* 139,00 109,00 153,00 102,00 K con leavs (%)* 0,37 0,34 0,36 0,34 Nec/leaf (%) 12,43a 8,88b 6,42c 4,25d Nec/tree (%) 14,84a 13,15b 11,07c 7,71d

32 Tabel 3a. The effect of potassium fertilizer on yield and yield components of rambutan. Variables Rate of orgnc fertilizer (kg/tree) Nbr bunc/tree 25,08c 25,50bc 38,00a 35,83ab Nbr frts/clstr 7,91a 8,53a 8,83a 9,03a Frt diam (cm) 3,77a 3,88a 3,87a 4,04a Weight/frt (g) 40,52a 41,30a 39,01a 38,17a Frt yield/tr(kg) 8,05c 9,82b 11,77a 12,53a Tik frt flh(cm) 0,67b 0,76a 0,76a 0,75a TSS (%) 13,60c 14,56b 15,15b 16,07a Vit. C (mg/100g) 20,15a 20,15a 20,14a 20,14a

33 Conclusions 1. Leaf necrosis started when potassium content and relative water content of the leaves were less than 1% and 80% respectively. The lower they were, the wider the symptoms appeared.

34 Conclusions. 2. Lower potassium content in leaf caused higher leaf necrosis and lower fruit yield. The reduction of fruit yield was around of 80%. Yield reduction was due to reduced number of fruit per tree, as well as fruit size

35 Conclusions. 3 Increasing of potassium fertilizer and organic fertilizer rate reduced the percentage of leaf necrosis and increased the fruit yield with the optimum rate of 460 g KCl per tree and 51 kg of organic fertilizer per tree.

36 Thank You