Cane Height Research Articles

Leaf nitrogen — sodium ratio in sugarcane clones and its associations with other parameters at grand growth period

Leaf N/Na ratio had a range of 3.64 in CP 44-101 to 6.09 in Co 6806 as per variety mean and their differences were significant. The wide variation of leaf N/Na ratio was between 2.54 in Co 1148 at 7 months to 7.86 in CoA 7601 at 4 months. High leaf N/Na ratio were observed in Co 6806, Co C 671, Co 7508, Co 7204, Co617, Co A 7601, Co 7201,Co 7717, Co 740, Co 853, Co 6304, while clones recorded low N/Naratio were CP 44–101, Co 62399, Co 1148, Co 975, Co 7704, H 50–7209, Co 997, Co 62101, Co 62175, Co J 64 and Co 775. Statistically significant decreas & of leaf N/Na ratio between stages were observed from 6.21 at 4 months to 3.42 at 7 months. The interactions-between clones x stages were also significant at 0.1 % level. The associations of leaf N/Na ratio were significant and positive with leaf N/P, N/K, N/Ca, N/Mg, N/S, N/C1, N/ Si ratios, sucrose % juice at 10 and 12 months, cane yield at 10 and 12 months, sugar yield at 8, 10 and 12 months, cane volume, cane height, cane thickness, cane weight, harvest index-sugar yield-8,10 and 12 months both on fresh weight and dry weight basis. There was a significant negative association between leaf N/Na ratio and leaf cations minus anions. However, leaf N/Na ratio had no effect on at any one stage with leaf cations/anions ratio, sheath N/P, N/K, N/Ca, N/Mg, N/S, N/C1, N/Na, N/Si, cations/anions ratio, cations minus anions, internodes numbers, stalk numbers, cane density, culm bulk density, harvest index-cane yield, harvest index-CCS %, harvest index-sucrose % juice-10 and 12 months both on dry weight and fresh weight basis.

Response of sugarcane genotypes to water deficit stress

Drought is one of the major constraints for sugarcane cultivation, which necessitates the development of drought resistant varieties. The drought situation prevailed at Coimbatore (India) during 2003 was utilized to study the performance of 97 high sugared genotypes under water deficit situation. Cane formation was observed only in 55 clones showing the impact of drought on cane growth and susceptibility of high sugared clones to water deficit stress. Mean values of all the traits were lower and CV higher( except for cane diameter) under drought. Drastic reduction in single cane weight (64.16%) mainly through reduction in cane height (48.79%) affected cane yield under drought conditions, while juice quality traits were less affected in the high sugared clones studied. A wide range in sucrose content in the high sugared clones under drought indicated the need to identify stable high sucrose types among the high sugared clones. Six clones performed better for sucrose content under water deficit stress and showed steady performance under normal and drought conditions. Seven clones combining better yield and quality were identified as potential sources for breeding for drought resistance and for evaluation to identify promising cultivars suitable for drought prone areas. Large scale screening of genetic stocks for drought resistance is suggested to develop an effective breeding strategy for drought resistance.

Investigation of sugarcane genetic stocks for leaf blade nitrogen-magnesium ratio at grand growth period and its associations with nutrients ratios, yield components, sucrose and yield of cane and sugar

At grand growth period, thirty sugarcane genetic stocks were studied for leaf blade N/Mg raio. Differences of leaf N/Mg ratio among clones, among stages and interaction between clone x stage were significant statistically at 0.1 % level. According to clone mean, the lowest and the highest leaf N/Mg ratio were 7.00 in Co 62399 and 11.43 in CoC 671. The wide range of leaf N/Mg ratio was in between 5.50 in Co 62399 at 4 months to 15.14 in Co 775 at 7 months. Clones CoC 671, Co 7712, Co 775, Co 7304, NCo 310, CoA 7601, Co 6806, Co 997, POJ 2878, and Co 7717 had recorded high leaf N/Mg ratio, while low leaf N/Mg ratio was observed in Co 62399, CP 44-101, Co 678, Co 7704, H 50-7209, Co 419, Co 62175, Co 6304, Co 1148 and Co 740. with the advancement of the age of the crop, leaf N/Mg ratio increased from 7.47 at 4 months to 11.49 at 7 months. The significant positive associations of leaf nitrogen-magnesium ratio were observed with leaf N/P, N/K, N/Ca, N/S, N/Cl, N/Na, N/Si, cations/anions ratio, sheath N/K, N/Ca, N/S ratios, sucrose% juice-8, -10, -12 months, harvest index-sucrose % juice and harvest index-C.C.S. %. There was a significant negative association between leaf N/Mg ratio and harvest index-cane yield. But leaf N/Mg ratio had no association with leaf cations minus anions, cane and sugar yield, stalk numbers, cane volume, cane density, cane height, cane thickness, cane weight, culm basic density and harvest index-sugar yield.

The effect of cane length on the haptic perception of height

Purpose: The purpose of this investigation was to determine whether the ability to haptically perceive object height is a function of the length of cane being wielded by blindfolded individuals.Method: Fifteen sighted females between the ages of 18 and 25 years volunteered to participate in the study. Five different heights of wooden blocks were haptically explored with four different cane lengths (0.92, 1.22, 1.37 and 1.67 m), cane length order being randomized across 2 days of testing. Subjects were asked to report whether the explored block's height was taller, shorter, or equal to that of a previously presented standard block. The percentages of correct judgments for each cane and block height combination were subjected to statistical analysis.Results: The analysis revealed significant main effects for cane length, F (3, 42) = 9.47, p < 0.0001, and block height, F (4, 56) = 17.69, p < 0.0001. The interaction of cane length and block height was not significant, F < 1. The accuracy of haptic perception improved with decreased cane length and increased difference in height from the standard block.Conclusion: Contrary to previous research on haptic perception in which probe length was found not to affect judgment accuracy, the present study found a marked influence of cane length on perceptual accuracy. This finding indicates that length is an important property that should be taken into account when prescribing canes for the visually impaired.

Effect of sustained sodic and saline-sodic irrigation and application of gypsum and farmyard manure on yield and quality of sugarcane under semi-arid conditions

A field experiment was conducted for 10 years (1989–1990 to 1998–1999) to study the effect of long-term irrigation with sodic and saline-sodic waters in the presence and absence of amendments on soil properties and their influence on growth, yield and quality of sugarcane on a well-drained sandy loam Typic Ustochrept soil. Irrigation water treatments included: a good quality water (CW), sodic water (RSC, 10 me l −1) and saline-sodic water (RSC, 10 me l −1 and EC, 3 dS m −1). Two amendments viz. FYM at 20 t ha −1 every year and gypsum applied with each irrigation to neutralize 7.5 me l −1 of RSC, were superimposed on these water treatments. Long-term irrigation with sodic and saline-sodic waters increased pH, EC and ESP of the soils. The harmful effects were relatively severe under saline-sodic irrigation. The cane yield and yield contributing parameters (cane height, average number of millable canes and cane thickness) decreased significantly over the years under sodic and saline-sodic irrigations. The beneficial effect of gypsum was more pronounced in increasing cane yield under sodic (30%) compared to saline-sodic irrigation (13%). On the other hand, FYM was more effective under saline-sodic (38%) than under sodic water irrigation (23%). The significant complimentary effects of both the amendments applied together were observed only under sodic irrigation. Under saline-sodic irrigation, both the amendments applied together were at par with FYM treatment but significantly better than the gypsum treatment. The percent commercial cane sugar (% CCS) significantly decreased under these treatments and had the lowest values under saline-sodic irrigation in most years. These irrigations also significantly increased the EC and Na, Cl and SO 4 content of the juice. The harmful effects of sodic and saline-sodic irrigation became severe in case of sugar yield over the years. Compared to 12.2 t ha −1 under CW irrigation, sugar yield was 10.2 and 8.3 t ha −1 after the first year and it further decreased at 0.29 and 0.18 t ha −1 per year under sodic and saline-sodic irrigation, respectively. The beneficial effects of the amendments in improving % CCS and sugar yield were similar to those observed in case of cane yield. Complimentary effects of these amendments in improving sugar yield were observed under sodic irrigation (12.3 t ha −1). In case of saline-sodic irrigation, sugar yield under the FYM treatment (10.8 t ha −1) was at par with gypsum plus the FYM treatment but was significantly higher than under the gypsum treatment (9.0 t ha −1). The results of the study suggest that sustainable cane and sugar yields with good quality juice can be obtained by applying gypsum/FYM or both under sodic and only FYM under saline-sodic water irrigation.

Biomass analysis and selection of sugarcane genotypes for drought tolerance

In a completely randomized greenhouse pot trial, 26 sugarcane genotypes were evaluated under irrigated and water stress conditions during the formative growth phase (90 – 117 days after planting). The evaluation was based on visual assessment at 117 days after planting and measuring agronomical parameters of cane, leaf, root and biomass over four time intervals, viz. 90, 101, 109 and 117 days after planting. An ANOVA showed that the genotypes possessed high degree of diversity, in the selection process for drought tolerance. The interaction, genotype x water treatment, was highly significant for cane height, cane girth, root length, root fresh weight, root bulk density, biomass fresh weight and biomass dry weight. At the formative stage, cane height and cane girth were the only practically viable parameters; best reflected by biomass dry weight, where correlation coefficient was (r = 0.517) and (r = 0.314) for cane height and girth, respectively. The 26 genotypes were classified into three categories in response to water stress: 5 tolerant, 11 moderate and 10 sensitive. Visual evaluation matched the evaluation based on biomass analysis in 16 cases, nearly matched in 9 cases and differed in 1 case. Visual evaluation is fast, inexpensive and relatively accurate and it may be a useful predictor for drought tolerance in screening large number of genotypes. However, more objectively, the procedure highlights the importance of biomass analysis in the evaluation of reasonable number of genotypes in response to water stress. The study allowed for selecting drought tolerant sugarcane genotypes suitable for cultivation in Ramu Valley and Morobe Province of Papua New Guinea.

Does soil texture influence the distribution of the greyback canegrub, Dermolepida albohirtum (Waterhouse) (Coleoptera: Scarabaeidae), in the Burdekin River sugarcane growing area?

A series of experiments was undertaken to examine the effect of soil type on the spatial distribution of greyback canegrub in sugarcane in the Burdekin region of Queensland. These experiments examined spatial distribution at a district level as well as within individual fields, using both field and laboratory experiments. The studies concluded that soil type affected canegrub distribution both within fields and within the Burdekin district. However, the mechanisms affecting the distribution at each level were very different. At a regional or district level the preference of greyback canegrub for sandy delta-type soils over soil with higher clay content was hypothesised to be the result of preferential oviposition and improved larval survival in sandy soils over soils with a high clay content. At the field level, cane height was thought to be the primary reason for the patchy distribution of damage, with taller areas being damaged in preference to shorter areas. As all cane is planted or harvested at the same time in each field, differences in cane height between damaged and undamaged areas were thought to be the result of differences in soil type.

Productivity, quality and nutrient balance in spring sugarcane (Saccharum spp. hybrid complex) under organic and inorganic nutrition

An experiment was conducted during spring season of 2008-09 and 2009-10 on sandy loam soil at Pusa to as- sess the effect of farmyard manure and fertilizer levels on sugarcane ( Saccharum spp. hybrid complex). The ex- periment was laid out in factorial randomized block design and replicated thrice with two FYM viz., 0 and 20 tonnes/ha and four fertilizer levels viz., F , 150 + 37.1 + 49.8, RDF; F , 150 + 43.6 + 66.4; F , 200 + 43.6 + 83.0 1 2 3 and F , 200 + 54.6 + 99.6 kg N + P + K/ha. Application of 20 tonnes FYM/ha to sugarcane recorded significantly 4 higher mean growth (tillers, 1,70,200/ha; cane height, 208.9 cm; drymatter accumulation, 33.3 t/ha), yield at- tributes (millable canes, 1,13, 600/ha; cane diameter, 2.18 cm) and cane yield (87.5 t/ha) over no FYM. An in- crease of 16.2% in cane yield, 26.31% in net return, 8.5% in benefit: cost ratio and 15.6% in sugar yield was no- ticed with FYM over its control. FYM @ 20 tonnes/ha registered an increase of 20.9% in N uptake, 20.3% in P up- take, 20.2% in K uptake, 10.0% in available N, 23.3% in available P and 6.4% in available K over no FYM. Net gain of N (65 kg), P (6.1 kg) and K (31 kg) were also highest in FYM added plots. Crop receiving 200 + 54.6 + 99.6 kg N + P + K/ha gave significantly higher tillers (1,83,800/ha), cane height (213.8 cm), drymatter (34.5 t/ha), cane diameter (2.22 cm) and number of millable cane (1,20,800/ha) though, it was statistically at par with 200 + 43.6 + 83.0 kg N + P + K/ha. There was an increase in cane and sugar yield with each successive increase in N + P + K level from 150 + 37.1 + 49.8 kg/ha to 200 + 43.6 + 83.0 kg/ha. Increasing N + P + K levels from F to F signifi- 1 3 cantly increased the net returns. However, further increase to F level did not proved profitable option. Fertilizer 4 application increased the N uptake from 164 to 238 kg/ha, P uptake from 14.9 to 21.9 kg/ha and K uptake from 191.3 to 277.6 kg/ha. Significant increase in available N status was recorded with an application of 200 + 43.6 + 83.0 kg N + P + K/ha. However, available P status in post harvest soil increased significantly with each successive increase in fertilizer up to highest levels i.e. 200 + 54.6 + 99.6 kg N + P + K/ha. Available K status was the highest (121 kg K/ha) at 200 + 54.6 + 99.6 kg N + P + K/ha though it was on par with 200 + 43.6 + 83.0 kg N + P + K/ha. Net gain of N, P and K were progressively increased with increase in N + P + K levels from 150 + 37.1 + 49.8 to 200 + 54.6 + 99.6 kg/ha.

Effect of Azotobacter and Azospirillum inoculation under graded levels of nitrogen on growth and yield of sugarcane (Saccharum oflcinarum)

A field experiment conducted during 1990-91 to 1992-93 with sugarcane (Sacchnrum officinarum L.) indicated that application.of graded levels of nitrogen along with inoculation of 2cultures increased the cane and sugar yields to the extent of 7.30 and 0.78 m tonsha respectively compared with the uninoculated control. The gemination. tillering, number of millable canes, girth and cane height were also improved due to Azotobacter and Azospirillum culture combination. Maximum response was observed in Azotobncter + Azospirillum culture with nitrogen. There was a saving of fertilizer N to the extent of 25-50 kgha and im- provement in soil properties.

Variability in sugarcane under rainfed condition

Fifteen sugarcane varieties of early and mid late maturity group were taken to study variability for quantitative, biochemical and juice quality characters under rainfed condition. Quantitative characters like germination percentage, number of shoots, leaf area index in June,cane height, number of millable canes, single cane weight and cane yield recorded moderate to high coefficient of variation, heritability and genteic advance. Among biochemical parameters proline content also showed high values of coefficient of variances and heritability. Hence, while selecting varieties tolerant to rainfed condition, these quantitative characters as well as proline content in leaf may be considered. The numerical estimates of genetical parameters for cane diameter, chlorophyll content and sucrose per cent juice were comparatively low.

An IPM module for the management of major insect pests of sugarcane in Indian subtropics

This paper describes the evaluation of some environmentally sound tactics developed for raising insect-pests damage free sugarcane crop in subtropical India. Six ecology based approaches were employed: timing irrigation and urea application, mechanical removal of damaging stages of pests and crop residues, earthing up, propping of cane stalks, liberation of egg parasitoid (Trichogramma chilonis) and foliar N application. Effects of these were determined on (i) incidence and intensity of four major insect pests namely, shoot borer (Chilo infuscatellus), top borer (Scirpophaga excerptalis), stalk borer (Chilo auricilius) and black bug (Cavelerius sweeti), (ii) crop growth function , (iii) control efficiency system and (iv) yield and quality of a number of commercial cane cultivars. Timing irrigation (10 day interval) and application of recommended dose of urea and earthing up during formative phase helped the crop escape shoot borer attack as also improved crop vigour in terms of increase in cane height and millable cane number, which ultimately contributed to higher cane yield than that obtained with insecticide treatment. The timely mechanical removal of top borer infested shoots or its egg masses and adults helped reduce the incidence of most damaging third brood alone by over 50 percent in all the cultivars studied. Apart from being completely safe to the environment the technique involves 3-4 times less (Rs. 150-250/ha) expenditure than the chemical treatment ( Rs. 1000-1500/ha ) and may find easy practicability in areas where labour is plentiful and inexpensive and on small family holdings. Innundative releases of egg parasitoid during July-October and the crop production practices like earthing up and propping of cane stalks which help avoid lodging could curtail stalk borer infestation adequately. The incidence and intensity of black bug in ratoon crop was also reduced between 50-70 percent with a concomitant increase in shoot height simply by removal of plant crop residue and foliar N applications. The cumulative use of these tactics resulted in reduced pest damage (below economic injury level), significantly increased yield (22-36% improved productivity), reduced costs of pest control, conservation of natural enemies maintaining resource quality, avoiding environmental and other risks to human and animals, and helped generate employment for poor and needy (mechanical control of top borer insect).

Influence of seed rates and row spacings on the growth and yield of late planted sugarcane

A field experiment was conducted to see the effect of seed rates and row spacings on the growth and yield of late planted sugarcane at Regional Research Station, Kheri (Sangrur) during 1995–96 and 1996–97. Pooled data of plant and ratoon crop on cane yield, tillers, millable canes and cane height revealed that significantly higher cane yield was obtained from the crop planted with the seed rate of 75,000 three budded seed setts/ha. It might be due to more tillers, millable canes and cane height. Maximum cane yield was recorded under the 75 cm spacing which was at par than those obtained under the row spacings of 60:30 and 120:60. The lowest cane yield was obtained under the row spacing of 90 cm. It indicated that pair row spacings of 60:30, 120:60 and 120:30 found superior in producing cane yield as compared to regular 90 cm row spacing.

Studies on variation in interspecific hybrids ofSaccharum

The extent and pattern of variation were studied in F1 population of improvedS. officinarum xS. spontaneum and commercial hybrids xS. spontaneum obtained from six crosses. The study revealed the superiority of all the crosses for cane population and presence of substantial variability for further effective selection and utilisation. Hybrid progenies were in general thin. High heterotic vigour was observed for cane height which will be of use to maintain yield potential. Mean performance of the crosses for single cane weight and H.R. Brix was low which needs further improvement. While crosses involving commercial hybrids as pistil parent like CoC 671 x PIS 38 and Co 86010 x PIS 38 were superior for cane population and H.R. Brix, crosses namely PIO 88-110 x PIS 44 and PIO 88-94 x IND 82-319 were superior for cane yield. In general, clones with high number of millable canes, moderate Brix, good vigour and medium thick canes were also observed which can be further exploited.

Assessment of the contribution of legumes to the nitrogen nutrition of sugarcane

Field trials were conducted to assess the contribution of legumes to the nitrogen nutrition of sugarcane at the up-land sugarcane experimental field of the National Cereals Research Institute Farm, Badeggi (9°45'N, 06°07'E) in the Southern Guinea Savanna ecological zone of Nigeria in the 1997 and 1998 wet seasons. The four treatments tested consisted of sole-planted chewing cane, and chewing cane intercropped with soybean (TGM 579), Sesbania rostrata and cowpea (Ife brown). The treatments were laid out in a randomised complete block design with three replications. The legumes were ploughed into the soil at 12 weeks after sowing (WAS). At 2 months after sowing, cane intercropped with cowpea generally recorded lower values for cane height, tiller number and crop vigour, while the sole-planted cane crop gave the highest values for each of these parameters in both years. However, at 4 and 10 months after planting and at harvest (1, 6 and 9 months after the legume incorporation) sole-planted cane recorded significantly lower cane height, single stalk weight and crop vigour in 1997 and 1998. Among the intercropping treatments, cowpea and sesbania had almost similar effects on the cane in terms of crop vigour, cane height, single stalk weight and cane yield (t/ha), being better than the sole-planted cane and intercropping with soybean.

Performance of sugarcane genotypes grown under sodic soil and water conditions

An experiment was conducted to evaluate the effect of residual sodium carbonates (RSC) of irrigation water on the growth and yield of sugarcane grown on sierozem light textured alkaline soil with sodic ground water and to study the performance of some promising sugarcane genotypes under these conditions. Treatments consisted of five levels of irrigations water viz RSC 2.8, 6.5, 12 me l −1 and RSC 6.5 and 12.0 me l −1 fully amended with gypsum. Plant and ratoon crops of eight genotypes of sugarcane were harvested. Cane yield and yield attributing characters like cane height, number of internodes per cane and number of millable canes were recorded. Juice quality viz percent juice extraction, percent sucrose, and commercial cane sugar (CCS%) in juice were determined at the harvest of crop. For both plant and ratoon crops, the average cane yield of all the genotypes of sugarcane and cane yield attributing characters decreased significantly with the increase in RSC of irrigation water to 6.5 and 12.0 me l −1 (35% and 51% decline in the average cane yield for plant crop). For ratoon crop, the corresponding decrease in the average cane yield was less than the plant crop (only 14% and 21%). Amending RSC with gypsum increased the yield in all genotypes. The cane yield of various genotypes obtained under amended RSC with gypsum treatments were almost equal to the yield obtained under RSC 2.8 me l −1 treatment (89% to 92% average cane yield for plant crop and 93% to 96% for ratoon crop). The effect of RSC of irrigation was variable for different genotypes (for example, for the plant crop of CoH 97, 65% and 76% and for CoH 108, 9% and 20% decline in the cane yield was observed with the application of high RSC irrigation water). As compared to plant crop, the ratoon crop of all genotypes recorded higher average cane yield and lesser decline in the cane yield with the application of high RSC irrigation water. Average juice extraction % decreased from 40.5% to 35.8%, and sugar yield decreased significantly (5.61 to 2.91 t ha −1 for plant crop and 6.18 to 5.38 t ha −1 for ratoon crop) with the increase in RSC of irrigation water, and amending RSC with gypsum increased the juice extraction % and sugar yield per unit area.

Calcium Sulfate Soil Amendment Reduces Incidence of Phytophthora Root Rot in Raspberry

Phytophthora is a debilitating root disease of many crops, and limits raspberry production in much of the world. Two fungicides are labeled for use against Phytophthora on raspberries in North America, but they are not effective when disease pressure is severe. We were interested in the effect of preplant soil amendments such as composts, fertilizers, gypsum and limestone on the incidence of Phytophthora in red raspberries. Various amendments were incorporated simultaneously at two sites prior to planting raspberries. Both sites had identical soil, but one had a known history of P. fragariae var. rubi and the other had no history of raspberry production. Differences in survival and plant growth of `Heritage' among fertilizer (ammonium nitrate, phosphorus acid), compost, gypsum and lime (calcitic or dolomitic) treatments were small in the uninfested site, whereas differences were large in the infested site. Gypsum (CaSO4) treated plots had higher yields and greater cane diameter, density, and height compared to control plots after 2 years. Plants in compost amended plots exhibited the most severe disease symptoms; liming had little effect. In a second field experiment, various sources of calcium and sulfate were compared in an infested site. As before, plants in calcium sulfate-amended plots performed better than plants in control plots or in plots amended with sulfur or potassium sulfate. In a greenhouse experiment using infested soil and artificial flooding, calcium sulfate also reduced disease incidence in `Titan' compared to unamended soil. Data from these three experiments suggest that gypsum could be used in an integrated approach to Phytophthora management in raspberries, and perhaps other crops as well.

Variability for quantitative traits in exotic hybrid germplasm of sugarcane

The foreign hybrid collection of sugarcane germplasm comprising 399 clones representing 10 geographical groups, was evaluated for nine yield and quality characters, in relation to their place of origin. Discriminant function analysis showed that all the nine variables contributed significantly to the discrimination of the groups, the maximum contribution being cane height. The overall percentage of correct classification was only 48%, with a range from 32% to 73% with respect to individual groups. This suggests an underlying genetic similarity among the groups, which stem largely from their common genetic base. The exceptions were the Hawaii and Mauritius groups, which had distinct identities. The Hawaii group was the most productive group, having maximum yield and sucrose potential. The Puerto Rico group was the best source for juice sucrose. Australian varieties bred for high juice quality did not show the expected level of juice sucrose in the present study. The use in breeding programmes of Hawaiian varieties, which have a broader genetic base and high yield and quality potential, might impart better productivity to commercial varieties.

Preplant Soil Amendments influence the Incidence of Phytophthora Root Rot in `Heritage' Red Raspberry

Phytophthora is a severe root rot disease in most raspberry production regions throughout the world. Disease control options are limited to raised bed culture and fungicide applications. Few Phytophthora-resistant varieties are available that have commercial quality. Little is known about how soil amendments (i.e., composts, fertilizers, and limestones) influence Phytophthora control in raspberry. We evaluated the effects of preplant soil modification on the incidence of Phytophthora root rot in red raspberries. The experiment was conducted simultaneously at two sites to differentiate between the nutritional value of the amendments and the disease control value. One site has a known history of Phytophthora and a the second site is assumed to be free of the causal organism. Raspberry plant growth and fruit yield measurements were taken for all treatments. Preplant soil application of Gypsum (CaSo4) and post-plant applications of phosphorous acid sprays (H3PO3) had the greatest fruit yields compared to all other treatments in the Phytophthora-infested site. Gypsum-treated plots had greater cane diameter, cane height, and cane density compared to the control plots on the Phytophthorainfested site. A second experiment was conducted to further investigate the use of gypsum for control of Phytophthora in raspberries. Field soil was collected for use as potting medium from each of the aforementioned sites and pathogen free `Titan' plants were established in the greenhouse. After subsequent floodings, gypsum-treated soils delayed foliar disease symptoms compared to the control plots. At the end of the experiment, the control plants had 100% foliar disease symptoms and gypsum-treated pots had 33% disease symptoms. This study suggests that gypsum could be used in an integrated approach to Phytophthora management in raspberries. Future research should identify minimal effective rates of gypsum, examine other calcium sources, and determine effectiveness in other fruit crops.

Response to indirect selection in ratoon of sugarcane seedlings

Effectiveness of indirect selection criteria for brix yield based on 4 primary characters (number of millable canes per stool, NMC), cane diameter, cane height, and hand refractometer brix (HR Brix) was studied. A general index involving these traits was studied in 3 populations of ratoon seedlings. Selection based on number of millable canes was best, followed by selection based on selection index and cane height in ratoon crop. The differences in mean performance in ratoon crop disappeared at the evaluation stage in the clonal nursery under normal and restricted irrigated conditions. In general, all selection criteria, except selection based on HR Brix, gave similar responses for brix yield. Low repeatability of traits, insignificant regression coecients, and low proportion of clones outyielding the best standard variety CoH 35 at selection and evaluation stages indicated the ineffectiveness of selection at the single-stool ratoon seedlings stage. The reasons for ineffectiveness of selection based on the selection index are discussed.

Off-season Production of Primocane-fruiting Red Raspberry Using Summer Pruning and Polyethylene Tunnels

The spring shoots of `Autumn Bliss' red raspberry (Rubus idaeus L. var. idaeus; primocane-fruiting type) were cut on 2, 16, 31 July and 15 and 30 Aug. with the objective of delaying fruit harvest into the off-season under mild winter climatic conditions. Cutting shoots in August delayed fruit harvest until February and April of the following year, but shoot growth was weak and fruit yield low (4.8 and 2.1 g/cane). July cuttings delayed harvest until October to January with acceptable fruit yield (63.5, 52.8, and 26.5 g/cane for 2, 16, and 31 July, respectively). The differences in cane height and total node and fruiting node count between the three cutting dates of July were small, but there was a constant decrease in leaf area per cane from the first to the third date and a sharp decrease in fruit yield from the second to the third date. Vegetative shoot growth was less affected than yield when summer cutting was delayed until the end of July to induce a later harvest. Fruit quality always reached acceptable standards. This study confirms the practicability of using summer-cutting of primocane-fruiting red raspberries to induce off-season fruit production under protected cultivation in mild winter climates.